The present case cohort assessed the clinical performance of a regenerative strategy developed to increase clinicians’ ability to optimize the outcomes of regenerative periodontal surgery. The overall rationale for the proposed clinical approach comes from the recognition that the different regenerative approaches reported in the literature frequently lead to unsatisfactory and rather unpredictable outcomes.

The proposed protocol (Figs. 1 and 2) is mainly based on different levels of scientific evidence and partly on the clinical experience of the authors. The published evidence allows us to clearly identify, and therefore to control, some of the factors that negatively influence the clinical outcomes of periodontal regeneration.

Patient-associated factors such as plaque control, residual periodontal infection, and smoking have been shown to have a consistent negative impact on both short- and long-term results. An ideal protocol for regenerative surgery should, therefore, include enough non-surgical periodontal therapy to minimize the impact of supragingival plaque and bacterial infection and smoking cessation protocols. Obtaining a high level of cooperation from the patient is also key: regenerative therapy requires a substantial contribution from the patient, in terms of compliance with a series of behavioral recommendations, modified oral hygiene methods, and topical and systemic medications.

Among the technical/surgical-associated factors, lack of primary closure of the interdental space and consequent bacterial contamination of the regenerating wound represents one of the most significant factors leading to compromised outcomes of regenerative surgery. An important element for improving regenerative outcomes is achieving and maintaining primary closure of the flaps in the critical interdental area. Modified flap designs allowing access to the defect area while preserving the interdental papilla have been shown to improve the ability of clinicians to obtain this goal, especially when used with a microsurgical approach. In the present study, the MPPT and the SPPF were used according to original indications: the MPPT to access wide interdental spaces (>2 mm) and the SPPF to access the narrower ones.

Selection of the regenerative strategy was based on some evidence and on some assumptions. Wide and non-supportive defects were treated with self-supporting membranes or with bioabsorbable barriers supported with a filler material. Our rationale was to avoid as much as possible the collapse of the barriers and of the overlying soft tissues into the coronal part of the defect. Such an occurrence is generally expected to reduce the space for regeneration and enhance the soft tissue recession. When defects were narrow and presented with a predominantly 2- or 3-wall morphology, a bioabsorbable barrier was used, assuming that the residual walls would prevent collapse of the barrier and soft tissues. In the 3-wall defects EMD was preferred based on evidence showing a positive response of 3-wall defects to EMD, which was also associated with a minimal impact of post-surgical complications.

Primary closure of the flaps was ensured by using a two-layer suturing technique. It consisted of a deep internal mattress suture aimed at coronal advancement of the flap and controlling flap tension, and of a more superficial internal mattress suture to close passively the interdental papilla.

A stringent post-surgical regimen was enforced to control bacterial contamination. A recent systematic review reports a significant PD reduction and an advantage in terms of CAL gains when a stringent postoperative plaque control regimen is followed.

The use of this decision-making protocol resulted in 6 ± 1.8 mm of CAL gain at 1 year in defects with an intrabony component of 6.6 ± 1.7 mm; CAL gain was 92.1% ± 12%. This indicates that a large part of the intrabony component of the defects was resolved. Using the Ellegaard and Löe criteria, resolution of the intrabony component of the defect was either satisfactory or complete in all treated cases. In particular, 40.5% of defects had attachment level gains equal or greater than the baseline depth of the intrabony component, while the defect with the worst response showed a 71.4 CAL%. Historical comparison with clinical experiments using bone grafting or GTR clearly indicates that the results of this trial are in the top percentiles in terms of CAL gains and defect resolution. To properly interpret these results, it is important to emphasize that several factors influence the clinical outcomes of periodontal regeneration. The case selection process excluded cases with sub-optimal patient-associated factors such as plaque control, residual bleeding on probing, or cigarette smoking.

Furthermore, the surgical procedures and regenerative materials used have been associated with a degree of sensitivity to the skills of the surgeon. In this respect, clinicians should not attribute the observed results to the choice of the regenerative strategy alone.

The increment in recession of the gingival margin between baseline and 1 year was only −0.1 ± 0.7 mm. This excellent result could be related to the interdental soft tissue preservation, the non-traumatic manipulation during surgery favored by the use of microsurgery, and the selection of the appropriate regenerative strategy which limited soft tissue collapse. The optimal clinical outcomes obtained with this approach are further underlined by the shallow residual probing depths of 2.7 ± 0.6 mm observed. These are relevant observations since one of the goals of regenerative treatment of intrabony defects is reduction of PD while causing minimal gingival recession.

Regarding primary closure of the flaps, it was technically possible to achieve complete primary closure in 100% of the treated interdental sites. Closure was maintained in 90% of cases for the entire healing period. Under these circumstances, it is reasonable to assume that wound healing occurred in a sealed environment with minimal levels of bacterial contamination and optimal stability of the wound. It is also evident that the ability to obtain and maintain primary closure allows optimal retention and biological activity of materials applied into the wound environment to differentially modulate the healing process.

This study was not intended to compare different regenerative approaches, but rather to give a rationale for the application of the different materials according to best clinical judgment. The results of the four groups of therapy, according to the regenerative material employed, show that each of the materials performed very well, with excellent clinical outcomes. This is especially evident in terms of percent clinical attachment gain. CAL% ranged from an average 95.4% ± 12.9% and 94.7% ± 13.4% with EMD and with titanium reinforced ePTFE membranes, respectively, to an average 88.9% ± 11.5% and 88.2% ± 9.6% obtained with bioabsorbable barriers alone and with bioabsorbable barriers supported by a bone replacement graft, respectively. Gingival recession observed and residual PD in each group were also minimal. The different morphology of the defects when a specific technology was applied, however, does not allow a comparative assessment in terms of performance since some of the morphologies are thought to represent greater clinical challenges than others. In conclusion, the use of the proposed regenerative strategy resulted in large amounts of clinical attachment level gains and minimal recessions at 1 year in all of the treated population and in each of the four treatment groups. It is, therefore, possible to suggest to clinicians wishing to optimize clinical outcomes of periodontal regeneration in intrabony defects to incorporate the operative strategies described in this study in their clinical decision making.