Güngör HC. Management of crown-related fractures in children: an update review. Dent Traumatol. 2014; 30:88-99
Bourguignon C, Cohenca N, Lauridsen E International Association of Dental Traumatology guidelines for the management of traumatic dental injuries: 1. Fractures and luxations. Dent Traumatol. 2020; 36:314-330
Love RM, Jenkinson HF. Invasion of dentinal tubules by oral bacteria. Crit Rev Oral Biol Med. 2002; 13:171-183
Díaz JA, Bustos L, Brandt AC, Fernández BE. Dental injuries among children and adolescents aged 1–15 years attending to public hospital in Temuco, Chile. Dent Traumatol. 2010; 26:254-261
Pashley DH. Dynamics of the pulpo-dentin complex. Crit Rev Oral Biol Med. 1996; 7:104-133
Moule A, Cohenca N. Emergency assessment and treatment planning for traumatic dental injuries. Aust Dent J. 2016; 61:21-38
Ram D, Fuks AB. Clinical performance of resin-bonded composite strip crowns in primary incisors: a retrospective study. Int J Paediatr Dent. 2006; 16:49-54
O'Reilly C, Tanday A. Technique tips. The modified transparent crown: different applications for the conventional cellulose acetate anterior crown former. Dent Update. 2019; 46:894-897
Denis M, Atlan A, Vennat E White defects on enamel: diagnosis and anatomopathology: two essential factors for proper treatment (part 1). Int Orthod. 2013; 11:139-165
Field R. Aesthetic management of white lesions in the permanent dentition. Dent Update. 2019; 46:313-322
Marshman Z, Rodd HD. The psychosocial impacts of developmental enamel defects in children and young people. In: In Drummond BK, Kilpatrick N (eds). Berlin: Springer; 2015
Almuallem Z, Busuttil-Naudi A. Molar incisor hypomineralisation (MIH) – an overview. Br Dent J. 2018; 225:601-609
Discepolo KE, Baker S. Adjuncts to traditional local anesthesia techniques in instance of hypomineralized teeth. N Y State Dent J. 2011; 77:22-27
Baroni C, Marchionni S. MIH supplementation strategies: prospective clinical and laboratory trial. J Dent Res. 2011; 90:371-376
Pasini M, Giuca MR, Scatena M Molar incisor hypomineralization treatment with casein phosphopeptide and amorphous calcium phosphate in children. Minerva Stomatol. 2018; 67:20-25
Shen P, Manton DJ, Cochrane NJ Effect of added calcium phosphate on enamel remineralization by fluoride in a randomized controlled in situ trial. J Dent. 2011; 39:518-525
Al-Batayneh OB, Jbarat RA, Al-Khateeb SN. Effect of application sequence of fluoride and CPP-ACP on remineralization of white spot lesions in primary teeth: an in-vitro study. Arch Oral Biol. 2017; 83:236-240
Abbasi Z, Bahrololoom M, Shariat M, Bagheri R. Bioactive glasses in dentistry: a review. J Dent Biomater. 2015; 2:1-9
da Silva-Junior GP, de Almeida Souza LM, Groppo FC. Comparison of articaine and lidocaine for buccal infiltration after inferior alveolar nerve block for intraoperative pain control during impacted mandibular third molar surgery. Anesth Prog. 2017; 64:80-84
William V, Messer LB, Burrow MF. Molar incisor hypomineralization: review and recommendations for clinical management. Pediatr Dent. 2006; 28:224-232
Barber A, King P. Management of the single discoloured tooth. Part 1: aetiology, prevention and minimally invasive restorative options. Dent Update. 2014; 41:98-108
Greenwall-Cohen J, Greenwall L, Haywood V, Harley K. Tooth whitening for the under-18-year-old patient. Br Dent J. 2018; 225:19-26
Pini NI, Sundfeld-Neto D, Aguiar FH Enamel microabrasion: an overview of clinical and scientific considerations. World J Clin Cases. 2015; 3:34-41
Donly KJ, O'Neill M, Croll TP. Enamel microabrasion: a microscopic evaluation of the ‘abrosion effect.’. Quintessence Int. 1992; 23:175-179
Ashfaq N, Grindrod M, Barry S. A discoloured anterior tooth: enamel microabrasion. Br Dent J. 2019; 226
Sundfeld RH, Croll TP, Briso AL Considerations about enamel microabrasion after 18 years. Am J Dent. 2007; 20:67-72
Sundfeld RH, Sundfeld-Neto D, Machado LS Microabrasion in tooth enamel discoloration defects: three cases with long-term follow-ups. J Appl Oral Sci. 2014; 22:347-354
Chawla R, Patel A, Dunkley S. Technique tips: microabrasion. Dent Update. 2018; 45:172-173
Bryan RA, Welbury RR. Treatment of aesthetic problems in paediatric dentistry. Dent Update. 2003; 30:307-313
Wright JT. The etch-bleach-seal technique for managing stained enamel defects in young permanent incisors. Pediatr Dent. 2002; 24:249-252
Venezie RD, Vadiakas G, Christensen JR, Wright JT. Enamel pretreatment with sodium hypochlorite to enhance bonding in hypocalcified amelogenesis imperfecta: case report and SEM analysis. Pediatr Dent. 1994; 16:433-436
Boersma JG, van der Veen MH, Lagerweij MD Caries prevalence measured with QLF after treatment with fixed orthodontic appliances: influencing factors. Caries Res. 2005; 39:41-47
Richter AE, Arruda AO, Peters MC, Sohn W. Incidence of caries lesions among patients treated with comprehensive orthodontics. Am J Orthod Dentofacial Orthop. 2011; 139:657-664
Attal JP, Atlan A, Denis M White spots on enamel: treatment protocol by superficial or deep infiltration (part 2). Int Orthod. 2014; 12:1-31
Paris S, Schwendicke F, Keltsch J Masking of white spot lesions by resin infiltration in vitro. J Dent. 2013; 41:e28-34
Smith MC, Lantz EM, Smith HV. The cause of mottled enamel. Science. 1931; 74
Tirlet G, Chabouis HF, Attal JP. Infiltration, a new therapy for masking enamel white spots: a 19-month follow-up case series. Eur J Esthet Dent. 2013; 8:180-190
Jälevik B. Prevalence and diagnosis of molar-incisor-hypomineralisation (mih): a systematic review. Eur Arch Paediatr Dent. 2010; 11:59-64
Jälevik B, Norén JG. Enamel hypomineralization of permanent first molars: a morphological study and survey of possible aetiological factors. Int J Paediatr Dent. 2000; 10:278-289
Farah R, Drummond B, Swain M, Williams S. Linking the clinical presentation of molar-incisor hypomineralisation to its mineral density. Int J Paediatr Dent. 2010; 20:353-360
William V, Burrow MF, Palamara JE, Messer LB. Microshear bond strength of resin composite to teeth affected by molar hypomineralization using 2 adhesive systems. Pediatr Dent. 2006; 28:233-241
Jälevik B, Klingberg GA. Dental treatment, dental fear and behaviour management problems in children with severe enamel hypomineralization of their permanent first molars. Int J Paediatr Dent. 2002; 12:24-32
Lagarde M, Vennat E, Attal JP, Dursun E. Strategies to optimize bonding of adhesive materials to molar-incisor hypomineralization-affected enamel: a systematic review. Int J Paediatr Dent. 2020; 30:405-420 https://doi.org/10.1111/ipd.12621
Crombie F, Manton D, Palamara J, Reynolds E. Resin infiltration of developmentally hypomineralised enamel. Int J Paediatr Dent. 2014; 24:51-55
Stachniss V, Frankenberger R. Bonding strategies for MIH-affected enamel and dentin. Dent Mater. 2018; 34:331-340
Chay PL, Manton DJ, Palamara JE. The effect of resin infiltration and oxidative pre-treatment on microshear bond strength of resin composite to hypomineralised enamel. Int J Paediatr Dent. 2014; 24:252-267
Wiegand A, Stawarczyk B, Kolakovic M Adhesive performance of a caries infiltrant on sound and demineralised enamel. J Dent. 2011; 39:117-121
Ekizer A, Zorba YO, Uysal T, Ayrikcila S. Effects of demineralizaton-inhibition procedures on the bond strength of brackets bonded to demineralized enamel surface. Korean J Orthod. 2012; 42:17-22
Knösel M, Eckstein A, Helms HJ. Durability of esthetic improvement following Icon resin infiltration of multibracket-induced white spot lesions compared with no therapy over 6 months: a single-center, split-mouth, randomized clinical trial. Am J Orthod Dentofacial Orthop. 2013; 144:86-96
Cohen-Carneiro F, Pascareli AM, Christino MR Color stability of carious incipient lesions located in enamel and treated with resin infiltration or remineralization. Int J Paediatr Dent. 2014; 24:277-285
Kim S, Kim EY, Jeong TS, Kim JW. The evaluation of resin infiltration for masking labial enamel white spot lesions. Int J Paediatr Dent. 2011; 21:241-248
Felippe LA, Monteiro S, Baratieri LN Using opaquers under direct composite resin veneers: an illustrated review of the technique. J Esthet Restor Dent. 2003; 15:327-336
Kelleher MG, Roe FJ. The safety-in-use of 10% carbamide peroxide (Opalescence) for bleaching teeth under the supervision of a dentist. Br Dent J. 1999; 187:190-194
Marin PD, Bartold PM, Heithersay GS. Tooth discoloration by blood: an in vitro histochemical study. Dent Traumatol. 1997; 13:132-138
Kaur M, Singh H, Dhillon JS MTA versus Biodentine: review of literature with a comparative analysis. J Clin Diagn Res. 2017; 11:Zg01-zg5
Vallés M, Mercadé M, Duran-Sindreu F Influence of light and oxygen on the color stability of five calcium silicate-based materials. J Endod. 2013; 39:525-528
Torabinejad M, Parirokh M, Dummer PMH. Mineral trioxide aggregate and other bioactive endodontic cements: an updated overview – part II: other clinical applications and complications. Int Endod J. 2018; 51:284-317
Akbari M, Rouhani A, Samiee S, Jafarzadeh H. Effect of dentin bonding agent on the prevention of tooth discoloration produced by mineral trioxide aggregate. Int J Dent. 2012; 2012 https://doi.org/10.1155/2012/563203
Gürel MA, Kivanç BH, Ekici A, Alaçam T. Evaluation of crown discoloration induced by endodontic sealers and colour change ratio determination after bleaching. Aust Endod J. 2016; 42:119-123 https://doi.org/10.1111/aej.12147
Advancements in material science have contributed greatly towards aesthetic dentistry. However, achieving satisfactory aesthetics for children in the developing dentition poses unique challenges. Challenges include, but are not limited to: (1) patient co-operation; (2) optimum moisture control; (3) continuing gingival maturation and bone growth; and (4) the increased need for minimally invasive and non-irreversible techniques to maintain future treatment options. This article addresses the common paediatric dental aesthetic challenges of uncomplicated crown fractures (ie those confined to enamel and dentine), localized, discrete enamel opacities and intrinsic discolouration of anterior, root canal-treated teeth. Treatment techniques and helpful tips for the general dental practitioner are presented.
CPD/Clinical Relevance: This article focuses on common dental aesthetic challenges that present in the paediatric dental population and suggests methods to manage this effectively in primary and secondary care.
Article
Managing dental trauma, especially in younger patients, can be challenging. Emergency treatment carries additional demands as patients and their parents/carers are likely to be distressed, with limited patient dental treatment experience and need to be accommodated for treatment into a busy clinical schedule. However, immediate and appropriate primary care management of dental trauma is critical for ensuring an optimal dental outcome. Epidemiological data from the 2013 Children Dental Health Survey reported an increased prevalence of enameldentine fractures in maxillary central incisors from 5.9 per thousand to 9.4 per thousand in 15-year-olds from 2003 to 2013.1 In both primary and permanent dentitions, maxillary central incisors are most frequently affected. Uncomplicated enamel-dentine fractures are the most common type of dental injury in the permanent dentition and prevalence in this group varies from 2.4% to 33%.2 Risk factors for dental trauma include increased overjet with proclined teeth, incompetent lips, mouth breathing, participation in high/medium trauma risk sports (eg mountain biking/basketball), and medical conditions such as attention deficit disorder, epilepsy and cerebral palsy.2 Clinicians should therefore advocate the use of mouth guards during contact sports and make an orthodontic referral at the appropriate stage in dental development.
Rationale for treatment of enamel–dentine fractures
Uncomplicated crown (enamel-dentine) fractures result in loss of enamel and dentine without exposure of the pulp.3 Dentine tubules become exposed and can act as a pathway for bacterial ingression towards the pulp, resulting in pulpal disease. In vivo studies have demonstrated the invasion of tubules by bacteria within 1 week of exposure.4 The dentine–pulp complex responds to reduce the diffusion of noxious stimuli by:
Increasing the outward flow of dentinal fluid by inflammatory processes;5
Reducing permeability of dentine through production of sclerotic or reparative dentine.6
This requires an intact blood supply to the pulp complex. Sealing of the dentinal tubules is essential to prevent bacterial invasion from overcoming the pulpo–dentinal defence mechanisms and resulting in infection of the pulp and root canals.4 The extent of the fracture is useful in assessing the prognosis of the pulp with deeply extending corner fractures resulting in poorer pulpal prognosis than superficial, horizontal ones.7
The International Association of Dental Traumatology (IADT) published new guidelines in 2020 that can be used to help establish a diagnosis of an uncomplicated, enamel-dentine crown fracture.3 This involves appropriate history-taking, pulp sensibility testing, radiographs and clinical photographs. If the patient presents with the tooth fragment, it is preferable to first attempt re-attachment of this fragment with composite resin or resin cement to achieve optimum aesthetics. If the fragment is not available, a composite resin restoration to seal the dentine should be provided. A cellulose acetate crown could be used to decrease clinical chair time and provide satisfactory aesthetics.
The cellulose acetate transparent crown former (also known as a strip crown) has been used in restoring traumatized and carious anterior teeth with composite for over 30 years. These crown forms have a reported success rate of 80% after at least 24 months in the primary dentition8 but they can also be used in the permanent dentition. Crown former kits have a large variety of sizes with many fitting more appropriately to that of permanent incisor crowns. These transparent crown formers are sold in multipack boxes (eg Strip-Off Crown Form Clear Anterior pack of 60, Henry Schein, UK) with pictorial guides, and are very useful for restoring crown fractures (Figure 1). They can also be used to restore carious anterior teeth and help to mask discolouration.
Figure 1. Pre-operative (a) labial and (b) palatal aspects of an uncomplicated enamel–dentine fracture in UR1. (c) Isolation with dry dam and strip crown placed on UR1. Post-operative (d) labial and (e) palatal aspects of aspects of a resin-composite restoration to restore UR1 using a Strip-Off Crown Form. an uncomplicated enamel–dentine fracture in UR1.
Clinical aspects of treatment for using cellulose acetate transparent crown formers for enamel–dentine fractures
Composite shade selection
Consider wiping teeth with gauze/polishing teeth prior to restoring. When assessing the composite shade, apply a button of composite to the tooth, without etching or bonding, and spot cure for 5 seconds. The composite button can be removed easily with a flat plastic prior to starting the restoration. In emergency visits, where time is limited, A2 composite on the VITA shade guide is normally a good match for most paediatric trauma cases. In any case, shade correction can be addressed at subsequent visits.
Crown selection and adjustment
When selecting the crown size, it is useful to compare the mesiodistal width of the crown form with the mesiodistal width of the tooth. However, if the tooth has been fractured and complete loss of incisal edge has occurred, the contralateral incisor can be used to gauge the mesiodistal width and the appropriate crown form selected. A hole should be pierced in the mesial or distal incisal angle with a sharp explorer. This will create a core vent for the escape of air bubbles that can become entrapped in the crown. Take care not to damage the proximal seam of the strip crown and ensure this is intact before placement. Ideally curved-ended scissors (eg Beebee Crown Scissors), are used to roughly trim the margins to match those of the fractured tooth. Remember to take into consideration the rise of the gingival margin in the interproximal zone.
Moisture control
Moisture control is of key importance for placement of composite restorations. Use of a dry dam in anterior aesthetic work for paediatric patients is useful as ear ties can be used to stretch the dam and hold it in place. This negates the need for using local anaesthetic, rubber dam clamps and rubber dam frames to isolate the tooth/teeth to be restored. The following isolation techniques can be used. The choice is dependent on the level of patient co-operation and amount of tooth structure remaining. In certain cases, it may be necessary to give local anaesthetic and place an anterior rubber dam clamp to isolate a tooth when there is minimal tooth structure remaining.
Conventional dam technique using a dry dam
Punch small holes to allow isolation of the tooth to be restored and a tooth on either side. This can be secured as with a conventional dam around the teeth by inversion and use of rubber stabilizing cord (Wedjets, Coltene/Whaledent Ltd, West Sussex, UK) or floss ligatures.9
Use of light-cured liquid dam (Rubber Dam Liquid, Cerkamed, Poland) can also be syringed at the margins of the dam where it meets the tooth to achieve a greater level of isolation for fracture lines close to the gingival margin.9
Split dam technique using a dry dam
Two large holes are punched out, 1–2 cm apart, and are joined by a scissors cut. The rubber dam is positioned and held in place using rubber Wedjets.9
Alternatively
Cotton wool roll isolation, dry guards, good suction or OptraGate (Ivoclar Vivadent, UK) can be used.
Tooth preparation and final crown adjustments
A 2-mm bevel should be placed on the enamel edge to increase surface area for bonding and to blend the transition from composite to enamel. Place the strip crown over the prepared tooth and refine the margins using curved-ended scissors to ensure it seats so that the incisal edge of the crown is level with the adjacent tooth. The margins should sit just below the edge of the fracture line. However, in severe fractures, consider complete coronal coverage with the crown form to improve composite retention. Conduct a primary assessment of the occlusion to avoid lengthy adjustments at the end. Ask the patient to close teeth gently together when the crown is in place to assess for any occlusal interference. Selectively etch the tooth with 37% phosphoric acid, ensuring you protect neighbouring teeth using celluloid strips or PTFE tape, and do not over etch.9 Apply primer and bond in accordance with the manufacturer's instructions and light cure. Fill the strip crown with the chosen shade of composite. For improved aesthetics, the strip crown could be lined with a thin layer of enamel shade composite and the centre of the crown filled with a dentine composite shade. Ensure the composite is well packed and there are no air blows.
Seating the crown
Seat with gentle pressure and allow excess to extrude from the strip crown. Use a sharp explorer to remove the excess and apply more pressure to ensure the crown is fully seated and no further excess composite extrudes on pressure. Light cure each aspect for 20 seconds (labially, mesially, palatally and distally). Remove the strip crown gently with a blunt-ended instrument, such as a flat plastic, by wedging it between the strip crown and tooth and gently moving around the tooth, applying gentle upwards pressure. Carry out finishing and polishing and check occlusion after rubber dam removal.
Localized enamel opacities
Enamel is a highly mineralized tissue with 96% mineral content, in the form of hydroxyapatite, and 4% organic fluids.10 Healthy enamel has a refractive index similar to hydroxyapatite (RI=1.62).10 There are, therefore, very few interferences because light passes through enamel without deviation from its trajectory before it is reflected at the enamel–dentine interface. The law of optics indicates that when there is a difference of refractive index between two phases, there will be deviation of the incident light ray.10 Hypomineralized enamel has a reduced mineral phase, replaced by organic fluids. As incident light passes through hypomineralized enamel, it encounters multiple interferences from the mineral and organic fluid components of enamel, which have different indices of refraction. Incident light is reflected at each interface creating enamel that is very luminous.10 These areas show as white lesions or enamel opacities on teeth. In summary, an enamel opacity is an altered translucency of enamel.
Enamel hypomineralization can appear as well demarcated or diffuse opacities that can be white, cream, yellow or brown in colour. These defects can be localized or generalized. The aetiology of enamel hypomineralization can be divided into pre-eruptive (developmental) or post-eruptive (environmental) (Table 1).11 This article focuses on common, localized opacities as a result of fluorosis, molar–incisor hypomineralization (MIH), chronological hypomineralization and pre-cavitated carious lesions affecting the anterior teeth of our paediatric patients.
Pre-eruptive
Post-eruptive
Fluorosis
Pre-cavitated carious lesion
Molar-incisor-hypomineralization
Traumatic hypomineralization
Prenatal illness
Premature birth
Generalized hypomineralization is usually a result of inherited and systemic factors. These more severe forms should be appropriately referred to secondary care centres and their management is beyond the scope of this article. Dental hypomineralization is a common condition with the 2013 Child UK Dental Health Survey reporting that 28% of 12-year-olds had an enamel opacity or hypoplasia affecting one or more permanent teeth.12 It is important to be aware of the management options for these opacities because research has shown that they can impact negatively on patient's wellbeing and self-esteem.13 It can also lead to tooth sensitivity, which can result in poor oral hygiene and an increased caries risk.14
Tooth sensitivity management
It has been suggested that desensitizing toothpastes could be used pre-operatively to reduce sensitivity prior to the treatment appointment.15 Casein phosphopeptide amorphous calcium phosphate (CPP-ACP) has been recommended to aid remineralization early after eruption when enamel has not fully matured.16 The casein phosphate stabilizes the calcium phosphate and improves the bioavailability of calcium and phosphate in saliva. This has been shown to significantly improve sensitivity in MIH-affected teeth after 4 months.17 Tooth Mousse (GC Corporation, Tokyo, Japan) and MI Paste Plus (GC Corporation, Tokyo, Japan) are common dental products containing CPP-ACP. Research has shown that a combination of CPP-ACP and fluoride enhances remineralization.18,19 Enamelon Treatment Gel (Premier Dental, USA) is available and contains both fluoride (970ppm F) and ACP. Novamin (NovaMin Technology, GlaxoSmithKline, UK) is a toothpaste with an active bioglass particulate repair agent that mineralizes dentine porosities and reduces sensitivity.20 This can be used in Essix retainers overnight. Sensitivity can be managed during treatment by use of a rubber dam and high volume suction to protect other sensitive teeth during treatment.14 Local infiltration with articaine 4% local anaesthetic,21 the use of intraligamental, intra-osseous and palatal anaesthesia as an adjunct to standard local anaesthesia techniques15 and the use of inhalation sedation for additional pain management22 could also be considered.
Brown/yellow opacities
The aetiology of these lesions can be attributed to extrinsic and intrinsic discolouration (Table 2).23 Extrinsic discolouration is usually caused by generalized, superficial staining of teeth and is usually removed with scaling and polishing procedures. Intrinsic discolouration includes discolouration as a result of disturbances in the formation of dental tissues and those from post-eruptive alterations to tooth tissue. The timing of the impact caused by drug-related and metabolic factors in relation to tooth development will determine how many teeth, and to what extent they are affected, eg dental fluorosis. This can mean that only a few teeth are affected, and the condition is localized.23
Localized enamel hypoplasia as a result of trauma, infection or environmental factors
Chlorhexidine mouthwash
Treatment
Superficial enamel hypomineralization and intrinsic yellow/brown staining is amenable to tooth whitening with 10% carbamide peroxide to brighten the surrounding enamel.
Clinical technique for tooth whitening in paediatric patients24,25
Pre-operative photos, shade and sensibility testing for baseline records.
Take an alginate impression of the arch that requires whitening.
Construct a vacuum-formed, custom-made, non-reservoir, close fitting tray made from 0.35 mm soft acrylic. Non-scalloped tray design tends to be more comfortable and offers a better seal. 10% carbamide peroxide was designed as an oral antiseptic and therefore, soft tissue contact should have no negative consequence.
Provide the patient with instructions for use and advise daily use for a minimum of 2 hours under parental supervision. 10% carbamide peroxide can remain active for up to 10 hours and overnight wear is recommended for maximum benefit.
Advise the patient to avoid foods/drinks that may discolour the teeth during whitening. If sensitivity is experienced, consider reducing carbamide peroxide whitening time or using potassium nitrate desensitizing agents in a custom tray. A desensitizing toothpaste for brushing could also be recommended.
Review after 2 weeks
The conservative nature of this technique does not preclude further management with microabrasion or resin infiltration with Icon (DMG Hamburg, Germany). However, tooth whitening has restrictions for its use in under 18s.
In October 2012, the European Union changed the law regarding tooth whitening. The regulation stipulates that products containing or releasing up to 6% hydrogen peroxide can be used under the following conditions:
To be done only by dental practitioners or under their direct supervision’;
Products are ‘not to be used on a person under 18 years of age.’26
The General Dental Council (GDC) released a position statement on tooth whitening stating that ‘products containing or releasing between 0.1% and 6% hydrogen peroxide cannot be used on any person under 18 years of age except where such use is intended wholly for the purpose of treating or preventing disease.’27 The GDC did not stipulate the clinical indications for which tooth whitening would be considered to be treating or preventing disease. However, a list of conditions has been proposed by Greenwall25 (Table 3). Many have advocated seeking advice from indemnity providers prior to undertaking paediatric tooth whitening treatments. This resulted in Dental Protection releasing a statement in March 2019, ‘Any decision to break the law in order to provide tooth whitening is a matter for the judgement of the clinician, but it is crucial to keep in mind that a breach of the regulations will constitute a criminal offence, irrespective of the intention behind this.’ They concluded with, ‘Dental Protection can support members in relation to the expectations of the GDC or with advice on any other aspects of this topic (tooth whitening in under 18s).’28 Legislation is not black and is certainly not white. Ironically, whitening regulations have put clinicians in a rather grey, ethical decision-making dilemma. Done with appropriate informed consent and record collection, the clinician can act in a paediatric patient's best interest, thereby enabling tooth whitening to be a treatment option in cases of tooth discolouration whereby the patient's quality of life or self-esteem are affected.
Enamel conditions
Severe and moderate discolouration
White opacities
Brown, orange and yellow staining
Coronal defects (discrepancies in tooth shape, size, position, proportion, shade and number)
Systemic disease with dental effect (liver, kidney and haemorrhagic diseases)
Microabrasion
Microabrasion is a useful technique to blend very superficial developmental mineralization defects limited to the enamel layer and internalized superficial stains. Microabrasion uses an acid and an abrasive compound to remove only a superficial enamel layer, and is considered a minimally invasive and safe technique.29 This creates a dense prism-free surface that alters the optimal properties of enamel and is described as the ‘abrosion effect’.30 It may also aid in minimizing the challenges of masking the defect later with a direct/indirect composite restoration or a ceramic veneer if required, following completion of skeletal growth.
Stains or defects restricted to superficial enamel;
Mild–moderate dental fluorosis;
Correction of surface irregularities;
Localized enamel hypoplasia limited to the outer layer of enamel (may require resin infiltration ± restorative approach for deeper areas of hypoplasia);
Removal of residual composite after orthodontic debond.
Microabrasion should not be used in those with sensitive teeth, poor co-operation or in those with deep hypoplastic lesions of enamel, such as amelogenesis imperfecta or in cases of dentinogenesis imperfecta.31 The main consideration for enamel microabrasion is the depth and location of the hypomineralization and/or staining.32 The depth can be estimated by transillumination using an LED source on the labial or palatal surface.33 The more light blocked by the enamel opacities/staining, the darker the colour of this area and the deeper the hypomineralization/staining is. This diagnosis should be made in wet conditions as there is a greater difference in refractive index between air and enamel than water and enamel. Microabrasion should be used cautiously in those with a defective lip seal as the anterior teeth will dehydrate more easily and this will accentuate the opacity.30
This technique has several advantages. It is safe, conservative, leaves enamel surfaces lustrous, reduces bacterial colonization of the enamel surface and has lasting, stable aesthetic results.30,33
Pre-operative photos and sensibility testing should be taken prior to treatment.
The teeth requiring microabrasion should be isolated using a rubber dam to protect the gingiva.
A slurry is made in a dappen pot using an equal mix of 37% phosphoric acid and pumice and is applied to the teeth using a rubber cup in a slow speed handpiece at 1000ppm for 30–40 seconds. (Alternatively, a wooden stick can be used to rub on the slurry for 1–2 minutes to reduce acid splatter.)
Rinse off the slurry and repeat the application up to three times, if required.
Apply fluoride after microabrasion: 0.2% sodium fluoride liquid or 2800ppm sodium fluoride toothpaste. Toothpaste should be white and not coloured.
Advise patient not to consume coloured food/drink for at least 48 hours following their treatment.
Arrange for a 1-month post-treatment review with photographs.
Figure 2.
(a) Localized, diffuse brown labial opacity along incisal third UR1 likely to have been caused by trauma to URA. (b) After completion of microabrasion to UR1 with 37% phosphoric acid and pumice slurry.
Alternatively, 6.6% hydrochloric acid with silicon carbide particles (eg Opalustre, Ultradent, UK) may be used up to 10 times for 60 seconds.29,34 Another option is to apply an equal mix of 18% hydrochloric acid and pumice using a rubber cup or wooden spatula for 5 seconds, up to a maximum of 10 times. For this latter technique, it is recommended to apply Vaseline to the gingiva and a mixture of sodium bicarbonate and water on the rubber dam behind the teeth in case of spillage.35
Etch-bleach-seal technique
Another treatment for localized enamel hypomineralization with yellow-brown intrinsic staining is the ‘etch-bleach-seal technique.’36 It has been suggested that the sodium hypochlorite used to bleach the teeth removes enamel proteins, allowing for improved etching of the enamel surface and a better chance of successful bonding of resin.37 In light of current guidance around tooth whitening for the under 18s, this could be a useful tool for general dental practitioners in co-operative patients.
Clinical technique for ‘etch-bleach-seal technique36
Moisture control with rubber dam
The tooth is etched with 37% phosphoric acid for 60 seconds.
Bleach, 5% sodium hypochlorite, is continuously applied to the tooth for 10–15 minutes using a cotton applicator. If there is no change after 10 minutes, re-etch for 60 seconds, rinse and continuously reapply sodium hypochlorite for up to 20 minutes in one appointment. The tooth may need further whitening at another appointment.
The tooth is then re-etched for 30 seconds with 37% phosphoric acid, washed and sealed using a clear resin sealant.
This technique for whitening could be used in combination with Icon resin infiltration instead of a clear resin sealant.10
White opacities
Histologically, white enamel opacities have a reduced total mineral content and are less organized when compared to unaffected enamel.10 Saliva, which is supersaturated with calcium and phosphate ions, can form a superficial mineralized enamel surface layer. Light rays entering these opacities deviate from their trajectory multiple times due to the differing refractive indices within the lesion. The reflected light therefore appears much brighter than the surrounding healthy enamel.10
Minimally invasive treatment of localized white opacities includes resin infiltration using Icon. Resin infiltration aims to remove this superficial mineralized layer, permitting a low viscosity resin with a similar refractive index to healthy enamel to infiltrate the hypomineralized opacity and mimic the translucent properties of healthy enamel.11 However, there has been a varied level of success with this technique. A new approach divides treatment into superficial and deep infiltrations, the choice of technique dependent on the depth and origin of hypomineralization.11
There is a high prevalence of white spot lesions after fixed-appliance therapy.38,39 A study by Boersma et al that used quantitative light-induced fluoresence found that 97% of patients had white spot lesions immediately after debond of fixed appliances.38 These lesions are most commonly diagnosed clinically using the International Caries Detection and Assessment System (ICDAS). On smooth surfaces, these lesions are normally found on surfaces where plaque stagnates, for example the labial cervical surface or around orthodontic brackets. They are opaque, chalky, white opacities that have a rougher surface texture.10 Histologically, the caries process causes mineral dissolution along weak points in enamel, the striae of Retzius and along the prisms longitudinally. This causes enlargement of the enamel pores while preserving the enamel scaffold.10 The body of this lesion progresses in a half moon shape to the demineralization front. The surface layer of the lesion remains intact due to the dynamic process of demineralization and remineralization by supersaturated saliva.10
Treatment of white spot lesions
Carious lesions scoring an ICDAS 0 or 1 have only slight subsurface enamel hypomineralization (limited to external half of enamel in most cases). Remineralization of these opacities may be obtained by fluoride or casein phosphopeptide treatment (CPP-ACP Tooth Mousse).
Lesions scoring ICDAS 2, have a greater depth of subsurface demineralization without surface cavitation. Remineralization treatments may not guarantee full depth re-precipitation of lost minerals, resulting in a residual white opacity that may stain because of the inclusion of external pigments over time. The treatment of choice is resin infiltration with Icon.10
Clinical technique for resin infiltration using Icon40
Apply Icon-Etch (HCL gel)
Apply Icon-Etch to extend at least 2 mm around the white opacities and agitate with an instrument because it will buffer shortly after tooth surface contact. After 2 minutes the etching gel is removed with water for 30 seconds and the surface is dried.
Apply Icon-Dry (ethanol)
When Icon-Dry is applied, the opacities should disappear for the wetting moment. This gives the operator a preview of the results. If the whitish opacities on the etched enamel diminish, Icon-Infiltrant can be applied. If the white opacities are still visible with Icon-Dry, the etching step should be repeated up to a maximum of five times. If aesthetics are acceptable, after 30 seconds with Icon-Dry on the surface to desiccate enamel, thoroughly dry with oil-free and water-free air.
Apply Icon-Infiltrant (unfilled resin)
Continuous feeding of infiltrant to surface for 3 minutes. Excess material is removed before it is light cured for 40 seconds. This step is repeated, letting the infiltrant set again for 1 minute before excess removal and light curing for 40 seconds. Attal et al recommend applying a layer of glycerine to limit the layer inhibited by oxygen and a final light cure.41 Finally the surfaces are polished to improve colour stability.42
Pre-eruptive damage
Fluorosis
Chronological hypomineralization
MIH
Fluorosis
Fluorosis is hypomineralization of the enamel as a result of excess fluoride being incorporated during its formation.43 It is caused by systemic absorption of fluoride during dental development. There is, therefore, a delayed diagnosis as teeth must be assessed clinically. Fluorosis is characterized by symmetrical involvement of homologous teeth. The extent of fluorosis and the teeth involved can help to estimate the time of excessive fluoride ingestion. Clinically, there are thin, horizontal, white lines, which may be accompanied by irregular chalky zones creating a parchment-type appearance.10 Discolouration can occur due to infiltration of exogenous pigments. In more severe cases, there are alterations to the fluorotic enamel from physical and chemical substances in the mouth resulting in pits and fissures.10 Fluorosis classifications include Dean's Index and Horowitz's Tooth Surface Index of Fluorosis (TSIF). The TSIF classification includes extent of enamel involvement and the clinical picture (Table 4). Histologically, fluorosis (TSIF ≤4) have a hypermineralized surface layer without pitting, and a hypomineralized subsurface layer similar to white spot lesions, which usually extends less than one-third into enamel.10
Stage
Clinical criteria
0
No sign of fluorosis
1
Fluorosis is limited to the cusp tips with a snowy-white occlusal cap on the molars
2
White parchment-like appearance on less than two-thirds of the enamel surface
3
White parchment-like appearance on at least two-thirds of the enamel surface
4
Discoloured areas with patches ranging from very pale to dark brown
5
Slight stippling with discolouring of pits
6
Slight stippling with change of enamel colour
7
Pits merge forming wide areas of dark brown enamel alongside areas where the enamel is no longer present
Treatment
Although fluorotic enamel is more caries resistant than normal enamel, there is a psychological impact that cannot be ignored. Tooth whitening with 10% carbamide peroxide to brighten the enamel surrounding the fluorotic opacities can be considered. However, this is not always sufficient.
Owing to the histological similarities between fluorosis and white spot lesions, resin infiltration can be effective at masking fluorotic opacities. The urea in the carbamide peroxide deproteinizes the fluorotic enamel, improving the penetration of resin. Aesthetic results have been reported for fluorosis by combining these two techniques with 19-month follow-up.44 Ideally tooth whitening should be performed prior to resin infiltration because it is not permeable to carbamide peroxide. Again, teeth whitening treatment in under 18s remains a contentious issue.
Chronological hypomineralization of a permanent tooth results from periodontal trauma or peri-apical infections affecting primary teeth. Age at the time of the trauma can present with varying sequelae. Trauma and consequent disturbance during the maturation phase of amelogenesis results in hypomineralization, and trauma during the secretion phase can lead to hypoplasia.10 Clinical presentation of the hypomineralizations can vary. Generally, they are well-defined white lesions affecting the incisal third of crowns. They can exhibit brown discolouration when haemorrhage has occurred into the hypomineralized area.11 They are asymmetrical insofar as they can affect the opposing teeth and not usually contralateral teeth. Histologically, they are similar to white spot lesions and fluorosis in that they have a subsurface layer of hypomineralization with a superficial layer of mineralized enamel. However, there is great variation in the depth of this hypomineralized layer and in the angle formed with the enamel surface layer.10
Figure 3.
(a) Chronological hypomineralization visible as diffuse white opacity LL1. (b) Mock-up labial composite veneer camouflage LL1. Patient decided against this. (c) Resin infiltration with Icon (DMG Hamburg, Germany). LL1 white opacity has been blended into surrounding enamel.
Treatment
If the subsurface hypomineralized layer is circular in shape and forms an acute angle with the enamel surface, it is difficult for the resin infiltration to completely penetrate the margins of the lesion. This may lead to incomplete infiltration peripherally, resulting in the ‘edge effect’ or ‘white halo’, which can sometimes look worse than the initial opacity. It has been suggested that increased peripheral erosion with hydrochloric acid with or without sandblasting prior to resin infiltration, may help to overcome this issue, although further research is required.10
In cases similar to white spot lesions and fluorosis, where the subsurface hypomineralized layer produces an acute angle with the enamel surface, the resin can penetrate the margins to achieve complete resolution of the opacity.
Molar-incisor hypomineralization (MIH)
MIH has been defined as a hypomineralization of systemic origin of one to four permanent first molars (FPM) frequently associated with affected incisors.45 It has a worldwide prevalence of between 2.4% and 40.2%.46 Aetiology is multi-factorial and may include premature births, low birth weight, respiratory diseases, and prolonged breast feeding or systemic conditions from birth to 3 years of age.47 MIH is diagnosed clinically by well-defined white/yellow/brown opacities usually affecting the occlusal/incisal third of crowns of FPMs/incisors, the cervical third is rarely involved. These opacities may be irregular and appear asymmetrically on homologous teeth. In contrast to teeth affected by fluorosis, teeth with MIH are more prone to caries. MIH more severely affects FPMs that have high occlusal loading, and can result in post-eruptive breakdown leading to sensitivity and increased caries risk.45 Incisors tend to be more mildly affected and have reduced occlusal loads, with a depth of healthy surface enamel that remains intact. A study by Farah et al48 linked the clinical appearance of MIH opacities to the mineral density within the lesion. The Chawla MIH classification correlated with Farah's mineral density data to link the shade of the opacity to the degree of demineralization in order to classify the lesion as ‘slight’ or ‘severe’ (Table 5). White opacities have a mild demineralization and therefore an MIH severity score of ‘slight’. Histologically, the hypomineralization begins at the dentino-enamel junction and not at the enamel surface.10 ‘Slight’ cases of white opacities have hypomineralization limited to the inner third of enamel. Severe cases can affect the entire layer of enamel.10
Severity of MIH
Shade of enamel
Mineral density of enamel correlating to the degree of hypomineralization
Slight
Creamy-white enamel opacity
2.22 g/m3
Severe
Brown-yellow opacity of enamel
<1.95 g/m3
Treatment
The issue lies in accessing the area of hypomineralization that lies beneath a deeper layer of healthy enamel than in cases of white spots and fluorosis. Resin infiltration alone would require excessive pre-erosion treatment with hydrochloric acid to expose the hypomineralized inner layer. The option is then to remove all or part of the lesion. Removing the entire lesion is destructive and risks dentine exposure. If removing only the healthy overlying enamel to access the ceiling of the lesion, will the adhesive bond to the hypomineralized enamel be satisfactory? Studies have shown it is difficult to achieve direct adhesion to hypomineralized enamel.49 In light of these challenges, a new protocol for deep infiltration has been developed.41
What cases are suitable for the deep infiltration technique?
This technique is designed for cases where the hypomineralization originates from the enamel–dentine layer, as in MIH, or for opacities with deeper hypomineralization arising from the surface (eg severe fluorosis, some cases of chronological hypomineralization). The use of a blue light-curing unit labially/palatally can help to assess the depth of the hypomineralization. It has been suggested that for areas where the blue light shines through as dark blue/black, the hypomineralization is considered deep and the deep infiltration approach should be used.50
What is the deep infiltration technique?
In order to either reach the ceiling of the subsurface hypomineralization originating at the enamel–dentine junction as in cases of MIH, or to allow for total penetration of the resin infiltration in deeper subsurface hypomineralization (eg chronological hypomineralization), surface enamel should be carefully removed. This can be achieved by sandblasting, use of soft flex discs or a diamond bur.10 The Icon system can then be applied to the tooth as previously described.
How do you know when you have removed enough enamel to reach the ceiling of hypomineralized enamel or to allow complete penetration of the deep hypomineralized enamel layer?
The Icon-Dry liquid is ethanol, which has a high refractive index, close to that of enamel. If, when the Icon-Dry is applied, the opacity is masked, then sufficient enamel has been removed to progress to the resin infiltration stage with a good aesthetic outcome. If the opacity is not sufficiently masked when Icon-Dry is applied, then further enamel removal or additional cycles of hydrochloric acid (Icon-Etch) should be considered.
What if there is a defect remaining in the surface enamel?
Application of an adhesive and a thin layer of enamel shade composite can be used to fill in any residual surface voids.41
Can you bond to hypomineralized enamel?
It is well documented that hypomineralized enamel is notoriously challenging to bond to. It has been reported that children with MIH need almost 10 times more dental treatment and often need re-treatment when compared to those who are unaffected.51 A systematic review identified three laboratory studies that addressed resin infiltration with Icon as a strategy to optimize bonding in MIH.52 Crombie et al found that Icon infiltration into MIH-affected enamel was erratic and unpredictable. This study did not use the deep infiltration technique, and there were two reported cases where no infiltration occurred as hypomineralization affected the inner half of enamel.53 Kramer et al also found there to be poor penetration of Icon and reported that pre-treatment with 5.25% NaOCl for 1 minute for enamel deproteinization after etching and before Icon-infiltration did not make a significant difference to bond strength and failure pattern.54 Contrary to this, Chay et al found that this same pre-treatment with 5.25% NaOCl improved the bond strength of composite to hypomineralized enamel regardless of whether Icon was used.55 The bonding between the resin infiltrant and composite has been found to be of good quality.56,57
How durable are results from resin infiltration?
Aesthetic results using Icon have been found to be stable up to 6 months.58 Others report that colour stability over time is the main issue with the Icon technique.59 A study by Paris et al concluded that polished infiltrated lesions are resistant to staining in vitro.42 Some authors have discovered that the aesthetic results of resin infiltration improve over time; however, the review was made at just 1 week and longer-term follow-up is required.60 Attal et al found improvement with time with resin infiltration. They proposed that the resin may absorb the residual water that was not removed by the ethanol and this may reduce the interference of light rays. When the deep infiltration technique by Attal et al is used, the placement of a surface composite layer means that the infiltrant is protected from the oral environment and is less likely to destabilize.10
Residual brown/yellow/white opacities
Vital tooth whitening, microabrasion and resin infiltration should be considered initially as these will blend or lighten the discolouration, making masking the discolouration easier to achieve with a thin, composite veneer. If the minimally invasive techniques for enamel discolouration already described have not been completely successful and/or enamel hypoplasia exists, composite restorations may be considered.
This technique can be carried out with little or no preparation to the tooth with optimum pain control and isolation techniques, making it an acceptable treatment for children. For severe discolourations, placement of an opaque composite layer over the discoloured areas of tooth may be required.61 It can be useful to adapt a strip crown into a labial veneer, ensuring enough mesial and distal coverage for aesthetics. A thin amount of enamel shade composite can be applied to the labial surface of the veneer, ensuring no voids. The veneer can be placed on the tooth and excess removed with a probe before curing. This produces a glossy finish requiring minimal finishing and polishing (Figure 4). Alternatively, direct composite veneers can be achieved free hand, but will require more polishing (Figure 5). The disadvantage of composite veneers is that they will require maintenance, limit the option of tooth whitening treatments and minimize further bonding potential in the future.
Figure 4.
(a) UR1 with diffuse, light brown opacity and hypoplasia. (b) UR1 after composite placement using the strip crown veneer matrix technique. The white opacities still remain, but the patient was delighted with the aesthetic outcome as UR1 and UL1 are now more alike.Figure 5.
(a) UR1 with light brown labial opacity and hypoplasia. Patient opted for composite restoration. (b) UR1 after free-hand composite restoration.
Tooth discolouration after root canal treatment
Aetiology
Tooth discolouration can impact on a person's self-image, confidence and physical attractiveness.62 The cause of discolouration after root canal treatment is most commonly due to breakdown products of haemoglobin or other haematin molecules from the dental pulp, often following trauma.63 Iatrogenic causes of discolouration include dental materials such as gutta percha or cements in the coronal part of the access cavity, and coronal pulpal remnants left in access cavity (Table 6).24 With the availability of magnification for root canal treatments and wide availability of long shank/gooseneck burs or heated instruments for removal of coronal gutta percha, iatrogenic causes of staining should be avoided.
Blood breakdown products in dentinal tubules
Pulp remnants in access cavity
Root canal cement or gutta percha in coronal portion of access cavity
Red-brown precipitate formed by irrigating with sodium hypochlorite and chlorhexidine
The clinical uses of mineral trioxide aggregate (MTA) and other bioactive cements include, but are not limited to, pulp capping, pulpotomy, perforation repair and apical plugs during apexification. The drawbacks of MTA include its relatively long setting time, difficult handling, high cost and discolouration potential.64 Valles et al showed that Biodentine was more colour stable than ProRoot White MTA, Portland cement with bismuth oxide and Angelus White MTA under a combination of light and anaerobic conditions, similar to the clinical setting.65
Discolouration using MTA (ProRoot, tooth-coloured ProRoot, Angelus, white Angelus) may result from blood contamination during placement, interaction of bismuth oxide with sodium hypochlorite irrigation or placement of MTA in a light, oxygen-free environment.66 To avoid MTA-related discolouration, placement of a double layer of dentine bonding agent in the access cavity prior to cement placement in the root canal67 or careful avoidance of blood contamination during MTA placement has been recommended. Alternatively, Biodentine could be considered because it has been shown to discolour less than MTA. Tooth discolouration resulting from bioactive endodontic cements is amenable to treatment by internal tooth whitening.68
The conservative treatment of choice in children for non-vital discoloured anterior teeth is the inside/outside open bleaching technique with 10% carbamide peroxide.
Figure 6.
(a) Lingual view of non-vital, discoloured root-treated LR1. History of root canal treatment completed 7 years previously in the Manchester Dental Hospital. No clinical signs or symptoms of root-canal treatment failure. Patient has had orthodontic treatment after root canal treatment was completed and now wears Essix retainers. (b) Peri-apical radiograph of LR1 root canal treatment, which was completed to a good standard. There are no obvious voids, the root-canal filling is well compacted but gutta-percha appears to extend slightly beyond the radiographic apex. A radiographic report advised that periodontal ligament widening may be a result of orthodontic movement and there is no radiographic evidence of root canal treatment failure for LR1. (c) Labial view of discoloured LR1. (d) Labial view of LR1 after inside/outside open bleaching. (e) Lingual view of LR1 8 weeks after internal–external bleaching with 10% carbamide peroxide and new composite restoration has been placed in the access cavity.
Pre-operative assessment
It is important to have a diagnosis and have carried out pre-treatment checks including:
Assessing the peri-apical status of the teeth and the quality of the root canal filling with respect to apical, lateral and coronal seal. If the root canal obturation is inadequate, this may require improving or replacing before commencing tooth whitening.
Providing the patient and their carers with all treatment options, risks and benefits.
Ensuring the patient is not allergic to plastic or peroxide. If inside/outside open bleaching is chosen as a whitening option, assess the shade and take a pre-operative clinical image with the shade tab beside the tooth as a baseline record.
Gaining informed consent following explanation and understanding of the risks and benefits of undertaking the treatment.
Take an alginate impression for construction of a whitening tray – a vacuum-formed, custom-made, non-reservoir, close-fitting tray made from 0.35-mm soft acrylic. Consider fabrication of a single tooth whitening tray with windows cut for the teeth on each side to avoid whitening of neighbouring teeth.
Check the fit and gingival extension of whitening tray and ensure the patient can insert and remove it independently.
Remove the access cavity restoration, ensuring total removal from the pulp chamber, and consider cleaning the cavity with an ultrasonic scaler.
Remove 2–3 mm of gutta percha to the enamel–dentine junction using heated pluggers or careful use of Gates Glidden burs.
Place a protective barrier over the gutta-percha (eg glass ionomer cement).
First whitening treatment performed in dental chair69
Insert tip of syringe into access cavity and load with 10% carbamide peroxide.
Place a pea-sized amount of 10% carbamide peroxide on the labial surface of the tooth to be bleached.
Insert the tray over the teeth and remove excess whitening gel from surrounding tissues using a tissue or soft toothbrush.
The first whitening treatment should be completed by a dental practitioner or under direct supervision.27
Patient instructions
Whitening gel can be changed every 2 hours during the day and can be worn overnight. The more often the bleach is changed, the more rapidly whitening will occur. There is no limit to the number of applications.
After whitening, clean the access cavity with a single-tufted brush.
Whitening trays can be cleaned with a soft brush with soapy, room temperature water and stored in a tray holder.
Review
Patient should be reviewed every 2–3 days and advised to cease whitening when they are happy with the shade.
After whitening, the access cavity should be cleaned with an ultrasonic scaler and access cavity sealed with a temporary restoration.
Definitive restoration
Delay definitive composite restoration until 2 weeks after the whitening to ensure no residual oxygen is left in the enamel, which would cause air inhibition of the composite bond.
Mechanism of action of 10% carbamide peroxide
Carbamide peroxide consists of equal amounts of hydrogen peroxide and urea. Carbamide peroxide releases (ie is equivalent to) approximately 3.5% hydrogen peroxide and a 3:1 relationship in terms of tooth whitening strength. The hydrogen peroxide breaks down into active free radicals that enter the dentinal tubules and decompose the molecules responsible for staining, thereby lightening the discolouration.
This technique seals 10% carbamide peroxide into the access cavity using a temporary restorative material. The patient carries out single tooth whitening externally.
Benefits of open and closed inside/outside bleaching techniques
The inside/outside open bleaching technique allows for a greater surface area to be whitened.69 However, 10% carbamide peroxide penetrates quickly through from the external surface.74
The inside/outside open bleaching technique does not require a temporary access cavity restoration, which could be lost or leak and allows for more frequent replacement of the 10% carbamide peroxide, which becomes inactive after 10 hours.
The inside/outside closed bleaching technique does not rely on the same level of patient co-operation as the open technique. If a patient does not keep the access cavity clean or does not return for a definitive restoration, they could jeopardize the success of the root canal treatment.24
Risks of internal bleaching techniques
Both techniques require good patient compliance and this should be explained to the patient and parent/guardian as part of informed consent. The patient must understand that, in the open technique, they need to return for closure of the access cavity to prevent bacterial ingress into the root canal. In both techniques, it is important to stress that neighbouring composite restorations will not bleach with the tooth and these may require replacement after the desired tooth shade from tooth whitening is achieved. Internal bleaching carries the risk of invasive cervical root resorption. This has been defined as a type of external root resorption characterized by invasion of root dentine by fibrovascular tissue derived from the periodontal ligament.70 Heithersay investigated 257 teeth for the causative factors of invasive cervical resorption. He concluded that trauma, orthodontics, intra-coronal tooth whitening, and surgery were strongly associated.71 The literature states that the use of 30% hydrogen peroxide, application of heat and a lack of a cervical barrier prior to commencing tooth whitening are risk factors for invasive cervical resorption following intra-coronal bleaching.72,73 10% carbamide peroxide releases only 3.5% hydrogen peroxide and the authors could find no cases of invasive cervical resorption reported from its use in the literature. Tooth whitening can cause gingival irritation. However, 10% carbamide peroxide's original purpose was as an oral antiseptic and therefore, gingival contact is not a concern. The urea present has beneficial cariostatic and antibacterial effects that improve gingival scores in patients who are likely to have poor gingival health from lack of motivation due to sensitivity.24
Restorative options
Tooth whitening could be considered a first-line option because it is conservative of tooth structure and will, at the very least, lighten the base tooth colour, making masking discolouration with restorative materials easier. If the patient is under 18 and the discolouration is still of concern, composite veneers using the strip crown technique described earlier could be considered as an interim solution until the patient's gingival tissues have matured and skeletal growth is complete At that stage, a porcelain veneer may be considered as a definitive restoration, bearing in mind that it could be destructive of hard dental tissue.
Discussion
This article has highlighted aesthetic dental challenges that can present in the paediatric population. Enamel–dentine fractures are common, and the dentine should be covered in general practice as soon as possible to preserve pulp vitality. A definitive composite restoration is within the remit of a general dental practitioner and often does not require local anaesthesia to complete. The benefit of having strip crowns in the dental practice is that they could save clinical time in these cases by minimizing shaping, polishing and finishing of composite. They can also be used as a clear veneer matrix in cases of labial opacities and discoloured root-treated teeth that have not responded to other conservative treatments. The materials for microabrasion, pumice and 37% phosphoric acid, are already widely available in general practices. This treatment is simple, not time consuming and can be very effective at managing cases of yellow/brown labial opacities. Finally, vital tooth whitening and open or closed inside/outside bleaching techniques with 10% carbamide peroxide are considered safe and minimally invasive treatments for discoloured teeth. They do, however, require excellent patient co-operation.
However, European law states that dental tooth whitening for patients under the age of 18 years is not permitted. The GDC have advised that tooth whitening could be used in treating dental disease, but there has been little clarification on this. Many clinicians would agree that tooth whitening is in the best interest of the patient. At this time, a referral for a specialist opinion could be sought because some secondary care centres do provide tooth whitening treatments to patients under the age of 18 years. It will be interesting to see what impact Brexit will have on the current tooth whitening regulations for under 18s.
Conclusion
The ability to treat paediatric patients effectively in primary care is a great practice builder. General practitioners have the skills and materials already available to manage aesthetic challenges such as these. Referring paediatric patients to dental hospitals for management of common aesthetic problems delays treatment and in cases of tooth discolouration, these children may be experiencing psychological difficulties. The current legislation on tooth whitening in under 18-year-olds poses a barrier to treatment. 10% carbamide peroxide is supported in the literature for its safety and efficacy in managing discolouration but unfortunately evidence-based dentistry is not supported by the law.
