A Commentary on

Mahardawi B, Jiaranuchart S, Damrongsirirat N et al.

The lack of keratinized mucosa as a risk factor for peri-implantitis: a systematic review and meta-analysis. Sci Rep 2023; 13: 3778.

GRADE Rating:


Dental implants are widely used to replace missing teeth and restore oral function and aesthetics1,2. However, complications such as peri-implant mucositis and peri-implantitis can arise, posing risks to implant success3,4. Peri-implant mucositis involves inflammation without bone loss, while peri-implantitis entails progressive bone loss and mucosal inflammation5. These conditions can significantly impact peri-implant tissue health and compromise implant longevity3. Preventive measures and early risk assessment are crucial for managing peri-implant inflammations6,7 .Among various risk factors, the width of keratinized mucosa (KM) has been suggested as a potential indicator of peri-implantitis8,9. Studies have reported conflicting findings regarding the association between KM and peri-implantitis prevalence10,11,12, making it an area requiring further investigation. The reviewed meta-analysis by Mahardawi et al. aimed to analyze the available evidence and determine whether the absence of KM increased the risk of peri-implantitis. The synthesis also considered specific case definitions, restorative protocols, and maintenance conditions to mitigate potential confounding factors. In other words, the study intended to contribute to improving implant outcomes and patient care by clarifying the relationship between KM and peri-implantitis.

The review effectively addressed the research question, examining the impact of the absence of KM on the risk of peri-implantitis while considering relevant confounding factors. A thorough literature search identified 22 relevant articles, with 16 cross-sectional studies included in the meta-analysis. The overall analysis revealed a significant association between the lack of KM and a higher prevalence of peri-implantitis. Subgroup analyses consistently supported this finding, including case definition, fixed prostheses, regular maintenance, and adjustment for other variables. The quality assessment of the included studies indicated moderate to high quality. Although there might be some publication bias, the results overall suggest that the absence of KM is a risk factor that increases the prevalence of peri-implantitis. It is essential to consider this factor when placing dental implants. However, the review did not explicitly discuss the applicability of the findings or elaborate on potential biases in the review process. Moreover, a recent review and meta-analysis by Ravidà et al. 13. did not find a significant difference in peri-implant disease outcomes between sites with less than 2 mm or greater than or equal to 2 mm of KM width.

This systematic review possesses several notable strengths. Firstly, it includes a substantial number of studies, enhancing the reliability and robustness of the findings. Additionally, the review conducted multiple meta-analyses based on specific study features, such as case definition, prosthesis type, and maintenance frequency, thereby minimizing the impact of potential confounding factors and increasing the homogeneity of the results. Moreover, the review avoids fixating on a specific cut-off point for KM and instead considers various values, acknowledging the arbitrary nature of determining an optimal width.

Several limitations should be acknowledged. The predominant inclusion of cross-sectional studies limits the establishment of causality and may introduce bias. Thus, future longitudinal studies would provide more robust evidence in this regard. Furthermore, due to insufficient data, the review could not account for certain patient-related and site-specific factors, such as implant location, oral hygiene, time-in-function, and bone augmentation. The reliance on cross-sectional designs also introduces the possibility of deviation in outcomes based on the enrolled sample, potentially reducing the quality of evidence. Finally, although sensitivity analysis did not indicate significant changes, there is a slight asymmetry in the funnel plot, suggesting the presence of publication bias that should be considered when interpreting the results.

Future research on peri-implantitis should focus on longitudinal studies with standardized case definitions and analysis methods to establish stronger causal relationships. Additionally, exploring the impact of patient-related and site-specific factors, such as implant location, oral hygiene practices, time-in-function, and the influence of bone augmentation, will provide a more comprehensive understanding of peri-implantitis risk factors. Determining optimal cutoff points for KM width and its association with peri-implant tissue health could inform improved clinical practices in dental implantology.

To sum up, the lack of KM increased the risk of peri-implantitis. The review used a rigorous study selection process, data extraction, and quality assessment but could have addressed applicability and potential biases more explicitly. Additionally, the review did not reach high-quality evidence due to insufficient data on patient-specific factors and the predominance of cross-sectional studies. Future research should confirm these findings and identify additional risk indicators.