Evaluation of the Association Between Keratinized Mucosa and Peri-implant Tissue HealthBackground:

The importance of keratinized mucosa on peri-implant tissue health is unclear. Although it has been suggested that insufficient keratinized mucosa affects peri-implant health, some argue otherwise. However, it has been shown that patients have difficulty maintaining oral hygiene in the presence of insufficient keratinized tissue. For this purpose, the free gingival graft is recommended. There is scarce data examining the effect of free gingival graft on peri-implant health.

Aim/Hypothesis :

This 4-year prospective clinical study aimed to evaluate the importance of keratinized mucosa and to investigate the effect of free gingival graft procedure on peri-implant tissue health.

Material and Methods :

Patients who received maintenance treatment immediately after implant-supported fixed prosthesis placement in the mandible were included in this study. After prosthesis delivery, the patients were allocated into three groups, based on the width of keratinized mucosa (KM) and patients consent on the free gingival graft procedure: KMS (KM ≥2 mm), KMD (KM <2 mm), and FGG (KM <2 mm initially and having surgically increased keratinized mucosa). A maintenance program was administered to the subjects at 6 months, 1, 2, 3, and 4 years. In these sessions, prophylaxis and oral hygiene instructions were applied. Modified plaque index (mPI), probing depth (PD), modified bleeding index (mBI), KM, and marginal bone loss (MBL) were assessed at the baseline and 4 years follow-up period. Three groups were compared in terms of clinical and radiographic parameters.

Results:

The analysis was conducted with 35 patients (22 female, 13 male) with a mean age of 49.11±9.03 years. Twelve patients belonged to the KMS group, 12 patients to the KMD, and the remaining 11 patients to the FGG group. When baseline and 4-year evaluations were analyzed within the groups, mPI and MBL did not change in any of the groups between the follow-up periods. PD value increased significantly in KMS and FGG groups (p= 0.00, p= 0.00, respectively) and mBI only in the KMS group (p= 0.04). KM showed a significant increase in the KMD group between the periods (p= 0.01). At baseline, there was significant difference between the groups in terms of KM, and MBL (p= 0.00, p= 0.01, respectively). KMD displayed significantly greater MBL value than the other groups. However, there was a significant difference only in KM between the groups at 4-year follow-up (p= 0.02). mPI, PD, mBI, and MBL did not differ between the groups at the final follow-up.

Conclusion and Clinical implications :

This clinical study revealed that clinical and radiographic parameters did not differ according to the amount of keratinized mucosa, and the free gingival graft did not provide an additional benefit on peri-implant health. This result can be attributed to the compliance of the patients to the maintenance sessions and it can be concluded that keratinized mucosa does not affect peri-implant health in compliant patients. However, there is a need for future studies with larger samples.

Keywords: Clinical studies/trials, Dental implants, Peri-implantitis