Switch to Dark theme

References

Chate RAC. Truth or consequences: the potential implications of short-term cosmetic orthodontics for general dental practitioners. Br Dent J. 2013; 215:(11)551-553
Littlewood SJ, Millett DT, Doubleday B, Bearn DR, Worthington HV. Retention procedures for stabilising tooth position after treatment with orthodontic braces. Cochrane Database Systematic Reviews. 2006; 25:(1)
Prasad V, Ioannidis JP. Evidence-based de-implementation for contradicted, unproven, and aspiring healthcare practices. Implement Sci. 2014; 9:(1)
Johnston C, Burden D, Morris D.London: The Royal College of Surgeons Publications; 2008
Graber TM, Vanarsdall RL, Vig KWL.Missouri: Elsevier Mosby; 2005
Reitan K. Tissue rearrangement during the retention of orthodontically rotated teeth. Angle Orthod. 1957; 29:105-113
de Freitas KMS, Janson G, de Freitas MR. Influence of the quality of the finished occlusion on postretention occlusal relapse. Am J Orthod Dentofacial Orthop. 2007; 132:428.e9-428.e14
Proffit WR. Equilibrium theory revisited: factors influencing position of the teeth. Angle Orthod. 1978; 48:175-186
Dawson PE. Functional Occlusion.Missouri: Elsevier Mosby; 2007
Little RM, Reidel RA, Artun J. An evaluation of changes in mandibular anterior alignment from 10 to 20 years post retention. Am J Orthod Dentofacial Orthop. 1988; 93:423-428
Vanarsdall RL, White RP Relapse and retention-professional and public attitudes. Am J Orthod Dentofacial Orthop. 1990; 98
Shah AA. Postretention changes in mandibular crowding: a review of the literature. Am J Orthod Dentofacial Orthop. 2003; 124:298-308
Tsiopas N, Nilner M, Bondemark L, Bjerklin K. A 40 years follow-up of dental arch dimensions and incisor irregularity in adults. Eur J Orthod. 2013; 35:230-235
Sinclair PM, Little RM. Maturation of untreated normal occlusions. Am J Orthod. 1983; 83:114-123
Blake M, Bibby K. Retention and relapse: a review of the literature. Am J Orthod Dentofacial Orthop. 1998; 114:299-306
Sun J, Yu YC, Chen L Survival time comparison between Hawley and clear overlay retainers: a randomized trial. J Dent Res. 2011; 90:1197-1201
Kumar A, Bansal A. Effectiveness and acceptability of Essix and Begg retainers: a prospective study. Aust J Orthod. 2011; 27:(1)52-56
Hoybjerg AJ, Currier GF, Kadioglu O. Evaluation of 3 retention protocols using the American Board of Orthodontics cast and radiograph evaluation. Am J Orthod Dentofacial Orthop. 2013; 144:(1)16-22
Barlin S, Smith R, Reed R, Sandy J, Ireland AJ. A retrospective randomized double-blind comparison study of the effectiveness of Hawley vs vacuum-formed retainers. Angle Orthod. 2011; 81:(3)404-409
Patel A, Naini F, Gill D. Bonded orthodontic retainers. Ortho Update. 2013; 6:70-77
Schneider E, Ruf S. Upper bonded retainers. Angle Orthod. 2011; 81:(6)1050-1056
Scheibe K, Ruf S. Lower bonded retainers: survival and failure rates particularly considering operator experience. J Orofac Orthop. 2010; 71:(4)300-307

Anterior tooth alignment – recommendations for stability

From Volume 41, Issue 4, May 2014 | Pages 306-312

Authors

Raman Aulakh

BDS, MSc(Orth)

Specialist Orthodontist, Private Practice, The Ashcroft Clinic, Denham, Middlesex, Postgraduate Tutor King's College (MSc Aesthetic Dentistry)

Articles by Raman Aulakh

Subir Banerji

BDS, MClinDent (Prostho), PhD FDSRCPS(Glasg) FCGDent, FDTFEd, BDS, MClinDent (Prostho), PhD, FDSRCPS(Glasg), FCGDent

Articles by Subir Banerji

Email Subir Banerji

Abstract

This article considers the importance of current orthodontic practice in retention and stability when considering anterior tooth alignment.

Clinical Relevance: With the exponential increase of general dentist-based orthodontic systems for anterior tooth alignment, with considerably shorter treatment times, practical recommendations along with a current literature review are required to improve success and outcome of the long-term result.

Article

Anterior tooth alignment seems to be a treatment option preferred by dentists as the non-invasive alternative to destructive tooth preparation for adult patients. Although, from a biological perspective, this may be an ideal way to provide a conservative approach, it is open to controversy, particularly if the treatment time is considerably shortened. The key issues being related to compromised treatment goals, informed consent, clinical consequences of retreatment and long-term stability.1

Anterior tooth alignment is a feasible treatment option for adult patients and constitutes one of the many possible solutions after a thorough orthodontic and aesthetic assessment. The assessment should consist of understanding the patient's chief complaint, performing a thorough evaluation with relevant diagnostic analysis which will allow for the formulation of a problem list from which treatment goals and solutions can be devised. A joint consultation with the patient, restorative dentist and the inclusion of other specialties, if necessary, at the outset may prove invaluable and is to be recommended.

When considering different treatment options, the clinician must be able to explain how the malocclusion affects the patient aesthetically, functionally and biologically. Treatments advocating a long-term improvement in the prognosis of teeth and the stomatognathic system will inevitably be more cost-effective in the long run.

Therefore, case selection for anterior tooth alignment requires a full disclosure of treatment options, with advantages and disadvantages of each treatment plan, before the patient can make an informed and educated decision.

When the decision to embark on an anterior tooth alignment case is made, consideration needs be taken on both the occlusal stability and the retention protocol. This should essentially be at the treatment planning phase and utilize an evidence-based approach to comprehensive orthodontic treatment regarding retention and stability.

A good starting point is by reviewing the findings from the Cochrane Library on ‘Retention procedures for stabilizing tooth position after treatment with orthodontic braces’.2 The study compared Hawley retainers, clear vacuum-formed retainers and fixed retainers, along with the use of the circumferential supercrestal fibrotomy procedure. The review states that there is a lack of robust evidence on which to base clinical practice owing to the inclusion of only five randomly controlled trials in the study. However, the review demonstrates the benchmark for the basis of further studies to improve research and understanding in this field. The answers or lack of answers derived from evidence-based research should be considered with other influences, such as cognitive or political factors, when setting up good practice.3

One of the most useful and easily accessible papers on retention protocol, which supersedes any recommendation made by opinion, is The Royal College of Surgeons' Clinical Guidelines: Orthodontic Retention.4 The approach of the paper is based on sound evidence and looks at occlusion and other factors (such as rotations, spacing, periodontal health, root resorption, lower incisor alignment and position) which may modify retention protocol. This allows the clinician to think of bespoke retention protocols rather than habitual prescription for his/her patient and ask the question: What practical lessons can we learn about retention from comprehensive orthodontics that can help the stability of anterior tooth alignment cases?

To answer this we need to agree on the definition of retention. One of the most complete definitions of retention found in the literature is by Graber et al5 who define retention as ‘… the holding of teeth in optimal aesthetic and functional position.’ There are two factors which affect retention; one being the teeth trying to relapse to their original position and the other is the continuous ageing change of the adult dentition. Therefore, retention protocol needs to take both factors into account by the provision of retainers and by good maintenance of the overall dentition on a long-term basis. The following recommendations are based on opinion, experience and important theories widely accepted in orthodontic literature.

Recommendations for stability

Understand the reasons behind early relapse and be prepared with a plan of action after active orthodontic treatment

Anterior tooth movement, whether it is for mild crowding or spacing, will cause stress and deformation of the attaching fibres in the periodontium. In particular, the collagen fibres of the periodontal ligament fibres and the elastic dento-gingival and inter-dental fibres. Reitan6 demonstrated that it takes up to 8 months for the fibres to remodel once the teeth have been held in the corrected position. Therefore, a strict retention protocol needs to be in place immediately after completion of orthodontic treatment to avoid relapse.

Good finishing reduces the occurrence of relapse, so choose the right cases for anterior alignment

de Freitas et al7 demonstrated, in a study of Class I malocclusions, that the quality of the finished occlusion achieved after orthodontic treatment had an effect on post-treatment relapse. Good orthodontic finishing was directly linked to better long-term stability. Anterior tooth alignment cannot guarantee good occlusal finishing of the whole occlusion; however, attention to case selection for anterior alignment cases reduces the need to compromise a result. Choosing cases with stable intercuspated buccal segments, normal overbite and overjet values with correct functional occlusion is a good start point.

Respect ‘the neutral zone’ and form will follow function

The neutral zone as described by Proffit8 and Dawson9 is based on the principle that teeth will not stay stable where muscles and soft tissues do not want them to be. The neutral zone is the area of balance between the tongue on one side and the buccinators and lips on the other side. Therefore, the strength and position of the peri-oral muscles and tongue will dictate the position and inclination of the anterior teeth. Any large orthodontic movements of the anterior teeth especially associated with an increased overjet may put the teeth in an area of increased instability.

Consider the rationale behind long term retention

The classic studies at the University of Washington by Little et al10 concluded that the orthodontist should not assume that stability will occur after orthodontic treatment. Hence, the only way to ensure continued satisfactory alignment post-treatment is retention for life.11

Frustratingly, when orthodontic relapse does occur, it is most frequently seen in the mandibular anterior segment during the post-retention period.12 The main reason for this development of relapse or crowding is due to the decrease in the dental arch width and length over time; this has been found to occur in treated and untreated subjects.13 Dental maturation changes are inevitable14 and this fact only further confirms the need for long-term retention to improve stability for adult patients.

The start position of for the teeth will help to define a stable end point

Blake and Bibby15 reviewed the orthodontic literature on long-term retention and evaluated the stability of various treatment modalities. Their recommendations, related to determining the final tooth position, are based on well documented studies and listed below:

  • The patient's pre-treatment lower arch form should be maintained during orthodontic treatment as much as possible;
  • Original lower inter-canine width should be maintained as much as possible because expansion of lower inter-canine width is prone to orthodontic relapse;
  • The most stable position of the lower incisor is its pre-treatment position and advancing the lower incisors is correlated with compromising stability.

    • Pre-restorative orthodontics and anterior tooth alignment

    The true value of all pre-restorative orthodontics is to reduce the amount of invasive dentistry required and increase the longevity of any restorative work planned. The success of alignment and additive bonding as a minimally invasive approach will depend on long-term stability. If the anterior teeth relapse, there could be a change in the functional occlusion and this could result in the failure of the additive bonding and an unhappy and aggrieved patient. Retreatment will have both financial and biological implications.

    Additive bonding should be used to enhance the aesthetic result and, where possible, the functional occlusion. This, combined with a correct retention programme, will increase the outcome of success from an orthodontic and restorative perspective. This will be demonstrated in the case report that follows.

    The retention programme

    The provision of the type of retainers prescribed to a patient is bespoke for each individual case as recommended in the RCS guidelines mentioned earlier.4 The initial malocclusion and the state of the overall dentition also need to be taken into account when creating a retention protocol. The main types of retainers used are fixed, such as the bonded retainer, or removable, such as the Hawley, Begg or Essix retainer. Experience has shown that the provision of two retainers per arch reduces the dependency on relying on one retainer, which may get damaged or lost over a period of time.16

    So which retainer should you use when?

    A recent study has evaluated the difference in the clinical effectiveness of either using an Essix or a Begg retainer17 and concluded that they are both as effective as each other. However, there was a better patient acceptance of the Essix retainer in terms of appearance. Another comparative study18,19 compared the amount of relapse after the use of the Essix retainer and the Hawley retainer; both performed in a similar manner of clinical effectiveness.

    However, there are specific indications when a fixed retainer has been deemed to be more beneficial than a removable retainer.20 These are listed below:

  • Orthodontic space closure;
  • Severe rotations;
  • Severely displaced teeth;
  • Loss of periodontal support;
  • Planned alteration in the lower inter-canine width;
  • Advancement of lower incisors during active treatment;
  • After correction of deep overbite.

    • Many of the above scenarios are common in anterior tooth alignment, therefore it is important for dentists to have this retainer option available for their patients. The technique for the placement of the bonded retainer needs to be perfected, as failure rates can be associated with the skill of the operator.21,22

    As well as the provision of retainers, patients should be supervised for at least six months to help guide them into their retention programme. This should be combined with patient education and written consent to help consolidate the retention protocol.

    Case report – thinking of stability before you align

    A fit and healthy 35-year-old woman was referred to the orthodontist from her GDP. The patient had initially asked her GDP for a ‘Hollywood smile’ with veneers to improve her smile and anterior incisor alignment. The GDP recommended that she sought an orthodontic opinion for an ortho-restorative approach with minimally invasive dentistry.

    A full aesthetic and orthodontic assessment was carried out and a medium lip line was noted which masked the recession on the upper right canine tooth. The patient presented with a Class II division 2 incisor relationship on a mild Class II skeletal base with a high angle tendency. The overjet was 2 mm and overbite decreased but complete. The buccal molar segments were tightly inter-cuspated in a Class II occlusion on both sides. The canines were also in a Class II relation and involved in canine guidance on the left side and group function on the right. There was moderate crowding in the upper arch and mild crowding in the lower. There was a tooth size discrepancy associated with small upper laterals which were involved in a lip catch and drifting over time. The position of these lateral incisors contributed to the smile arc alignment that could benefit from improvement (Figure 1).

    Figure 1. (a–d) Pre-treatment clinical photographs.

    Four treatment plans were presented and explained to the patient with the referring GDP. These took into account the options of extraction versus non extraction as well as correction or acceptance of the tooth size discrepancy. Three types of orthodontic appliances (ceramic braces, lingual braces and clear aligners) had been offered to the patient. The choice of Invisalign fulfilled the patient's aesthetic needs and met the orthodontist's needs in terms of movements required, which included rotation correction, overbite and torque control. The use of the Clincheck software was a useful tool to communicate and relay information.

    Treatment goals based on stability recommendations:

  • Maintain good buccal relations and group function on the right side and canine guidance on the left by minimal movement of molar and canine teeth.
  • Improve overall arch form without unnecessary expansion and flaring of arches (Figure 2: Clincheck images of before and after demonstrating the control of tooth movements and occlusion).
  • Align anterior teeth whilst maintaining the overjet and overbite within normal values to provide best aesthetics, function and stability (Figure 3: Clincheck images demonstrating the importance of IPR for overjet control).
  • Provide the best pre-restorative position of anterior teeth to allow for minimal bonding. Additionally to improve the tooth size discrepancy associated with UL2 and UR2 by selective interproximal reduction stripping (IPR). IPR was performed on the upper central incisors and canines whilst omitting the already small upper lateral incisors. This allowed for an improvement in the TSD and utilizing the space for overjet control (Figure 4 showing Clincheck treatment planning for IPR scheme).
  • Long-term retention by use of fixed retainers in both arches, especially due to rotations on UL2 and UR2. This would be combined with removable Hawley retainers to be worn at night to help maintain new arch form and as a back-up retainer.
    • Figure 2. Clincheck images: (a) before treatment (left buccal view); (b) after treatment (left buccal view). (c, d) Superimposition of before (dark blue) and after result (white) of upper and lower occlusal views.
    Figure 3. Clincheck images: (a) overjet prior to alignment; (b) overjet after alignment without IPR; (c) overjet after alignment with IPR.
    Figure 4. 0.25 mm IPR from mesial and distal contact points (total 0.5 mm), 0.3 mm from mesial contact point only, 0.3 mm from distal contact point only.

    Treatment plan

  • Invisalign upper and lower arches;
  • Selective IPR to improve overjet and correct tooth size discrepancy;
  • Additive incisal bonding to improve aesthetics of anterior incisors;
  • Retention with fixed and removable retainers in both arches.

    • Treatment summary

    The treatment time was 12 months, requiring 23 aligners in the upper and 12 in the lower. Power ridges were used for torque control of the upper central incisors. Refinement aligners were used for detailing the final position of the upper laterals (Figure 5: final orthodontic result and corresponding Clincheck showing the pre-restorative position of the incisors which could now benefit from minimal intervention dentistry with additive composite bonding).

    Figure 5. (a, b) Final orthodontic result.

    The final post-orthodontic and restorative result has achieved the treatment goals set earlier. A good aesthetic result has been achieved with function and stability kept in mind from the start (Figure 6).

    Figure 6. (a–d) Final post-orthodontic and post-restorative result.

    Conclusion

    Anterior tooth alignment primarily aims at improving dentofacial aesthetics; however, it should not compromise stomatognathic function or place teeth in a position of instability. For this reason, case selection is an important factor associated with anterior tooth alignment cases. The overall assessment, treatment planning and retention protocol should be as vigilant as that set for comprehensive orthodontic and restorative treatment in order to ensure long-term stability.