The lack of keratinized mucosa as a risk factor for peri-implantitis: a systematic review and meta-analysis

Risk factors for Peri-implantitis: An umbrella review of meta-analyses of observational studies and assessment of biases

OBJECTIVES

To perform a comprehensive quantitative and qualitative analysis of the findings from previously published meta-analyses and to assess existing biases.

DATA/SOURCES

A search was conducted for meta-analyses of observational studies investigating the association between any risk factor and peri‑implantitis in PubMed, Scopus, Cochrane Database of Systematic Reviews, and Epistemonikos, from inception until October 2023 (PROSPERO: CRD42024512408).

STUDY SELECTION

From a total of 5002 publications, 51 full-text articles were evaluated for eligibility, and 12 articles that described 41 unique meta-analyses evaluating the association between risk factors and periimplantitis were selected. Among 41 associations, 24 associations were significant. None of the associations were graded as convincing evidence. Two associations, presence of periodontitis (OR = 3.84 [95 % CI 2.58,5.72]) and cigarette smoking (RR=2.07 [95 % CI 1.41,3.04]) were graded as highly suggestive. Eight associations, diabetes mellitus, hyperglycaemia, lack of prophylaxis, history of chronic periodontal disease, ongoing or history of periodontal disease, implants located in the anterior region of the jaw (maxillary and mandibular), osteoprotegerin (OPG) gene polymorphisms, and lack of keratinized mucosal width were graded as suggestive evidence.

CONCLUSIONS

Periodontitis and cigarette smoking are highly suggestive risk factors for peri‑implantitis. The remaining risk factors which are suggestive require more high-quality studies to be performed to upgrade the level of evidence.

CLINICAL SIGNIFICANCE

The highly suggestive and suggestive risk factors for peri‑implantitis summarized in this umbrella review should be rigorously assessed, monitored and managed by clinicians to reduce the risk peri‑implantitis, as well as to form part of the preoperative consent process.

The Significance of Keratinized Mucosa in Implant Therapy: Narrative Literature Review and Case Report Presentation

Background/Objectives: Implant treatment in patients who require teeth extraction due to periodontitis presents a significant challenge. The consideration of peri-implantitis is crucial when planning the placement of dental implants. The predictability of implant treatment relies on the suitability of both hard and soft tissue quality. The aim of this article is to present a case report demonstrating a secure treatment protocol for implant procedures in patients with periodontitis requiring the extraction of all teeth, soft tissue management targeted at increasing the keratinized mucosa zone, and the provision of a reliable prosthetic solution. The secondary objective is to review the relevant literature regarding the significance of keratinized mucosa surrounding dental implants and its association with the occurrence of peri-implantitis. Case presentation: A 65-year-old female with generalized periodontitis, stage IV grade C and very poor oral hygiene came for treatment and rehabilitation of the lower jaw. CBCT revealed periodontal lesions and labio-lingual ridge dimensions in the region of teeth 34-44 from 8.0 to 10.2 mm. The first surgery included teeth extraction and periodontal lesions enucleation with simultaneous placement of four implants in the positions of teeth 32, 34, 42, 44. The second-stage surgery involved increasing the keratinized mucosa using two free gingival grafts. Conclusions: The present case report described the treatment process of the patient with periodontitis, including immediate implantation in the infected region, soft tissue augmentation using free gingival grafts and the ultimate placement of a bar-retained overdenture for final restoration. After two years of observation, despite questionable hygiene, no symptoms of gingival inflammation were detected. Furthermore, there is limited information in the literature regarding the correlation between inadequate keratinized gingiva and the occurrence of peri-implantitis.

The clinical efficacy of the allogenic demineralized dentin matrix graft for implant placement: a systematic review

PURPOSE

The Allogenic Demineralized Dentin Matrix (Allo-DDM) has been introduced as a new grafting material, and several investigations were conducted, showing its efficacy in bone augmentation. The objective of this systematic review was to evaluate the available literature on the Allo-DDM, revealing its clinical performance when used for implant placement procedures.

METHODS

This study is registered in the PROSPERO database (number: CRD42021264885, date: 30/7/2021). Four databases, as well as the grey literature, were searched, selecting human studies where the Allo-DDM was applied to augment implant-recipient sites.

RESULTS

Six articles were included. The total number of implants placed in Allo-DDM-grafted sites was 149. Mean implant stability quotient values (ISQ) were 60.4 and 68.67 for the primary and secondary ISQ, respectively (data from one study). Buccal marginal bone loss around implants was approximately 1.46 mm after 24 months of prosthetic loading (data from one study). Two studies documented a total of 6 cases of dehiscence of the grated area, however, not affecting early implant success. Histological findings from all studies showed new bone formation around the graft particles.

CONCLUSION

A low number of publications are available, presenting only preliminary results, thus the long-term success/survival of implants still needs to be further explored. Moreover, the possibility of bony dehiscence with the use of this material should be investigated. Within these limitations, the Allo-DDM could be a possible alternative to other grafting materials used for bone augmentation and implant placement. Nevertheless, considering this limited evidence, future studies are necessary to confirm this conclusion.

Augmentation of keratinized tissue using autogenous soft-tissue grafts and collagen-based soft-tissue substitutes at teeth and dental implants: Histological findings in a pilot pre-clinical study

AIM

To histomorphometrically assess three treatment modalities for gaining keratinized tissue (KT) at teeth and at dental implants.

MATERIALS AND METHODS

In five dogs, the distal roots of the mandibular second, third and fourth premolars were extracted. Dental implants were placed at the distal root areas 2 months later. After another 2 months, KT augmentation was performed at both distal (implants) and at mesial root (teeth) areas in the presence (wKT groups) or absence (w/oKT groups) of a KT band at the mucosal/gingival level. Three treatment modalities were applied randomly: apically positioned flap only (APF), free gingival grafts (FGGs) and xenogeneic collagen matrices (XCMs). A combination of the above produced six groups. Two months later, tissue sections were harvested and analysed histomorphometrically.

RESULTS

The median KT height and length were greatest at implants with FGG in both wKT (3.7 and 5.1 mm, respectively) and w/oKT groups (3.7 and 4.6 mm), and at teeth with FGG in wKT groups (3.7 and 6.1 mm) and with APF in the w/oKT groups (3.9 and 4.4 mm). The XCM and APF produced more favourable results at teeth than at implants.

CONCLUSIONS

FGG was advantageous in gaining KT, especially at implants.

A Mapping Review of the Pathogenesis of Peri-Implantitis: The Biofilm-Mediated Inflammation and Bone Dysregulation (BIND) Hypothesis

This mapping review highlights the need for a new paradigm in the understanding of peri-implantitis pathogenesis. The biofilm-mediated inflammation and bone dysregulation (BIND) hypothesis is proposed, focusing on the relationship between biofilm, inflammation, and bone biology. The close interactions between immune and bone cells are discussed, with multiple stable states likely existing between clinically observable definitions of peri-implant health and peri-implantitis. The framework presented aims to explain the transition from health to disease as a staged and incremental process, where multiple factors contribute to distinct steps towards a tipping point where disease is manifested clinically. These steps might be reached in different ways in different patients and may constitute highly individualised paths. Notably, factors affecting the underlying biology are identified in the pathogenesis of peri-implantitis, highlighting that disruptions to the host-microbe homeostasis at the implant-mucosa interface may not be the sole factor. An improved understanding of disease pathogenesis will allow for intervention on multiple levels and a personalised treatment approach. Further research areas are identified, such as the use of novel biomarkers to detect changes in macrophage polarisation and activation status, and bone turnover.

Technical Note on Simplified Free Gingival Graft Using Tack Fixation (sFGG)

Free gingival graft (FGG) is the gold standard procedure for the reliable augmentation of lost keratinized mucosa (KM) around dental implants. This conventional surgical approach has its drawbacks, including limitations in manipulation, the requirement for suturing, postoperative discomfort, and pain. This case report aimed to evaluate the efficacy of a simplified free gingival graft (sFGG) in addressing the issue of inadequate keratinized mucosa around dental implants. Fixation tacks were used to perform the sFGG procedure. Initially, a partial-thickness flap was created and apically repositioned. The gingival graft was harvested from the palate with a narrow profile and securely affixed to the recipient site using 5 mm long fixation tacks. Significant gains in keratinized mucosa were achieved and successfully maintained within 1 year. Consequently, the sFGG technique emerges as a simple and reliable treatment approach for managing inadequate keratinized mucosa around dental implants.

The accuracy of implant placement using a combination of static and dynamic computer-assisted implant surgery in fully edentulous arches: A prospective controlled clinical study

OBJECTIVE

To compare the accuracy of implant position, using a combination of static and dynamic computer-assisted implant surgery (CAIS), with either static, dynamic, or freehand implant placement, in fully edentulous arches.

MATERIALS AND METHODS

Twenty-one patients with a total of 88 fixtures were included. Implants were divided equally into four groups: a combination of static and dynamic CAIS (SD group), static CAIS (S group), dynamic CAIS (D group), and freehand placement (FH group). Angular deviation, as well as the 3D platform and apex deviations, were measured for all groups. Furthermore, the direction of implant deviation was recorded and compared.

RESULTS

The FH group showed significantly more deviation compared to all groups, considering all the aspects, and at both the implant platform and apex. A significant difference in angular deviation between the SD and S groups (p < .001), and between the SD and D groups (p < .001) was noted, favoring the SD group. When evaluating implant distribution, the FH group showed a tendency towards the buccal, apical, and distal directions at platform and apex, while in the D group, implants shifted more to the buccal. In contrast, the SD group did not show a trend toward any specific direction. The S and SD groups did not show a statistical significance considering any direction.

CONCLUSIONS

The combination of static and dynamic CAIS increases the accuracy of implant placement in fully edentulous arches when compared with either static or dynamic CAIS alone, as well as freehand placement.

Evaluation of Behavior of Castable versus Machined Solid Abutments for Morse Tapper Implant Connection: A Clinical Retrospective Study

Objective: The primary objective of the present retrospective clinical study was to evaluate and compare the clinical performance presented by castable abutments developed for the MT system versus intermediate machined abutments, specifically regarding prosthetic or implant fractures/loss; the secondary objective was to verify the looseness of the abutments and the behavior of the peri-implant soft tissues. Methods: This clinical retrospective study was conducted on patients rehabilitated between 2019 and 2020. Inclusion criteria were patients in good general health, with an implants-supporting single crown; with solid machined abutments (control group) or castable UCLA abutments; with a connection portion (base) machined in cobalt-chrome (test group) over Morse taper DuoCone implants in the posterior mandible area; and at least two years in function. Clinical assessment was carried out by the same professional, considering the following parameters: (A) prosthetic: (i) loosening of the fixation screw, (ii) fracture of the screw and (iii) the number of times the patient had some type of complication after the installation of the prostheses were evaluated; (B) biological: (i) without keratinized mucosa (KM), (ii) 1 mm or less, (iii) between 1 and 2 mm and (iv) greater than 2 mm of KM width; and the presence or absence of mucositis. Furthermore, radiographic evaluation was performed in order to assess the marginal bone loss. These evaluations permitted to compare the groups analyzed and patients enrolled. Data were statistically analyzed, with the level of significance set at α = 0.05. Results: 79 patients with 120 MT implants were evaluated (80 castable UCLA abutments and 40 machined solid abutments). The follow-up was from 2 to 4 years. There was a 100% implant survival rate. Therefore, the control group showed two fractured abutments (5%) and no abutment loosening (95% for prosthetic survival rate), whereas the test group showed no abutment fracture but nine loosening screws (11.3%) (100% for prosthetic survival rate). Keratinized mucosa was considered thin or absent in 19 implants in the control group (47.5%) and 42 in the test group (52.5%). Mucositis was found in 11 implants in the control group (27.5%) and 27 in the test group (33.8%). A positive correlation was observed between the width of keratinized mucosa and mucositis (r = 0.521, p = 0.002). The mean marginal bone loss was 2.3 mm, ranging from 1.1 to 5.8 mm. No correlation was observed when considering marginal bone loss versus the three parameters (implant diameter, implant length and time of the prosthesis in function). Conclusions: The results suggest that UCLA-type abutments are a viable option for rehabilitating implants with Morse taper connections, suggesting lower fracture risk. Further research is necessary to confirm these findings and thoroughly evaluate the clinical performance and long-term outcomes.