The effect of keratinized mucosa on the severity of peri-implant mucositis differs between periodontally healthy subjects and the general population: a cross-sectional study

Efficacy of free gingival grafting to augment keratinized mucosa around dental implants in posterior regions after restorative procedures: A retrospective clinical study

STATEMENT OF PROBLEM

Data on the shrinkage of free gingival grafts (FGGs) vary. Most studies have analyzed grafts in nonmolar sites because of measurement limitations and have addressed the changes in grafts and keratinized mucosa width (KMW) only in the early healing phase.

PURPOSE

The purpose of this retrospective clinical study was to assess the dimensional changes of an FGG in the posterior regions and their influencing factors, with the aim of obtaining sufficient and stable KMW after restoration.

MATERIAL AND METHODS

A total of 77 implants in 40 participants who had undergone an FGG surgery were recruited. Graft sizes during surgery and the surface areas of keratinized mucosa at the follow-up visit after restorations were compared by digital analysis and verified by clinical measurements and photographs. The association between shrinkage and the graft sizes, implant location, and sex and age of the participants was evaluated. The influence of the shrinkage of FGG on the KMW after restoration was analyzed by multivariable linear regression with generalized estimating equation (GEE) models.

RESULTS

The mean ±standard deviation shrinkage of FGG around implants in the posterior regions was 24.76 ±14.77%, and the mean ±standard deviation KMW was 4.16 ±1.77 mm at the follow-up visit. Larger grafts had a statistically higher shrinkage ratio (P<.001). No statistically significant difference was found regarding the effect of implant location, sex, and age on the shrinkage of FGG and final KMW (P>.05). The mean ±standard deviation follow-up period after restoration was 12.45 ±7.73 months CONCLUSIONS: Free gingival grafting was found to be a predictable treatment approach for augmentation of KMW around implants in the posterior region after the fabrication of prostheses as long as grafts of sufficient size were placed. Stable outcomes were shown in the study participants in the follow-up period of up to 3 years.

Spontaneous regeneration of keratinized tissue at implants and teeth

AIM

To investigate the spontaneous regeneration of the implanto-mucosal and dento-gingival unit after complete removal of keratinized tissue (KT).

MATERIALS AND METHODS

One hemi-mandible per dog (n = 4) was allocated to receive three dental implants (test sites, premolar region), whereas three premolars on the contralateral side were controls. After osseointegration, the entire KT (buccal + lingual) was surgically excised on all test and control sites, leaving the bone exposed. Clinical measurements were performed before excision (T0 ) and after 12 weeks (T1 ). Following healing, the animals were euthanized, and the specimens were histologically processed. Descriptive statistical analyses were performed.

RESULTS

Clinical measurements revealed that at T1 , on all teeth, a band of KT was spontaneously regenerated (mean width: 2.60 ± 0.66 mm), whereas on implants, KT was detected only occasionally at mesial or distal but not at buccal sites (mean total: 0.35 ± 0.53 mm; p < .0001). Histologically, spontaneous regeneration of the dento-gingival unit was evident, displaying masticatory mucosa. At the implant sites, on the other hand, the implanto-mucosal unit was characterized by a non-keratinized epithelium and elastic fibres, indicating the characteristics encountered in alveolar mucosa.

CONCLUSION

After excision of KT at implant sites, the spontaneous regeneration of the soft tissue is characterized by a non-keratinized epithelium typical for alveolar mucosa, while at tooth sites the spontaneous regeneration was characterized by soft tissue resembling gingiva.

Supportive care for the prevention of disease recurrence/progression following peri-implantitis treatment: A systematic review

OBJECTIVES

This systematic review aimed to evaluate the efficacy of supportive care provision, frequency and protocol in patients treated for peri-implantitis, as reported in prospective and retrospective studies of at least 3-years duration.

MATERIALS AND METHODS

A systematic search of three electronic databases was undertaken up to 21 July 2022 and supplemented by hand-search to identify studies that included participants treated for peri-implantitis and followed for at least 3 years. Owing to high heterogeneity, a meta-analysis was not appropriate, and therefore, data and risk of bias were explored qualitatively. PRISMA guidelines for reporting were followed.

RESULTS

The search identified 2596 studies. Of 270 records selected during screening, 255 were excluded through independent review and 15 studies (10 prospective and 5 retrospective, with at least 20 patients) were retained for qualitative assessments. Study designs, population characteristics, supportive care protocols and reported outcomes varied markedly. Thirteen of the 15 studies had low risk of bias. Supportive peri-implant care (SPIC) following different surgical peri-implantitis treatment protocols and with recall intervals varying between 2 months and annually resulted in peri-implant tissue stability (no disease recurrence or progression) ranging from 24.4% to 100% at patient level and from 28.3% to 100% at implant level. Sevenhundred and eighty-five patients with 790 implants were included in this review.

CONCLUSIONS

Provision of SPIC following peri-implantitis therapy may prevent disease recurrence or progression. Insufficient evidence is available to identify (i) a specific supportive care protocol for secondary prevention of peri-implantitis, (ii) the effect of adjunctive local antiseptic agents in the secondary prevention of peri-implantitis and (iii) the impact of frequency of supportive care measures. Prospective, randomised, controlled studies designed to evaluate supportive care protocols are needed in future.

The keratinized mucosa width at partially edentulous molar sites and its associated factors: a pilot study

BACKGROUND

Assessment of the keratinized mucosa width (KMW) at edentulous sites is important for the subsequent implant treatment design. This pilot study aimed to evaluate the characteristics of the KMW at edentulous molar sites and explore the associated factors.

METHODS

A total of 150 patients with 222 edentulous molar sites were included. The buccal KMW of the edentulous molar sites was measured during implant treatment planning. Potentially associated factors, including age, sex, smoking status, location, reasons for tooth loss/extraction, gingival phenotype (GP) and keratinized gingival width (KGW) of the adjacent teeth, were collected and analyzed. The Shapiro‒Wilk test, Student's t test, one-way ANOVA, generalized estimation equations (GEEs) and linear regression analysis were used for data analysis at α = 0.05.

RESULTS

The buccal KMW at edentulous molar sites was 3.97 ± 2.06 mm, and 41.9% of sites presented with KMW < 4 mm. The mean KMWs of the maxillary sites were significantly higher than that those of the mandibular sites (4.96 ± 2.05 mm vs. 3.41 ± 1.85 mm, respectively). In total, 54.7%, 46.5%, 29.8%, and 0.0% of mandibular first and second molar sites and maxillary first and second molar sites, respectively, displayed a KMW of < 4 mm. Statistically significant linear correlations were found between KMW and GP (r = 0.161, p = 0.025) and between KMW and KGW of the adjacent teeth (r = 0.161, p = 0.023), while other factors were found to have no significant association.

CONCLUSION

Within the limitations of the present study, the KMW at edentulous molar site was related to the location of molar tooth loss/extraction. The GP and KGW of the adjacent teeth of edentulous molar sites were also associated with their KMW, which was probably attributed to the continuity of the adjacent soft tissue.

The Characteristics of Microbiome and Cytokines in Healthy Implants and Peri-Implantitis of the Same Individuals

AIM

To characterize the profile of submucosal microbiome and cytokine levels in peri-implant crevicular fluid (PICF) from clinically healthy implants and peri-implantitis in the same individuals.

MATERIAL AND METHODS

A total of 170 patients were screened and, finally, 14 patients with at least one healthy implant and one peri-implantitis implant were included. Submucosal microbiota and cytokines from 28 implants were analyzed using 16S rRNA gene sequencing and multifactor assays, respectively. Correlations of clinical indexes and microbiota or cytokines were analyzed using Spearman's correlation coefficient. A random forest classification model was constructed.

RESULTS

Peri-implantitis sites harbored higher microbial diversity, as well as more Gram-negative bacteria and anaerobic bacteria, compared with healthy implants sites. The genera of Peptostreptococcaceae XIG-1, Treponema, Porphyromonas, and Lachnospiraceae G-8, as well as the cytokines of IL-17A, IL-6, IL-15, G-CSF, RANTES, and IL-1β were significantly higher in peri-implantitis than healthy implants. Furthermore, these genera and cytokines had positive relationships with clinical parameters, including probing depth (PD), bleeding on probing (BOP), and marginal bone loss (MBL). The classification model picked out the top 15 biomarkers, such as IL-17A, IL-6, IL-15, VEGF, IL-1β, Peptostreptococcaceae XIG-1, Haemophilus, and Treponema, and obtained an area under the curve (AUC) of 0.85.

CONCLUSIONS

There are more pathogenic bacteria and inflammatory cytokines in peri-implantitis sites, and biomarkers could facilitate the diagnosis of peri-implantitis.

Retrospective Study of the Association between Peri-Implantitis and Keratinized Mucosa

1. Background: Peri-implantitis affects a high percentage of patients treated with dental implants. Among the risk factors that can cause this pathology, limited evidence exists regarding the absence of keratinized mucosa. The main objective of this study was to compare the amount of keratinized mucosa around healthy implants versus implants in patients with peri-implantitis, in order to analyze its influence on esthetics and the development of this pathology, and to study the possible influence of keratinized mucosa on various clinical parameters. 2. Methods: A retrospective case-control study was carried out in which 203 implants were evaluated, 103 of which presented a healthy peri-implant state, versus 100 which had peri-implantitis. The following elements were recorded: keratinized mucosa, recession, plaque index, bleeding, suppuration, probing depth, and bone level. 3. Results: Keratinized mucosa was present in 51% of the peri-implantitis group versus 97.1% of the healthy implants. In implants without keratinized mucosa, both recession and plaque index, bleeding on probing (96.2%), suppuration (57.7%), mean probing depth and bone level were higher. Implants without keratinized mucosa presented worse esthetics. 4. Conclusions: Absence of Keratinized mucosa around dental implants seems to be associated with the appearance of peri-implantitis modifying certain clinical parameters: there is a greater probability of recession, bleeding, suppuration, deficient hygiene, greater probing depth and greater bone loss in implants without keratinized mucosa.

Bacterial-Specific Induction of Inflammatory Cytokines Significantly Decreases upon Dual Species Infections of Implant Materials with Periodontal Pathogens in a Mouse Model

Cytokine profiles are often perturbed after infections of medical implants. With a non-invasive in vivo imaging system, we report in a mouse model that interferon expression after infection of subcutaneous implants with Streptococcus oralis, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Treponema denticola (alone or as a combination) was species-specific, persisted longer in the presence of implants, and notably decreased upon dual species infections. This type I interferon expression disappeared within two weeks; however, histology of implant–tissue interface indicated high recruitment of immune cells even after three weeks. This was suggestive that biomaterial-associated infections could have prolonged effects, including the systemic stimulation of inflammatory cytokines. The present study investigated the systemic impact of this chronic peri-implant inflammation on the systemic expression of inflammatory cytokines (23) using a multiplex assay. Initially, the cytokine measurement in murine fibroblasts exposed to periodontal pathogens remained limited to the expression of five cytokines, namely, IL-6, G-CSF, CXCL-1/KC, MCP-1 (MCAF), and IL-12 (p40). The systemic determination of cytokines in mice increased to 19 cytokines (IL-1α, IL-2, IL-3, IL-5, IL-6, IL-9, IL-12 (p40), IL-12 (p70), IL-13, IL-17A, CCL-11/Eotaxin, G-CSF, IFN-γ, CXCL1/KC, MCP-1 (MCAF), MIP-1α/CCL3, MIP-1β/CCL4, CCL5/RANTES, and TNF-α). Systemic induction of cytokines was species-specific in the mouse model. The cytokine induction from infected implants differed significantly from sole tissue infections and sterile implants. Notably, systemic cytokine induction decreased after infections with dual species compared to single species infections. These findings describe the systemic effect of chronic peri-implant inflammation on the systemic induction of inflammatory cytokines, and this effect was strongly correlated to the type and composition of initial infection. Systemic modulations in cytokine expression upon dual species infections exhibit an exciting pattern that might explain the complications associated with biomaterial-related infection in patients. Moreover, these findings validate the requirement of multispecies infections for pre-clinical studies involving animal models.

Evaluation of keratinized gingiva changes with buccal-based modified palatal flap in anterior maxillary implants

Background. Studies have shown a significant relationship between the width and thickness of keratinized gingiva around the implant and changes in marginal bone level, with a significant effect on the health and esthetic of tissues around the implant, especially in the anterior region of the maxilla, which is an esthetic area. Methods. Ten patients referring to the Faculty of Dentistry seeking implant placement in the anterior maxilla were included in the study. The connective tissue of the palatal gingiva of the surgical site was folded to the buccal aspect with the buccal base, and the thickness and width of keratinized gingiva around the buccal surface of each implant were measured in three time intervals, including before surgery and 6 and 12 weeks after surgery. Based on the results of the Kolmogorov-Smirnov test, Friedman test and repeated-measures ANOVA were used to analyze the data. Results. The intervention significantly affected changes in the gingival thickness. After the intervention, gingival thickness significantly increased compared to the baseline (P<0.05). The results also showed that the intervention did not significantly affect the width of keratinized gingiva. The width of keratinized gingiva at baseline was not significantly different from the two time intervals after intervention (P>0.05). Conclusion. Buccal-based modified palatal flap in anterior maxillary implants increased the thickness of keratinized gingiva, with no significant effect on the keratinized gingiva width.

Removable denture is a risk indicator for peri-implantitis and facilitates expansion of specific periodontopathogens: a cross-sectional study

Background

The prevalence of peri-implantitis ranges between 7 and 38.4% depending on risk indicators such as smoking, diabetes mellitus, lack of periodontal maintenance program, and history or presence of periodontitis. Currently, the possible effect of the type of superstructure on peri-implant health is unclear. This cross-sectional study aims to investigate the influence of the superstructure on the prevalence of peri-implant mucositis, peri-implantitis and peri-implant dysbiosis.

Methods

During a 32-month recruitment period dental implants were assessed to diagnose healthy peri-implant tissues, mucositis or peri-implantitis. The study included 1097 implants in 196 patients. Out of all peri-implantitis cases 20 randomly chosen submucosal biofilms from implants with fixed denture (FD) originating from 13 patients and 11 biofilms from implants with removable dentures (RD) originating from 3 patients were studied for microbiome analysis. Composition of transcriptionally active biofilms was revealed by RNAseq. Metatranscriptomic profiles were created for thirty-one peri-implant biofilms suffering from peri-implantitis and microbiome changes associated with superstructure types were identified.

Results

16.41% of the implants were diagnosed with peri-implantitis, 25.00% of implants with RD and 12.68% of implants with FD, respectively. Multivariate analysis showed a significant positive association on patient (p =  < 0.001) and implant level (p = 0.03) between the prevalence of peri-implantitis and RD. Eight bacterial species were associated either with FD or RD by linear discriminant analysis effect size method. However, significant intergroup confounders (e.g. smoking) were present.

Conclusions

Within the limitations of the present work, RDs appear to be a risk indicator for peri-implantitis and seem to facilitate expansion of specific periodontopathogens. Potential ecological and pathological consequences of shift in microbiome from RDs towards higher activity of Fusobacterium nucleatum subspecies animalis and Prevotella intermedia require further investigation.

Influence of physical activity on periodontal health in patients with type 2 diabetes mellitus. A blinded, randomized, controlled trial

Objectives

The aim was to investigate the effect of physical activity on periodontal health and HbA1c levels in patients with type 2 diabetes mellitus (T2DM) over a period of 6 months.

Materials and methods

Thirty-seven patients with non-insulin-dependent T2DM were included in the study. The intervention group (n=20) performed physical activity over a period of 6 months. The control group (n=17) did not receive any intervention. Baseline and final examinations included dental parameters and concentrations of glycosylated hemoglobin (HbA1c) and high-sensitivity C-reactive protein (hsCRP).

Results

Physical activity showed a positive effect on periodontal health. Both the BOP (p= 0.005) and the severity of periodontitis (p= 0.001) were significantly reduced in the intervention group compared to the control group. Furthermore, HbA1c levels were reduced (p= 0.010) significantly in the intervention group while hsCRP levels significantly increased in the control group (p= 0.04).

Conclusions

Within the limitations of this randomized, controlled trial, physical activity over a period of 6 months is a health-promoting measure for patients with T2DM and improves both periodontal health and HbA1c concentrations.

The effect of adjuvant oral irrigation on self-administered oral care in the management of peri-implant mucositis: A randomized controlled clinical trial

OBJECTIVES

This single-blinded randomized clinical trial evaluated the effect of adjuvant oral irrigation in addition to self-administered oral care on prevalence and severity of peri-implant mucositis.

MATERIAL & METHODS

After randomization, patients suffering from peri-implant mucositis were assigned to the following: Group 1 (control) received oral hygiene instruction following a standardized protocol, including a sub- and supramucosal mechanical debridement. Group 2 and 3 additionally were instructed to use an oral irrigator with either water or 0.06% CHX solution. One implant per patient was considered for examination. Clinical examinations included Probing Depth, Bleeding on Probing (BOP-positive sites), and Modified Plaque and Gingival Index. A surrogate variable (mucositis severity score) was applied measuring severity of disease. Statistical analysis included linear regression models and sensitivity analysis.

RESULTS

Sixty periodontally healthy patients were examined for presence and severity of peri-implant mucositis. 70% of all patients reached complete resolution of disease after 12 weeks. The prevalence of peri-implant mucositis after 12 weeks was 50% in group 1, 35% in group 2, and 5% in group 3. Average BOP-positive sites were reduced in all groups after 12 weeks (mean change from baseline: group 1: -1.5; group 2: -1.8; group 3: -2.3).

CONCLUSION

Within the limits of the study, adjuvant use of an oral irrigator with 0.06% CHX in addition to mechanical biofilm removal and oral hygiene instruction can reduce the presence and severity of peri-implant mucositis after 12 weeks.