Treatment of Gingival Recession Using the Pinhole Surgical Technique With Collagen Membrane Vs Coronally Advanced Flap Technique With Connective Tissue Graft: A Split-Mouth Randomized Clinical Trial

Gingival recession is a common finding among adult populations and is often associated with esthetic concerns, increased tooth sensitivity, and higher risk for root caries.^1-3 Over the past 70+ years, surgical techniques to increase soft-tissue coverage of exposed root surfaces have been proposed and modified. These techniques include free gingival graft,^4,5 connective tissue graft (CTG),⁶ pedicle flap,^7,8 coronally advanced flap (CAF),^9-13 and guided tissue regeneration.¹⁴ These methods may be used with or without acellular dermal matrices, enamel matrix protein derivatives, xenogeneic collagen matrices, and other biological materials, each offering different levels of complexity and varying degrees of success.^15,16

Among surgical techniques, CTG with CAF is considered the "gold standard" method for the treatment of gingival recession.¹⁷ CTG technique offers excellent graft healing provided by the bilaminar blood supply coming from the recipient bed and the overlying flap. CTG also provides a good chromatic integration of the graft with favorable esthetic outcome. In addition, CTG demonstrates an increase in thickness of gingival tissue and width of keratinized gingiva, as well as the potential for creeping attachment.¹⁵ Nevertheless, CTG is associated with an additional pain source and increased morbidity due to the use of a secondary surgical site to harvest donor tissue.¹⁸

The pinhole surgical technique with the use of collagen membrane (PST + CM) is a relatively recent modification of the pedicle flap procedure.¹⁹ PST + CM involves the separation of the gingiva with its periosteum from the underlying bone through the creation of a small pinhole in the vestibular area of the involved teeth. Strips of hydrated bioresorbable collagen membrane are used to fill the space created underneath the undermined interproximal papilla and support the overlaying flap. The result is that the gingival tissue and its blood supply are preserved while the mucoperiosteal flap is freed from its apical attachment to aid in coronal advancement and adequate root coverage. Moreover, this technique does not require a secondary surgical site and minimizes trauma to the gingival tissue by eliminating suturing to stabilize the flap margin coronally, as stabilization is instead accomplished by internally packing the surgical site with strips of bioresorbable collagen membrane.

Despite the advantages of PST + CM, no well-designed randomized clinical trials have been published in the literature showing head-to-head comparison of this technique against others. The aim of this study, therefore, is to compare the 1-year outcomes of the treatment of gingival recession defects using PST + CM versus CAF + CTG.

Materials and Methods

Study Design and Approval

This investigation used a randomized, single-blinded, split-mouth study design. Subjects were recruited from the clinics of the University at Buffalo School of Dental Medicine. The study protocol was approved by the Institutional Review Board (IRB) Committee, State University at Buffalo, New York (project number 00001141, ClinicalTrials.gov registry number NCT04356391). The study was conducted between March 2018 and February 2021.

The aims of the study and details of the methods and surgical procedures were explained to eligible patients, and a comprehensive examination was performed, including a complete medical and dental history, periodontal charting, and full-mouth radiographic examination taken with an intraoral x-ray unit (Heliodent Plus, Dentsply Sirona, dentsplysirona.com). Subjects who volunteered to participate signed a written informed consent.

Study Subjects

The inclusion criteria represented patients ≥18 years of age with no missing teeth in the premolar-to-premolar region, having at least two contralateral incisors, canines, or premolars with Miller's class I or II (Cairo's recession type 1) gingival recession defects of ≥2 mm,²⁰ and having donor tissue thickness of at least 1.5 mm. Participants agreed to be compliant with periodontal recall appointments and oral hygiene instructions. The exclusion criteria included current smokers, history of periodontal surgery at the involved sites in the past 24 months, presence of systemic diseases, presence of conditions or behaviors that may affect the outcome of periodontal therapy such as uncontrolled diabetes mellitus, immune deficiencies, pregnancy, or lactating women, and patients with history of allergic reaction to collagen.

An investigator who was not involved in either the surgical procedure or the examination performed patient allocation. Two contralateral teeth with recession defects were randomized to one of the following treatments: (1) pinhole surgical technique with the use of collagen membrane (PST + CM, n = 36); (2) coronally advanced flap with connective tissue graft (CAF + CTG, n = 36).

Sample Size Calculation

The primary outcome of the present study was the recession reduction (RR). For the sample size calculation, a difference of 0.5 mm between groups after 1 month was considered significant. Twenty-five recession sites per group (a total of 50 recession sites) would be necessary to provide a power of 80% with a significance level of 0.05 and a standard deviation (SD) of 1 mm. Thirty-six recession sites were included in each group to account for anticipated dropouts.

Surgical Procedures

Each subject was provided with individualized oral hygiene instructions prior to the start of treatment. Faulty oral hygiene practices and other behaviors that may have caused or contributed to the development of the recession defects were identified, and appropriate measures were taken to eliminate or control these factors when indicated. Scaling and root planing was performed as needed. The surgical procedures were scheduled 2 weeks after adequate oral hygiene (plaque index <15%) and control of gingival inflammation (gingival index <15%) were achieved.²¹

The surgical procedures were performed under local anesthesia using 2% lidocaine with 1:100,000 epinephrine. The recession defects were thoroughly scaled using curettes (Gracey Curettes, HuFriedyGroup, hufriedygroup.com), and any root surface deposits, soft cementum, root prominences, or other irregularities were eliminated to allow for proper graft adaptation and adequate blood supply.

The test sites were treated by the PST + CM technique.¹⁹ A small horizontal incision (ie, pinhole) was made in the alveolar mucosa apical to the mucogingival junction of the affected tooth, and the flap was then undermined to create a full-thickness mucoperiosteal pouch, followed by extending the pouch horizontally and coronally to undermine the adjacent papilla and free the flap for its coronal displacement. Multiple 2-mm x 12-mm strips of resorbable collagen membrane (Bio-Gide^®, Geistlich Pharma AG, geistlich.com) were packed under the papilla to secure the flap in a coronal direction. Gentle pressure was applied for 5 minutes to minimize the thickness of postoperative blood clot. No sutures were utilized to immobilize the tissues.

The teeth allocated to the CAF + CTG group received the treatment as previously described in the literature.^6,21-24 This consisted of the placement of a CTG from the palatal donor site directly over the exposed root and advancement of the flap coronally for coverage of the graft. First, a sulcular incision was made excluding the papilla, followed by sharp dissection extending 3 mm to 5 mm laterally and apically to the recession area, creating a supraperiosteal partial-thickness flap that would extend beyond the mucogingival junction while keeping the tip of the interproximal papillae attached to the teeth below the proximal contact point. The CTG was then harvested from the palate as described by Bruno.²¹ After being harvested, the graft was prepared to have a homogenous thickness within 1.5 mm. A horizontal mattress suture using 4-0 vicryl was utilized to secure the graft around the tooth at the level of the cementoenamel junction (CEJ). The flap was positioned over the graft, 2 mm coronal to the CEJ, and sutured with 6-0 polypropylene suture.

Postoperative Procedures

Following the surgical procedures, subjects were advised to use analgesics as needed for pain. Subjects were instructed to use postoperative sponges to gently clean the teeth at the surgical sites during the first 3 weeks postoperatively, and to brush the rest of the teeth as usual and rinse with 0.12% chlorhexidine gluconate twice daily for 2 weeks. The sutures were removed 14 days after the surgery.

Clinical Parameters

One investigator who was blinded to the group allocation was assigned to perform all measurements. The intra-examiner reliability of measurements was assessed in six subjects in two different sessions (Kappa coefficient = 0.75). The following variables were assessed at baseline (before the surgical procedures) and 1-year post-surgery: (1) probing depth (PD), the distance from the gingival margin to the depth of the gingival sulcus at the midbuccal aspect using a periodontal probe (12 UNC, HuFriedyGroup) and rounded to the nearest millimeter; (2) gingival recession (GR), the distance from the gingival margin to either the CEJ or its estimation in cases that presented a noncarious cervical lesion at the midbuccal aspect; (3) clinical attachment level (CAL), the sum of the PD and GR; (4) keratinized tissue width (KTW), the distance from the gingival margin to the mucogingival junction measured in millimeters at the midbuccal site; (5) gingival thickness (GT), measured as previously described²⁵ in millimeters at the attached gingiva or alveolar mucosa at the midbuccal site and 2 mm apical to the gingival margin using a #15 endodontic reamer with a silicon disk stop. The soft-tissue surface was pierced at a 90-degree angle with slight pressure until hard tissue was reached. The silicon stop on the reamer was moved until it was in close contact with the tissue. The distance between the tip of the reamer and the inner border of the silicon stop was measured using a caliper with 0.1-mm calibration; (6) recession reduction (RR), calculated by comparing GR at baseline to GR after 1 year; (7) percentage of root coverage (%RC), calculated by RR/GR at baseline x 100; (8) percentage of sites that gained complete root coverage (%CRC).

In addition to the clinical parameters, the following patient-centered outcomes were measured: (1) postoperative pain: patients reported the amount of pain during the first 7 days after the procedure using a visual analog scale (VAS); (2) satisfaction: patients were asked if they were satisfied with the overall results of the procedures, and this was recorded as part of the patients' reported outcome assessment.

Statistical Analysis

Descriptive statistics were expressed as mean ± SD, and normality was tested using the Shapiro-Wilk test. Inter- and intragroup comparisons for GR, PD, CAL, GT, KTW, RR, Pain, and Satisfaction were performed using either paired t-test when normal distribution was achieved or Wilcoxon test. The %CRC and %RC were analyzed by chi-square. A significance level of 5% was adopted.

Results

Thirty-six subjects, aged 23 to 75 years (mean: 58.41 ± 12.51 years), comprising 18 (50%) males and 18 (50%) females, were included in the study and followed-up for 1 year. A total of 72 teeth were evaluated (split-mouth study). Table 1 shows demographic data of the study subjects. There was no significant difference between the groups regarding the type of teeth included. Healing was uneventful in all cases, and no adverse events or complications were observed after the surgical procedures. Figure 1 through Figure 4 depict representative clinical cases of the two groups.

Clinical Parameter Outcomes

The mean GR measurements at baseline were 3.13 mm and 3.11 mm in the CAF + CTG and PST + CM groups, respectively (P = .9). After 1 year, both groups showed a significant decrease in GR (P < .001), and there was no significant difference between the groups (P = .4) (Table 2). The RR was 1.98 mm ± 0.74 mm for CAF + CTG, and 1.97 mm ± 1 mm for PST + CM (P = .53); the percentage of root coverage was 65.4% ± 24.6% and 63.6% ± 24.5%, respectively (P = .72). In addition, both groups presented similar percentage of CRC (Table 3). Both groups presented significant gain of attachment level, from 4.44 mm ± 0.84 mm to 2.95 mm ± 0.86 mm (P < .001) in the CAF + CTG group and from 4.44 mm ± 1 mm to 3.22 mm ± 1.15 mm in the PST + CM group (P < .001), with no significant difference between groups (P = .9).

Both groups presented a slight increase in GT: 0.32 mm ± 0.58 mm for the CAF + CTG group, and 0.12 mm ± 0.58 mm for PST + CM, with no significant difference between groups (P = .1), which was not enough to significantly improve the GT between baseline and the final evaluation in both groups. On the other hand, the CAF + CTG group presented a significant improvement in KTW after 1 year, from 2.38 mm ± 1.5 mm to 2.61 mm ± 1.07 mm (P = .002), which was not the case in the PST + CM group (Table 2). The final values of KTW, however, were similar for both groups: 2.61 mm ± 1.07 mm for CAF + CTG and 2.66 mm ± 1.24 mm for PST + CM (P = .48).

Patient-Centered Outcomes

The patient-centered parameters did not present statistically significant differences between groups. The level of postoperative pain was similar: 4.9 ± 3.10 for the CAF + CTG group and 3.84 ± 3.26 for the PST + CM group (P = .150). Similarly, satisfaction with the final results did not present statistically significant differences between groups: 7.15 ± 2.97 for the CAF + CTG group and 7.81 ± 3.01 for the PST + CM group (P = .277) (Table 4).

Discussion

The present study compared the outcomes of two different surgical techniques for the treatment of gingival recession defects: the pinhole surgical technique with the use of collagen membrane,¹⁹ and the coronally advanced flap technique with the use of connective tissue graft. The former does not use vertical releasing incisions,^19,26 and this may enhance wound healing and result in less postoperative pain and discomfort.¹⁹ The results of the present study did not show a significant advantage of one approach over the other. There were no significant differences between the two treatments for root coverage and recession reduction: %RC was 65.4% ± 24.6% and 63.6% ± 24.5% (P = .72), and RR was 1.98 mm ± 0.74 mm and 1.97 mm ± 1 mm (P = .53) for CAF + CTG and PST + CM, respectively. In addition, both procedures resulted in clinical attachment gain. It should be noted that this trial was designed as a superiority clinical trial. In order to evaluate if the two techniques are similar, an equivalence trial would need to be performed.

Few patients in the present sample showed complete root coverage following treatment (25% in the CAF + CTG group and 22% in the PST + CM group; P = .31). It has been suggested that a number of patient- and site-specific factors may influence the treatment outcome of recession defects, and more research is needed on this topic.²⁷ One factor that may have affected this result in this study is the inclusion of teeth with cervical lesions. Although the method described by Zucchelli et al was used to measure the actual amount of coverage achieved,²⁸ the presence of a noncarious cervical lesion may have affected the outcome and influenced the %CRC, %RC, and RR.^29-31 Another factor that may have influenced the amount of root coverage in this study is the initial GT values. Studies in the literature already pointed out that GT <0.8 mm may influence the attainability and stability of CRC.³² Hence, it seems that the selection of cases may have a paramount effect on the outcome of treatment of recession defects, and studies evaluating the efficacy of treatment should take this factor into consideration.

An interesting finding of the present study is the final result of GT and KTW. Both groups generated a slight gain of GT that did not show significant difference when intra- and intergroup comparisons were performed. It was expected that the CTG would provide significant gain for this parameter, but this was not observed in the study. It is possible that an inherent error in the method used to measure the thickness of the tissue contributed to the results. Despite the fact that the analog method has been used for many years, it is susceptible to errors. For more accurate values, digital measurements should be warranted in future studies.

Another possibility for the insignificant differences in GT between groups is the use of relatively thin CTG grafts in all cases in order to enhance esthetics. It has been shown that the greater the thickness of the CTG, the lesser the esthetic outcomes.³³ Consequently, the present authors used very thin CTG, which could have influenced the final GT outcome. Therefore, when planning, clinicians should attempt to achieve balance between esthetics and GT gain. Finally, a collagen membrane was used in the PST group. This material does not have the property to generate a substantial amount of tissue thickness gain. As a result, only minimal GT gain was observed in this group. Future studies using different material with the PST technique should be considered to enhance the GT gain. Additionally, only the CAF + CTG group showed a statistically significant increase in KTW.

Both treatment groups presented comparable levels of postoperative pain. The CAF + CTG method requires an additional surgical site, ie, the palatal donor area, which may increase postoperative morbidity.³⁴ However, depending on the surgical technique used to harvest the CTG, the postoperative pain can vary.³⁴ In this study, the authors used the technique described by Bruno, which involves preserving the epithelial layer on the donor area to protect the wound and minimize postoperative pain.²¹ This may have contributed to the statistically insignificant level in postoperative pain between the groups.³⁵ Also, the overall satisfaction with the treatments was not significantly different between the groups. The amount of defect coverage following treatment has been shown to be the most important factor influencing the patient's perception of the esthetic outcome.³⁶ This is consistent with this study's findings that the PST + CM and CAF + CTG techniques resulted in comparable amounts of root coverage and similar levels of patient satisfaction with the treatments.

A limitation of the present study is the relatively small sample size. A larger sample size is required to confirm these findings. In addition, future studies using digital measurements would provide more accurate submillimetric quantification of the soft-tissue changes than clinical measurement using a periodontal probe.

Conclusion

Within the limitations of the present study, it can be concluded that both CAF + CTG and PST + CM provide similar successful treatment for Miller class I and II (Cairo recession type 1) gingival recession defects.

Disclosure

Dr. Chao holds a registered trademark for the Pinhole Surgical Technique.

About the Authors

Othman Shibly, DDS, MS
Former Clinical Professor, Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo, Buffalo, New York

John C. Chao, DDS
Private Practice, Alhambra, California

Jasim M. Albandar, DMD, PhD
Professor, Department of Periodontology and Oral Implantology, Temple University School of Dentistry, Philadelphia, Pennsylvania; Private Practice, East Norriton, Pennsylvania

Nehal Almehmadi, BDS, MS
Private Practice, Periodontist, Richmond, Virginia

Mohanad Al-Sabbagh, DDS, MS
Professor and Chief, Division of Periodontology, Department of Oral Health Practice, University of Kentucky College of Dentistry, Lexington, Kentucky

References

1. Albandar JM, Kingman A. Gingival recession, gingival bleeding, and dental calculus in adults 30 years of age and older in the United States, 1988-1994. J Periodontol. 1999;70(1):30-43.

2. Romandini M, Soldini MC, Montero E, Sanz M. Epidemiology of mid-buccal gingival recessions in NHANES according to the 2018 World Workshop Classification System. J Clin Periodontol. 2020;47(10):1180-1190.

3. Mounssif I, Stefanini M, Mazzotti C, et al. Esthetic evaluation and patient-centered outcomes in root-coverage procedures. Periodontol 2000.2018;77(1):19-53.

4. Miller PD Jr. Root coverage using a free soft tissue autograft following citric acid application. Part 1: technique. Int J Periodontics Restorative Dent. 1982;2(1):65-70.

5. Holbrook T, Ochsenbein C. Complete coverage of the denuded root surface with a one-stage gingival graft. Int J Periodontics Restorative Dent.1983;3(3):8-27.

6. Langer B, Langer L. Subepithelial connective tissue graft technique for root coverage. J Periodontol. 1985;56(12):715-720.

7. Grupe HE, Warren RF Jr. Repair of gingival defects by a sliding flap operation. J Periodontol. 1956;27(2):92-95.

8. Pfeifer JS, Heller R. Histologic evaluation of full and partial thickness lateral repositioned flaps: a pilot study. J Periodontol.1971;42(6):331-333.

9. Bernimoulin JP, Luscher B, Muhlemann HR. Coronally repositioned periodontal flap. Clinical evaluation after one year. J Clin Periodontol.1975;2(1):1-13.

10. Tarnow DP. Semilunar coronally repositioned flap. J Clin Periodontol. 1986;13(3):182-185.

11. Allen EP, Miller PD Jr. Coronal positioning of existing gingiva: short term results in the treatment of shallow marginal tissue recession. J Periodontol.1989;60(6):316-319.

12. Sorrentino JM, Tarnow DP. The semilunar coronally repositioned flap combined with a frenectomy to obtain root coverage over the maxillary central incisors. J Periodontol. 2009;80(6):1013-1017.

13. Maynard JG Jr. Coronal positioning of a previously placed autogenous gingival graft. J Periodontol. 1977;48(3):151-155.

14. Gottlow J, Karring T, Nyman S. Guided tissue regeneration following treatment of recession-type defects in the monkey. J Periodontol. 1990;61(11):680-685.

15. Harris RJ. A comparative study of root coverage obtained with an acellular dermal matrix versus a connective tissue graft: results of 107 recession defects in 50 consecutively treated patients. Int J Periodontics Restorative Dent. 2000;20(1):51-59.

16. Modica F, Del Pizzo M, Roccuzzo M, Romagnoli R. Coronally advanced flap for the treatment of buccal gingival recessions with and without enamel matrix derivative. A split-mouth study. J Periodontol.2000;71(11):1693-1698.

17. Chambrone L, Chambrone D, Pustiglioni FE, et al. Can subepithelial connective tissue grafts be considered the gold standard procedure in the treatment of Miller Class I and II recession-type defects? J Dent. 2008;36(9):659-671.

18. Cairo F, Barootchi S, Tavelli L, et al. Aesthetic-and patient-related outcomes following root coverage procedures: a systematic review and network meta-analysis. J Clin Periodontol.2020;47(11):1403-1415.

19. Chao JC. A novel approach to root coverage: the pinhole surgical technique. Int J Periodontics Restorative Dent. 2012;32(5):521-531.

20. Miller PD Jr. A classification of marginal tissue recession. Int J Periodontics Restorative Dent. 1985;5(2):8-13.

21. Bruno JF. Connective tissue graft technique assuring wide root coverage. Int J Periodontics Restorative Dent. 1994;14(2):126-137.

22. Zucchelli G, Amore C, Sforza NM, et al. Bilaminar techniques for the treatment of recession-type defects. A comparative clinical study. J Clin Periodontol. 2003;30(10):862-870.

23. Nelson SW. The subpedicle connective tissue graft. A bilaminar reconstructive procedure for the coverage of denuded root surfaces. J Periodontol. 1987;58(2):95-102.

24. Harris RJ. The connective tissue and partial thickness double pedicle graft: a predictable method of obtaining root coverage. J Periodontol. 1992;63(5):477-486.

25. Santamaria MP, Rossato A, Miguel MMV, et al. Comparison of two types of xenogeneic matrices to treat single gingival recessions: a randomized clinical trial. J Periodontol. 2022;93(5):709-720.

26. Allen AL. Use of the supraperiosteal envelope in soft tissue grafting for root coverage. I. rationale and technique. Int J Periodontics Restorative Dent. 1994;14(3):216-227.

27. Chambrone L, Tatakis DN. Periodontal soft tissue root coverage procedures: a systematic review from the AAP Regeneration Workshop. J Periodontol. 2015;86(2 suppl):S8-S51.

28. Zucchelli G, Mele M, Checchi L. The papilla amplification flap for the treatment of a localized periodontal defect associated with a palatal groove. J Periodontol. 2006;77(10):1788-1796.

29. Pini Prato G, Di Gianfilippo R, Pannuti CM, et al. Diagnostic reproducibility of the 2018 Classification of Gingival Recession Defects and Gingival Phenotype: a multicenter inter- and intra-examiner agreement study. J Periodontol. 2023;94(5):661-672.

30. Santamaria MP, Mathias-Santamaria IF, Ferraz LFF, et al. Rethinking the decision-making process to treat gingival recession associated with non-carious cervical lesions. Braz Oral Res. 2021;35(suppl 2):e096.

31. Mathias-Santamaria IF, Silveira CA, Rossato A, et al. Single gingival recession associated with non-carious cervical lesion treated by partial restoration and coronally advanced flap with or without xenogenous collagen matrix: a randomized clinical trial evaluating the coverage procedures and restorative protocol. J Periodontol.2022;93(4):504-514.

32. Baldi C, Pini-Prato G, Pagliaro U, et al. Coronally advanced flap procedure for root coverage. Is flap thickness a relevant predictor to achieve root coverage? A 19-case series. J Periodontol.1999;70(9):1077-1084.

33. Cairo F, Cortellini P, Nieri M, et al. Coronally advanced flap and composite restoration of the enamel with or without connective tissue graft for the treatment of single maxillary gingival recession with non-carious cervical lesion. A randomized controlled clinical trial. J Clin Periodontol.2020;47(3):362-371.

34. Zucchelli G, Mele M, Stefanini M, et al. Patient morbidity and root coverage outcome after subepithelial connective tissue and de-epithelialized grafts: a comparative randomized-controlled clinical trial. J Clin Periodontol. 2010;37(8):728-738.

35. Miguel MMV, Mathias-Santamaria IF, Rossato A, et al. Microcurrent electrotherapy improves palatal wound healing: randomized clinical trial. J Periodontol. 2021;92(2):244-253.

36. Cairo F, Rotundo R, Miller PD, Pini Prato GP. Root coverage esthetic score: a system to evaluate the esthetic outcome of the treatment of gingival recession through evaluation of clinical cases. J Periodontol. 2009;80(4):705-710.