Rotary Versus Manual Degranulation in Alveolar Ridge Preservation

Tooth extraction is one of the most common procedures in dental practice, initiating a complex healing process within the socket. A critical step for uneventful healing is the complete removal of chronic granulation tissue, which is often present because of pre-existing periapical or periodontal pathology. Retained granulation tissue can impede bone regeneration and contribute to postoperative complications.

1.1 Study Design: A prospective, single-center, parallel-group randomized controlled trial with 1:1 allocation, conducted and reported in accordance with the CONSORT 2025 statement.

This study introduces an objective endpoint to this comparison by utilizing Toluidine Blue (TB), a vital stain that selectively binds to acidic tissue components like DNA and RNA, which are abundant in dysplastic and highly cellular tissues like granulation tissue. By applying TB to the socket immediately after extraction and continuing debridement until no residual stain remains, this study replaces the surgeon's subjective assessment of a clean socket with a visual endpoint, alongside cone-beam computed tomography (CBCT) ridge dimension changes.

Furthermore, the rationale for thorough degranulation extends beyond facilitating uneventful healing and is a critical determinant for the success of subsequent restorative procedures, particularly alveolar ridge preservation (ARP) and dental implant placement. Retained chronic granulation tissue can act as a physical and biological barrier, impeding the migration and proliferation of osteogenic cells and the integration of bone graft materials. This compromised graft incorporation can lead to suboptimal bone quality and volume, ultimately undermining the primary goal of ARP to minimize post-extraction ridge atrophy. Moreover, the presence of inflamed, non-mineralized tissue at the future implant site has been linked to higher failure rates, as it prevents the direct bone-to-implant contact osseointegration essential for long-term stability. Therefore, establishing a clean, well-prepared bony socket is not merely a procedural step, but a fundamental prerequisite to creating a predictable environment for successful bone grafting and, ultimately, the placement of a functional dental implant. While ARP studies focus on grafting materials and membranes, little attention has been given to the effect of degranulation technique itself.

Rationale:

Although alveolar ridge preservation (ARP) procedures have been widely investigated with a focus on grafting materials and membrane types, the influence of the degranulation technique, a critical preliminary step in socket healing, has received little scientific attention. Incomplete removal of inflamed or necrotic granulation tissue may hinder bone regeneration, compromise graft integration, and increase the risk of postoperative complications. Conversely, achieving a clean, viable bony socket can enhance the healing environment and improve both soft and hard tissue outcomes. This study proposes that the method of degranulation, whether manual or rotary, may significantly influence healing outcomes by affecting the thoroughness of socket cleaning, operative time, and the subsequent bone preservation process. The use of Toluidine Blue (TB) staining provides an objective and reproducible endpoint for assessing socket cleanliness, while CBCT-based measurement of alveolar ridge dimensions enables quantitative evaluation of bone healing.

Hypothesis:

It is hypothesized that rotary degranulation using mechanical burs will result in more efficient and complete removal of granulation tissue, as evidenced by shorter operative times, higher rates of TB-confirmed clean sockets, and improved clinical and radiographic healing outcomes including alveolar ridge preservation when compared with traditional manual curettage.

1.2 Groups: Intervention Group (n = 31 sites): Granulation tissue removed with a 2.5 mm super-coarse diamond degranulation bur.

Control Group (n = 29 sites): Granulation tissue removed with a #85 Lucas surgical curette, 2.5 mm.

Sample size: calculated in G*Power 3.1.9.7 for a two-tailed independent-samples t test. A large effect size (Cohen's d = 1.0) was assumed a priori, as no previous randomized comparison of socket degranulation techniques was available from which to derive an effect estimate. With alpha 0.05 and 95% power, 54 extraction sites (27 per group) were required. Recruitment was targeted at 58-60 sites to allow for loss to follow-up, and 60 were enrolled.

Standardized Procedure: A single surgeon performed all procedures using 2.5x loupes and a shadowless headlight to ensure a consistent endpoint.

Pre-operative Volumetric Assessment: Pre-operative volumetric assessment of the roots within alveolar bone and the periapical lesion was performed using CBCT, a validated tool for such diagnostics, and calculated using ITK-SNAP software. The resulting combined root-and-lesion volume in cubic millimeters (mm³) provides a standardized baseline measure of initial pathology burden and is used as a covariate in the analysis of the primary outcome.

Cone-beam computed tomographic images were acquired on a Planmeca Viso G7 unit (Planmeca Oy, Helsinki, Finland) using a 10 x 10 cm volume, at 90 kV and 8 mA with an exposure time of 13.67 s, at an isotropic voxel size of 400 microns, using the standard exposure protocol with Planmeca CALM movement correction enabled. Images were exported in DICOM format and analyzed in CS 3D Imaging v3.10.21 (Carestream Dental LLC, Atlanta, GA, USA).

Intervention Protocol:

2.1 Tooth Extraction: Atraumatic flapless extraction was performed for all teeth. The periodontal ligament was severed with periotomes, the tooth was luxated with elevators and delivered with forceps, and tooth sectioning was used where required to avoid bone removal. Although the protocol permitted minimal flap reflection where access required it, no flap was elevated at any site.

2.2 Randomization: Allocation was applied at the level of the extraction site. A separate sequentially numbered, opaque, sealed envelope was opened for each site after the tooth had been extracted. The allocation sequence was computer-generated in a 1:1 ratio using block randomization with randomly varying block sizes (Sealed Envelope Ltd). Patients contributing more than one site could therefore receive both techniques, at separate appointments.

2.3 Staining Phase: To provide an objective endpoint, the socket was stained with 1% Toluidine Blue, a vital stain that binds to tissues with high cellular turnover, such as granulation tissue. An intra-oral digital photograph was taken immediately after the extraction.

The extraction socket was irrigated with saline for 20 seconds.

1% Toluidine Blue was applied to the socket walls and the granulation tissue with a micro-brush for 1 minute.

The socket was rinsed with saline for 1 minute to remove excess stain.

2.4 Degranulation Phase:

Intra-oral digital photographs were taken immediately after the socket staining. A digital stopwatch (HS-3V-1R, Casio Computer Co., Tokyo, Japan), operated by the second assistant, was started when the instrument first engaged the socket. Times were recorded to the nearest second.

Test Group: Degranulation was performed using a 2.5 mm round super-coarse diamond degranulation bur (ISO 801LD.RAXL.025) at 1,000 revolutions per minute (RPM) at the bur, mounted in a 1:1 contra-angle surgical handpiece (WS-56 L G, W\&H Dentalwerk Bürmoos GmbH, Bürmoos, Austria) driven by a surgical motor (Implant 900, Dentsply Sirona, Bensheim, Germany).

Control Group: Degranulation was performed using a #85 Lucas surgical curette, 2.5 mm.

The timer was stopped when the surgeon declared the socket free of soft tissue and free of residual Toluidine Blue staining. This was recorded as the primary outcome (time in seconds). An intra-oral digital photograph was taken immediately after degranulation.

Sterile 0.9% saline irrigation was maintained continuously throughout instrumentation in both groups: delivered to the bur head through an external irrigation line by the surgical motor's pump, with the console flow rate set to 100 mL/min, in the rotary group; and by an assistant using a 20 mL syringe with continuous suction in the manual group.

2.5 Alveolar Ridge Preservation Phase: Following debridement, all sockets underwent standardized alveolar ridge preservation with a mineralized particulate allograft (Puros Allograft, Zimmer Biomet Dental, Palm Beach Gardens, FL, USA) covered by a resorbable collagen membrane (BioMend, Zimmer Biomet Dental, Palm Beach Gardens, FL, USA). No flap was elevated and primary closure was not attempted. Because coronal flap advancement would have required releasing incisions and displacement of the mucogingival junction, all sites were left to heal by secondary intention with the collagen membrane intentionally exposed and stabilized with a hidden X suture (5-0 PTFE, Medipac - Th. Kazantzidis S.A., Kilkis, Greece). This approach was identical in both groups. An intra-oral digital photograph was taken after grafting and suturing.

Post-operative Care: All patients received standardized postoperative instructions.

All patients received amoxicillin 500 mg three times daily for 7 days, and ibuprofen 600 mg three times daily for the first 3 postoperative days and thereafter as needed, to a maximum of 10 days. The same regimen was prescribed for every patient in both groups.

3.1 Outcome Measure: Primary: Operation Time The operator and the assistant recording operative time could not be blinded, as the two instruments are visually and audibly distinct. All cone-beam computed tomographic measurements contributing to the analysis are performed by one examiner who is blinded to treatment allocation and who takes no part in the surgical procedures. A second examiner, also blinded to allocation and not involved in the surgical procedures, independently measures a predefined subset of scans for reliability assessment only. The primary outcome of operative time was selected as a key metric of clinical efficiency.

The second assistant recorded the time in seconds from instrument engagement until the surgeon declared the socket clinically stain-free and free of any soft tissue.

Secondary:

Toluidine Blue "stain-free" endpoint (not assessed as an independent endpoint; see Statistical Analysis).

CBCT-measured ridge changes at 3 and 6 months

Patient-reported outcome measures (pain and facial swelling, each on a 0-10 visual analog scale [VAS])

Postoperative complications (infection, delayed healing, premature membrane loss, graft loss)

Statistical Analysis:

All analyses were two-sided with α = 0.05 and 95% confidence intervals (CIs). The primary outcome (operative time in seconds) was compared between the rotary-bur and manual-curette groups using analysis of covariance (ANCOVA) with pre-operative CBCT lesion volume (mm³) entered as a covariate to increase precision and adjust for baseline pathology burden. Model assumptions (linearity of covariate effect, homoscedasticity, normality of residuals) were evaluated by residual diagnostics. Because the residuals departed from normality, the pre-specified rank-ANCOVA sensitivity analysis was performed.

Post hoc sensitivity analyses of the radiographic outcomes are planned and will be identified as post hoc: one excluding both sites of the single adjacent same-quadrant pair in thesample, since adjacent sites share interseptal bone and their dimensional changes are not independent; and one excluding maxillary posterior sites, since post-extraction sinus pneumatization may affect the stability of the sinus floor as an apical reference landmark. Both sites of the adjacent pair are retained in the primary analyses.

Secondary outcomes:

Stain-free socket after a single debridement cycle was not assessed as an independent endpoint, because absence of residual Toluidine Blue staining served as the stopping rule for debridement rather than as a separate measurement. The planned logistic regression was therefore not performed. CBCT ridge dimensional changes (e.g., vertical/horizontal bone change) at follow-up: analyzed with a linear mixed-effects model (time as a within-subject factor, group as a between-subject factor, group × time interaction). Baseline dimension entered as a covariate. A patient-level random intercept is included to account for patients contributing more than one extraction site, and a site-level random intercept for repeated measurements of the same site over time. Patient-reported pain and facial swelling (VAS) at post-op days 1-7: assessed using a linear mixed-effects model.

Early complications (e.g., infection, delayed healing): compared with chi-square or Fisher's exact test; if timing is recorded, time-to-event curves (Kaplan-Meier) with a log-rank test will be added exploratorily. If no events occur, complications will be reported descriptively.

Where applicable, we will report effect sizes (mean difference, adjusted mean difference, odds ratio, or standardized effects) with 95% CIs. Analyses will follow intention-to-treat (ITT) principles; a per-protocol analysis excluding major protocol deviations will be provided as sensitivity. Missing outcome data will be minimized through follow-up; if >5% is missing, multiple imputations by chained equations will be used under a missing-at-random assumption. Because allocation was applied per extraction site and some patients contributed more than one site, patient-level clustering was addressed by refitting the primary model with cluster-robust standard errors and, separately, as a linear mixed-effects model with a patient-level random intercept, from which the intraclass correlation coefficient was derived. Statistical analyses were performed using IBM SPSS Statistics, version 31.0.2.0 (IBM Corp., Armonk, NY, USA).