Tuberosity vs. Palate: Comparing Donor Sites for Periodontal Soft Tissue Grafting

Exploring the Optimal Donor Sites: Is Palate or Tuberosity Superior?

The debate over optimal donor sites for soft tissue grafting in periodontal plastic surgery continues to evolve, with emerging evidence suggesting potential advantages for tuberosity-derived grafts compared to the traditionally favored palatal donor sites. A recent systematic review has examined the clinical outcomes and patient experiences associated with these two primary intraoral donor sites, revealing intriguing differences in post-operative morbidity and tissue characteristics that may influence clinical decision-making.

Soft tissue augmentation procedures have seen steadily increasing demand in periodontal practice, with autogenous connective tissue grafts (CTGs) remaining the gold standard for root coverage procedures. While the hard palate has traditionally served as the primary harvest site, the maxillary tuberosity represents an alternative that may offer distinct advantages. This comprehensive review sought to evaluate tissue quality outcomes and patient-reported experiences following grafts harvested from these two intraoral donor locations, specifically focusing on procedures performed around natural teeth.

How Did Researchers Design the Study?

Following PRISMA guidelines, researchers conducted an extensive search across multiple databases (PubMed, Web of Science, OVID Medline, and Scopus) for studies published through December 2023. After screening 1,209 initial records, 13 studies met the inclusion criteria: seven randomized clinical trials, one clinical study, three prospective clinical studies, one observational study, and one split-mouth clinical study. The methodological quality assessment using the Revised Cochrane Risk of Bias tools (ROB-2 for RCTs and ROBINS-I for non-randomized studies) revealed generally favorable quality across most included studies, with only minor concerns identified in some domains.

Clinical Outcomes and Tissue Quality: What Are the Differences?

Notably, only one study (Amin et al.) directly compared tuberosity and palatal donor sites within the same investigation, representing a significant limitation in the available comparative evidence. This split-mouth clinical study found that tuberosity-derived grafts demonstrated superior post-operative outcomes in several key dimensions. Patients experienced significantly lower pain levels at tuberosity donor sites compared to palatal sites during the first two postoperative weeks (mean pain scores of 2.6 versus 5.9 on a 10-point scale, respectively). The researchers attributed this difference to the anatomical characteristics of the tuberosity region, which experiences less friction during mastication and speaking, and maintains a thicker layer of connective tissue overlying the bone compared to the palate.

From a tissue quality perspective, the healed graft thickness at 8 weeks post-operatively was greater for tuberosity grafts in both free gingival graft (FGG) and connective tissue graft (CTG) groups. Mean gingival thickness measurements were 2.9 ± 0.5 mm and 2.7 ± 0.7 mm for tuberosity FGG and CTG groups respectively, compared to 2.3 ± 0.6 mm and 2.1 ± 0.7 mm for palatal grafts. This suggests that tuberosity grafts may offer superior dimensional stability, potentially due to differences in tissue composition. The tuberosity area primarily consists of dense collagen fibers with minimal fatty or glandular components, covered by a well-keratinized but relatively thin epithelial layer compared to palatal tissue. Interestingly, no significant difference was observed in the mean percentage of root coverage between the two donor sites (67 ± 12% for tuberosity versus 62 ± 13% for palate, p = 0.102).

Could Harvesting Techniques Influence Patient Comfort?

Beyond donor site comparisons, the review highlighted variations in harvesting techniques for palatal grafts that impact clinical outcomes and patient comfort. Harris found that the parallel incisions method resulted in less postoperative discomfort, smaller wounds at one week, more uniform grafts, and greater ease of clinical application compared to the free gingival graft knife method. Similarly, Langer and Langer's trap door approach showed advantages over the Unigraft knife technique, with faster healing and potentially reduced patient discomfort, though both achieved comparable root coverage outcomes. These findings emphasize that technique selection represents another important variable in optimizing patient experience, regardless of donor site.

Are Autogenous Grafts Still the Gold Standard?

Several studies also compared autogenous grafts with tissue substitutes such as acellular dermal matrix (ADM) and collagen matrix (CM). While these alternatives generally resulted in reduced surgical time and patient morbidity, autogenous CTGs typically demonstrated superior clinical outcomes in terms of keratinized tissue width (KTW) enhancement and gingival thickness increase. This suggests that despite the advantages of alternative materials, autogenous tissue continues to offer benefits that may justify the additional donor site morbidity in specific clinical scenarios.

How Do Vascular Considerations Impact Donor Site Selection?

The blood supply considerations also play a crucial role in donor site selection. The greater palatine artery (GPA) supplies most of the hard palate, originating from the greater palatine foramen between the second and third maxillary molars. Its location varies with palatal vault height—approximately 17 mm from the gingival margin in high vaults, 12 mm in medium vaults, and just 7 mm in low vaults. For the tuberosity region, smaller branches from the GPA and lesser palatal artery provide nourishment. The reduced size and density of these vessels in the tuberosity area may explain the extended revascularization process and occasional necrosis observed in tuberosity grafts. These anatomical variations must be considered during surgical planning to minimize complications and optimize healing.

What Methodological Challenges Confront Systematic Reviews?

The systematic review faced several methodological challenges that prevented meta-analysis of the findings. Significant heterogeneity existed across studies in terms of outcome measures, timepoints, and reporting formats. For example, gingival thickness was assessed using various tools (periodontal probes, ultrasound, or calipers) and reported differently across studies. Follow-up durations ranged widely from 14 days to 3 years, making direct comparisons problematic. Additionally, pain assessment utilized different scales and evaluation timepoints, further complicating quantitative synthesis.

Can Histology Shed Light on Graft Performance?

Histological considerations further differentiate these donor sites. Bakhishov et al. found that de-epithelialized gingival grafts (DGG) exhibited partial epithelial remnants within superficial strata, while subepithelial connective tissue grafts (SCTG) demonstrated higher cellularity. These tissue composition differences may influence graft integration and long-term stability. Similarly, Azar et al. reported that SCTGs collected by mucosal technique possessed higher proportions of connective tissue proper and lower adipose tissue content compared to mucoperiosteal technique, while vascular tissue remained consistent. These histological variations could explain differences in clinical performance between grafts from different donor sites and harvesting techniques.

What Are the Study’s Limitations?

The authors acknowledge several limitations to their review, including its retrospective registration in PROSPERO after screening initiation, the limited number of high-quality comparative studies, and inconsistent reporting of key clinical variables across studies. Most significantly, the fact that only one study directly compared tuberosity and palatal donor sites limits the strength of conclusions regarding their relative advantages. This study's short follow-up period (8 weeks) and single-center design further constrain the generalizability of its findings.

Which Questions Remain Unanswered?

Looking forward, the authors emphasize the need for well-designed randomized controlled trials with standardized methodologies, comprehensive outcome reporting, and extended follow-up periods. Future research should prioritize patient-centered metrics, including discomfort, esthetic satisfaction, color matching, and functional outcomes to support evidence-based and individualized donor site selection. Given the current evidence limitations, clinicians should consider multiple factors when selecting donor sites, including the specific clinical scenario, patient anatomy, and potential for post-operative discomfort.

What Does the Evidence Suggest About Donor Sites?

In conclusion, while the hard palate remains a well-established and reliable source for soft tissue grafts, emerging evidence suggests that the tuberosity may offer advantages in terms of reduced post-operative pain and potentially superior dimensional stability. However, the limited comparative evidence available prevents definitive conclusions regarding the superiority of one donor site over the other. This review highlights a significant knowledge gap and underscores the need for further high-quality research to guide optimal donor site selection in periodontal plastic surgery.

Future Directions: How Might These Findings Influence Clinical Practice?

Could the histological differences between palatal and tuberosity tissues influence long-term graft stability and integration in ways not captured by short-term clinical studies? How might clinicians best incorporate both patient preference and anatomical considerations when selecting donor sites for soft tissue grafting procedures? As research continues to evolve in this area, what standardized outcome measures would most meaningfully capture both the clinical and patient-centered aspects of graft performance to facilitate better comparative analysis in future studies?

Summary

This systematic review examines clinical outcomes and patient experiences associated with two primary intraoral donor sites for soft tissue grafting in periodontal plastic surgery: the palatal region and the maxillary tuberosity. After screening 1,209 records, researchers identified 13 studies meeting inclusion criteria, though only one directly compared both donor sites. The evidence suggests that tuberosity-derived grafts may offer distinct advantages over traditional palatal grafts, particularly regarding post-operative patient comfort and tissue characteristics. In the comparative study by Amin et al., patients experienced significantly lower pain levels at tuberosity donor sites during the first two postoperative weeks compared to palatal sites, with mean pain scores of 2.6 versus 5.9 on a 10-point scale. Additionally, tuberosity grafts demonstrated superior healed graft thickness at 8 weeks post-operatively, with measurements ranging from 2.7 to 2.9 mm compared to 2.1 to 2.3 mm for palatal grafts. These differences are attributed to anatomical characteristics, including the tuberosity region's thicker connective tissue layer, reduced friction during mastication and speaking, and tissue composition consisting primarily of dense collagen fibers with minimal fatty or glandular components. However, no significant difference was observed in root coverage outcomes between the two donor sites. The review also highlights that harvesting technique selection influences patient comfort and clinical outcomes, with methods such as parallel incisions and trap door approaches showing advantages over traditional techniques. While autogenous connective tissue grafts remain the gold standard compared to tissue substitutes, the limited comparative evidence and methodological heterogeneity across studies prevent definitive conclusions about donor site superiority. The authors emphasize the need for well-designed randomized controlled trials with standardized methodologies, comprehensive outcome reporting, and extended follow-up periods to guide evidence-based donor site selection in clinical practice.