Step 3 for the treatment of periodontal diseases: non-regenerative periodontal surgery

Periodontitis is major public health problem. It is the sixth most prevalent disease, making it the most common chronic inflammatory non-communicable disease of humans,¹ affecting an estimated 743 million adults globally. The Global Burden of Disease 2017 study estimated that 11.2% of the population has severe periodontitis, with that figure shown to be increasing.² The prevalence of mild to moderate disease is almost up to 50%, and higher (60%) in patients over 65.³ It accounts for a substantial amount of tooth loss and disability owing to the impact on aesthetics, chewing function, social inequality and quality of life. It untreated or inadequately treated, more years are lost to disability from periodontitis than from any other disease. In addition, on a global scale, economic analysis has shown that it is the third most costly disease behind diabetes and cardiovascular disease.⁴

With the development of new guidelines supported by more evidence, we could say that we know more about periodontitis over the past decade than ever before. Periodontitis is a complex chronic inflammatory disease, which, in susceptible patients, is mediated by a dysregulated, hyper-responsive and destructive immune inflammatory response. It is characterized by marginal bleeding, pocketing, clinical attachment loss and radiographic signs of alveolar bone loss.⁵ It is largely driven by genetics and lifestyle factors that may interact to result in a host response and disease pattern specific to an individual patient. Furthermore, sites may show different levels of damage and correspondingly different responses to treatment owing to patient, tooth and site-specific factors. We need to therefore consider different treatment approaches as we progress through the periodontal treatment pathway. European guidelines6 have outlined evidence-based treatment strategies and these guidelines have been adapted by the British Society of Periodontology.⁴

This article provides an overview of the key evidence-based recommendations to implement when considering patients entering into step 3 of the periodontal treatment pathway, specifically the non-regenerative surgical considerations.

What are the aims of step 3?

The latest treatment guidance is based on a ‘stepwise’ approach to treatment, meaning that it should be carried out in an incremental manner. After establishing adequate oral hygiene practice, identifying and controlling patient risk factors and professional supra- and subgingival professional mechanical plaque removal (PMPR) in steps 1 and 2, the patient's response to treatment is re-evaluated. A large proportion of sites may be expected to respond to initial non-surgical treatment alone (74%).^7,8 The third step of periodontal treatment is aimed at treating those sites that have not responded adequately, targeting non-responding or residual deep pockets (pockets >6 mm). The purpose is to achieve access to root surfaces associated with these residual pockets for further subgingival instrumentation, aiming to possibly partially regenerate or more likely eliminate those elements that add complexity to the management of periodontitis (such as infrabony defects, root concavities and furcations).⁴ Tooth- and site-level risk factors are considered at localized areas where residual pockets remain, and a decision made on the best approach for managing either residual shallow pockets (4–5 mm) or residual deep pockets (>6 mm). In these areas, further treatment should be implemented with the aim of stabilizing disease and improving the chances of retaining teeth. The ultimate aim is to prevent further disease progression, reduce gingival inflammation, deep pockets and regain periodontal attachment to ultimately prevent tooth loss, loss of function and the negative effects on general health. The objectives can be met with non-surgical and surgical phases of periodontal treatment (Figure 1).

Why do deep residual pockets matter?

Deep residual pockets form favourable ecological niches for dysbiotic biofilms and are at higher risk of disease progression if left untreated or without regular supportive periodontal care (SPC).⁸ Other factors also need to be considered at a tooth- and site-specific level, such as the presence of furcations, grooves, infrabony defects, the anatomy of the gingival tissue and the access for oral hygiene. These factors will increase the complexity of management and the treatment options to consider, because these sites may be more likely to be unstable if left untreated.

Compared with residual shallow pockets (4 mm), the depth of the residual site after active therapy can be considered as a predictor of tooth loss during SPC (5 mm, OR = 7.7; 6 mm, OR = 11.0; >7 mm, OR = 64.2).⁹ Matuliene et al also showed that deep pockets (>6 mm with bleeding) had a 30% higher chance of tooth loss during long-term SPC. A more recent study showed similar figures for patients with stage IV disease.¹⁰ During SPC, the presence of residual pockets >5 mm increased the risk of disease recurrence.¹¹ Jenkins et al showed that between 20.5% and 28.6% of deep pockets (>6 mm) had a higher rate of disease progression (clinical attachment loss (CAL) >2 mm) in 12 months compared with shallow sites of 4–5 mm (11.6–11.8%).¹² Cortellini et al also showed the highest rates of disease recurrence in pockets >5 mm in a randomized control trial comparing periodontal regeneration and access flap surgery over a 20-year follow-up period.¹³

At a broader mouth level, the number of residual sites can also help to assess the level of stability and risk of disease progression. The presence of some shallow sites (fewer than four sites with 5-mm pocket depths) has been deemed consistent with disease control,¹⁴ and in severe disease, only a relatively small percentage (20%) of patients could be classified as stable according to the classification criteria (probing pocket depth (PPD) <4 mm with no bleeding on probing and bleeding score (BS) <10%).^15,16 Several sites may therefore need monitoring, site-specific oral hygiene, and regular professional instrumentation. We need to consider what can be maintained, what cannot, what is likely to progress and what further advanced treatment is indicated. In some cases, these treatment modalities may need referral to a level 2 or 3 practitioner.

Factors to consider before considering periodontal surgery

Not all residual pockets require surgery, and in addition to the patient's suitability for surgery (relevant medical history), a holistic approach to treatment planning should be adopted. Considerations should be given to the indications, aims and suitability for surgery, and it may be helpful to consider the following simple questions:

• How soon after active periodontal treatment has the re-evaluation been carried out?
• Has the non-surgical treatment been adequate?
• Are the root surfaces rough? Can subgingival calculus deposits be detected?
• Has the patient's oral hygiene been adequate (plaque score)?
• Is the oral hygiene at that site adequate?
• Are they using the correct technique (has this been demonstrated)?
• Is it easy enough to access (anterior tooth/posterior/multirooted/furcations/grooves?)
• Are there anatomical factors that make access difficult (e.g. thick fibrous tissue, shape of gingival architecture)?
• Is there furcation involvement and the patient cannot access it easily enough to clean?
• Are they struggling due to dexterity? If so, will they be able to maintain it after periodontal surgery?
• Is it a deep pocket with an infrabony component that cannot be managed without surgery?
• Is there something else going on (consider endodontic status, the presence of root fractures)?
• What is the restorative status of the tooth?
• What is the strategic importance of the tooth?

High-quality, repeated subgingival instrumentation should be considered for residual pockets of 4–5 mm. Consideration should be given for repeat subgingival instrumentation, particularly if there is no added complexity, and if the judgement is unclear, specialist expertise and advice should be sought.⁴ It is also important to remember that some residual pockets, even up to 5 or 6 mm, in the absence of bleeding on probing, may not represent active disease,¹⁴ and could be maintained for a long time with good oral hygiene and a well-structured supportive periodontal care programme.

The rationale for step 3

There is a consistent body of evidence showing that subgingival debridement is effective in reducing pocket depths, bleeding on probing and gaining clinical attachment.¹⁷ Recent systematic reviews have shown a weighted pocket depth reduction of 1.4 mm and the proportion of pocket closure estimated at 74%.¹⁸ However, it can be difficult to fully instrument the root surfaces, especially in the presence of complex anatomy. Indeed, in vitro studies have shown that more hard deposits are detected in deep sites (PPD >5 mm) and at molars (particularly furcations) than at single-rooted teeth.¹⁹ While non-surgical phases of periodontal treatment are often successful in controlling periodontal disease, in sites with persistent inflammation and deep pockets, surgical treatment modalities are often considered the next phase or step in treatment to overcome the limits of what can be achieved with closed subgingival debridement.²⁰ At these localized sites, the main objective of periodontal surgery is to improve direct vision and access for professional instrumentation, to reduce or correct anatomical factors and ultimately create an environment that is easy and comfortable for the patient and the clinician to maintain.^20,21

General considerations for step 3

The NHSE Commissioning standard for Restorative Dentistry (OCDO 2019) and the BSP Good Practitioners Guide outline some of the basic principles when considering periodontal surgery. This is detailed in the BSP implementation of the EFP guidelines. Surgery is not normally undertaken following a single phase of non-surgical periodontal treatment (NSPT). The outcomes are reviewed, and NSPT repeated in engaged patients. In non-engaged patients, surgery is contraindicated. With any surgical procedure, the indication to treat needs to be subject to patient consent, an evaluation of risks versus benefits, and any medical contraindications should be considered.²¹ Periodontal surgery should not be performed in patients who are not achieving adequate levels of oral hygiene.⁶

Options for treatment at step 3

Different surgical approaches have been suggested to treat the residual pockets, with the options being:

• Repeated subgingival instrumentation with or without adjunctive therapies;
• Access flap periodontal surgery;
• Resective periodontal surgery;
• Regenerative periodontal surgery.

In this article, the evidence base for access flap and resective periodontal surgery is reviewed in more detail.

Access flap procedures

Access flap (AF) procedures were introduced to improve the efficacy of subgingival debridement by gaining direct access to the root surface, root concavities and furcations, previously inaccessible with closed debridement. This facilitates better disruption of biofilm, removal of calculus and granulation tissue. Access flaps are typically conservative surgeries where no active removal or reshaping of alveolar bone (ostectomy or osteoplasty) is carried out and there is no or minimal resection of soft tissues. The treatment focuses on improving access and vision, to enhance the ability to clean the root surfaces and anatomical variations encountered.

Conservative access flap procedures access root surfaces without eliminating significant amounts of hard and soft tissue. These procedures have been classified depending on the amounts of marginal gingivae and interdental papillary tissue removed:

• Open flap instrumentation (intra-sulcular incisions, OFD);
• Minimally resective flaps with para-marginal incisions (e.g. modified Widman flap, MWF);
• Papilla preservation flaps (MIST).

A variety of access flaps have been described from OFD,²³ minimally resective flaps such as the MWF,²⁴ and minimally invasive surgical techniques (MIST) (Figure 2). In the MWF, an inverse bevel incision is used to remove marginal tissue to eliminate the pocket's epithelium and remove the inflamed tissue from the inner aspect of the flap. The original design of the MWF was as an access flap surgery; however, the procedure involves minimal soft tissue resection to allow healing by primary intention. In these cases, one may expect a reduction in pocket depths through a combination of pocket closure, clinical attachment gain and mild recession.^25,26

Minimally invasive surgical techniques (MIST), on the other hand focus on papilla preservation in treating infrabony defects, enhancing blood clot stability.²⁷ These include the modified papilla preservation technique, simplified papilla preservation, and modified minimally invasive surgical technique (M-MIST). These conservative approaches have also been shown to reduce morbidity and have more comfortable post-operative recovery. Traditional periodontal approaches, such as OFD/MWF or resective surgeries, were frequently associated with recession, which impaired patient satisfaction in terms of aesthetics. Studies have shown gingival recession of up to 2 mm compared to 0.48mm for MIST. With minimal flap reflection, the approach adopts gentler handling of tissues, allowing better wound stability and the maintainance of gingival architecture, better revascularization of the tissues during early wound healing and an increased stability of the blood clot. This is critical for the improved outcomes and patient satisfaction seen with these less invasive approaches.²²

How effective are access flaps compared to repeated non-surgical instrumentation?

More than two decades ago, the concept of a ‘critical probing depth’ defined a threshold (around 5.4 mm) above which periodontal surgery resulted in greater reductions in probing depths and clinical attachment gain compared with non-surgical treatment²⁸ indicating that deep pockets >6 mm showed improved gains.²⁰ A recent systematic review and meta-analysis showed similar outcomes for stage III periodontitis patients. Access flaps showed greater probing depth reductions than subgingival debridement (PMPR) at 1 year. The relative effect was 27.5%. The PPD difference was more pronounced at deeper sites (PPD >6 mm) and in pockets with infrabony defects. A significantly higher percentage of shallow pockets was achieved with AFs than with subgingival instrumentation with fewer sites needing re-instrumentation (8–29% vs 0–14%) in the AF group. For residual deep pockets (PPD >6 mm), the recommendation is to perform access flap surgery. In moderately deep sites (4–5 mm), CAL gain was significantly greater with subgingival instrumentation and access flaps in these sites resulted in more attachment loss. For patients with moderately deep residual pockets (4–5 mm), repeated subgingival instrumentation is recommended.²⁷ Whichever mode of treatment is selected, the level of oral hygiene and maintenance is a key critical factor in success (Figure 3).

How effective are access flaps compared to repeated non-surgical instrumentation?

More than two decades ago, the concept pf a ‘critical probing depth’ defined a threshold (around 5.4mm) above which periodontal surgery resulted in greater reductions in probing depths and clinical attachment gain compared with non-surgical treatment²⁸ indicating that deep pockets >6 mm showed improved gains.²⁰ A recent systematic review and meta-analysis showed similar outcomes for stage III periodontitis patients. Access flaps showed greater probing depth reductions than subgingival debridement (PMPR) at 1 year. The relative effect was 27.5%. The PPD difference was more pronounced at deeper sites (PPD ≥6mm) and in pockets with infrabony defects. A significantly higher percentage of shallow pockets were achieved with access flaps than with subgingival instrumentation, with fewer sites needing re-instrumentation (8–29% vs 0–14%) in the access flap group. For residual deep pockets (PPD ≥6 mm), the recommendation is to perform access flap surgery. In moderately deep sites (4–5 mm), CAL gain was significantly greater with subgingival instrumentation and access flaps in these sites resulted in more attachment loss. For patients with moderately deep residual pockets (4–5 mm), repeated subgingival instrumentation is recommended.²⁷ Whichever mode of treatment is selected, the level of oral hygiene and maintenance is a key critical factor in success.

How effective are different access flap procedures?

In one systematic review assessing the clinical performance of access flaps in the treatment of infrabony defects, the average PPD reduction was 2.77 mm, the percentage reduction was 41.63% and the mean probing depth reduction was 4.18 mm. The results of this review suggest that in infrabony defects, access flaps are a valid surgical approach.²¹ However, there are a limited number of studies comparing different access flap procedures. Out of the three available studies comparing MWF with OFD, only one showed statistically significant greater PPD reductions for MWF than OFD. There were no statistically significant differences in the percentage PPD reduction comparing papilla preservation flaps (single flap approach) and conventional flaps (only one study). There is therefore insufficient evidence on the choice of flap procedure after NSPT, and access flap surgery may be carried out using different flap designs.

Resective flaps

Access flaps aim to allow visual access with minimal reduction in the shape and anatomy of the soft tissues. Resective flaps include pocket reduction/elimination surgeries that, in addition to gaining better vision access for subgingival instrumentation, aim to change the shape and architecture of the hard and/or soft tissues in order to achieve a more controlled PPD reduction (Figure 4).

How effective are resective flaps (pocket elimination/reduction) in comparison with access flap surgery?

In stage III periodontitis patients, with deep residual pockets (PPD ≥6 mm), resective flaps are more predictable than conservative access flap procedures in achieving shallower pockets and the intended end points to allow long-term maintenance of teeth.^4,29 The available evidence suggests that resective surgery achieved better probing depth reductions (WMD = 0.59 mm) than access flaps in the short term (6–12 months), but no long-term differences in CAL gains were observed after a longer period of 3–5 years.²⁹ However, gingival recession is greater with resective surgery than access flaps. The risk of recession needs to be considered in each individual case, particularly where it may have an aesthetic impact for the patient. The data on patient-reported outcome measures (PROMS), the percentage residual pockets or the need for re-treatment were not reported in any of the studies (Figure 5).

Resective surgery and furcations

Residual pockets in mandibular class II and maxillary buccal class II furcation involved teeth may be treated with regenerative surgery.³⁰ However, in Class III furcation defects, multiple class II furcations on the same tooth and maxillary interdental class II defects, in addition to non-surgical instrumentation, access flap procedures may be carried out to allow access for tunnelling, root separation or root resection.

The choice of root separation or amputation depends on the location of pathology or residual pocket depth. Over a 10-year follow–up, Carnevale et al showed 93% survival rates with root resection procedures and tunnel procedures showed 52–92% success rates with most teeth being lost due to caries,³¹ endodontic pathology or root fracture and not progression of periodontitis.³² In a more recent systematic review, survival had ranges of 38–94.4% (root resection) and 62–67% (tunnelling), 63–85% (OFD) and 68–80% (SRP). Overall treatment provided better results for class II than class III furcations. The data indicate overall similar survival rates for resective surgery compared with subgingival instrumentation and access flaps (OFD) (Figure 6).

To determine the most appropriate type of procedure, the clinician should consider other criteria beyond the class of furcation involvement, such as the degree of bone loss and surgical accessibility for the clinician together with the ability of the patient to perform good oral hygiene in the area.³³

General recommendations for periodontal surgical procedures

Additional specific training is required to carry out advanced periodontal surgery and it should be carried out by dentists with additional training or by specialists in referral centres in primary or secondary care. The BSP supports additional efforts to improve access to this level of care for these patients. If expertise is not available, or referral is not an option, repeated subgingival instrumentation of the area is recommended with or without access flaps. A programme of frequent supportive periodontal care that includes regular subgingival instrumentation and review of oral hygiene measures is essential.⁴ In addition, a strong consensus of expert opinion, based on decades of research studies and clinical expertise, recommends not performing periodontal surgery in patients who do not achieve and maintain adequate self-performed plaque control. Several proof of principle studies have shown the negative effects of performing periodontal surgery in patients with inadequate oral hygiene.^34,35 These studies showed that, irrespective of the type of treatment carried out, establishing good oral hygiene prior to surgery, and plaque control during the supportive phase, were critical factors in the outcome of surgery. In Nyman's classic ‘plaque-infected dentitions’ study, negative effects were in fact observed (clinical attachment loss) in patients who did not maintain adequate plaque control. Plaque scores less than 20–25% have been consistently associated with better surgical outcomes.

Summary

The purpose of non-regenerative surgery is to obtain access to surfaces with residual pockets for further subgingival instrumentation, aiming to possibly regenerate or resect those lesions that add complexity to the management of periodontitis. At these localized sites, the main objective of periodontal surgery is to improve direct vision and access for professional instrumentation, to reduce or correct anatomical factors, regenerate lost periodontal tissue where possible, and ultimately create an environment that is easy and comfortable for the patient and the clinician to maintain

For residual deep pockets (PPD ≥6 mm), the recommendation is to perform access flap surgery. In moderately deep sites (4–5 mm), CAL gain was significantly greater with subgingival instrumentation, and access flaps in these sites resulted in more attachment loss. For patients with moderately deep residual pockets (4–5 mm), repeat subgingival instrumentation is recommended.²⁷

There is insufficient evidence on the choice of flap procedure after NSPT, and access flap surgery may be carried out using different flap designs. However, previous data suggest that minimally invasive surgical techniques provide improved patient satisfaction with less discomfort and recession.

In stage III periodontitis patients, with deep residual pockets (PPD ≥6 mm), resective flaps are more predictable than conservative access flap procedures in achieving shallower pockets and the intended endpoints to allow long-term maintenance of teeth.^4,29 However, recession must be considered.

Whichever mode of treatment is selected, the level of oral hygiene and maintenance is a key critical factor in success.