Clinical, radiological, and gene expression analyses in smokers and non-smokers, Part 2: RCT on the late healing phase of osseointegration

Effects of Nitric Oxide Supplementation on the Levels of Interleukin-6 in Saliva after Dental Implant Placement - A Prospective Study

Introduction

The purpose of the study was to evaluate and compare the levels of salivary Interleukin-6 (IL-6) before and after the placement of dental implants in patients who are supplemented with nitric oxide (NO).

Materials and Methods

The study comprised 34 patients, divided into control and study groups (17 in each group). The control group was given a placebo and in the study group, nitric oxide supplement was prescribed, whereas the control group received a placebo. Saliva samples were taken before placement of dental implants, first and third day after the implant placement. The levels of salivary IL-6 were assessed using an enzyme-linked immunosorbent assay test.

Results

Statistical analysis showed a significant P value (<0.05) with respect to IL-6 levels on first and third days after placement of dental implants. Salivary IL-6 levels in the study group declined significantly. On day three, the IL-6 values for the control and study groups were 0.0639 and 0.0443, respectively. Within the groups, it was observed that there was a significant decrease in IL-6 values from day one to day three.

Discussion

The levels of salivary IL-6 reduced from day one to day three more significantly and consistently in patients prescribed with NO supplements post-dental implant placement, suggesting better resolution of inflammation.

Non-invasive sampling procedure revealing the molecular events at different abutments of bone-anchored hearing systems–A prospective clinical pilot study

Purpose

To investigate the molecular activities in different compartments around the bone-anchored hearing system (BAHS) with either electropolished or machined abutments and to correlate these activities with clinical and microbiological findings.

Materials and methods

Twelve patients received machined or electropolished abutments after implant installation of BAHS. Peri-abutment fluid and tissue were collected from baseline to 12 months. Gene expression of cytokines and factors related to tissue healing and inflammation, regeneration and remodelling, as well as bacterial recognition were determined using quantitative-polymerase chain reaction (qPCR). The clinical status was evaluated using the Holgers scoring system, and bacterial colonisation was investigated by culturing.

Results

The gene expression of inflammatory cytokines (IL-8, IL-1β, and IL-10) and bacteria-related Toll-like receptors (2 and 4) was higher in the peri-abutment fluid than at baseline and in the peri-abutment tissue at 3 and 12 months. Conversely, the expression of genes related to tissue regeneration (Coll1a1 and FOXO1) was higher in the tissue samples than in the peri-abutment fluid at 3 and 12 months. Electropolished abutments triggered higher expression of inflammatory cytokines (IL-8 and IL-1β) (in peri-abutment fluid) and regeneration factor FOXO1 (in peri-abutment tissue) than machined abutments. Several cytokine genes in the peri-abutment fluid correlated positively with the detection of aerobes, anaerobes and Staphylococcus species, as well as with high Holger scores.

Conclusion

This study provides unprecedented molecular information on the biological processes of BAHS. Despite being apparently healed, the peri-abutment fluid harbours prolonged inflammatory activity in conjunction with the presence of different bacterial species. An electropolished abutment surface appears to be associated with stronger proinflammatory activity than that with a machined surface. The analysis of the peri-abutment fluid deserves further verification as a non-invasive sampling and diagnostic procedure of BAHS.

Effects of smoking on the bone alkaline phosphatase in peri-implant crevicular fluid and implant stability quotient around implants before loading

We aimed to examine the implant stability quotient (ISQ), alveolar bone level measurements (ABL), and bone alkaline phosphatase (BALP) in peri-implant crevicular fluid (PICF) around implants in smokers and non-smokers before loading in 3 months. 44 dental implants were placed into smoker and non-smoker patients equally. ISQ was measured at baseline and 3 months after surgery. The levels of PICF BALP and alveolar bone were measured. ISQ values significantly increased in smokers and non-smokers in the 3rd month (p < 0.05). ABL measurements were lower at 3 months compared to baseline in both groups (p < 0.05). Although ISQ and ABL values were higher in non-smokers than smokers at 3 months, the difference between the groups did not show any statistical significance. The PICF BALP levels in the 3rd month changed in both groups. But, these differences were insignificant. Although some of the measurements presented differences between the groups during the assessment periods, they were not indicative of the hazardous effects of smoking on bone healing around implants after surgery till functional loading in 3 months. However, smoking is an important factor to be considered for osseo-integration outcomes. Further studies are needed to clarify the influence of smoking on osseo-integration.

Cellular and Molecular Dynamics during Early Oral Osseointegration: A Comprehensive Characterization in the Lewis Rat

OBJECTIVE

There is a need to improve the predictability of osseointegration in implant dentistry. Current literature uses a variety of in vivo titanium (Ti) implantation models to investigate failure modes and test new materials and surfaces. However, these models produce a variety of results, making comparison across studies difficult. The purpose of this study is to validate an oral osseointegration in the Lewis rat to provide a reproducible baseline to track the inflammatory response and healing of Ti implants.

METHODS

Ti screws (0.76 mm Ø × 2 mm length) were implanted into the maxillary diastema of 52 adult male Lewis rats. Peri-implant tissues were evaluated 2, 7, 14, and 30 days after implantation (n = 13). Seven of the 13 samples underwent microtomographic analysis, histology, histomorphometry, and immunohistochemistry to track healing parameters. The remaining six samples underwent quantitative polymerase chain reaction (qPCR) to evaluate gene expression of inflammation and bone remodeling markers over time.

RESULTS

This model achieved a 78.5% success rate. Successful implants had a bone to implant contact (BIC)% of 68.86 ± 3.15 at 30 days on average. Histologically, healing was similar to other rodent models: hematoma and acute inflammation at 2 days, initial bone formation at 7, advanced bone formation and remodeling at 14, and bone maturation at 30. qPCR indicated the highest expression of bone remodeling and inflammatory markers 2-7 days, before slowly declining to nonsurgery control levels at 14-30 days.

CONCLUSION

This model combines cost-effectiveness and simplicity of a rodent model, while maximizing BIC, making it an excellent candidate for evaluation of new surfaces.

An evaluation of peri-implant marginal bone loss according to implant type, surgical technique and prosthetic rehabilitation: a retrospective multicentre and cross-sectional cohort study

To evaluate implant loss (IL) and marginal bone loss (MBL); follow-up period of up to 10 years after prosthetic loading. Retrospective multi-centre cross-sectional cohort study. Double analysis: (1) all the implants (n = 456) were analysed; (2) to allow for possible cluster error, one implant per patient (n = 143) was selected randomly. Statistical analysis: Spearman's correlation coefficient; Kruskal-Wallis (post-hoc U-Mann-Whitney); Chi-square (post-hoc Haberman). (1) Analysing all the implants (456): IL was observed in patients with past periodontitis (6 vs. 2.2%, p < 0.05), short implants (12 vs. 2.8%, p < 0.001) and when using regenerative surgery (11.3 vs. 2.9%, p < 0.001); greater MBL was observed among smokers (0.39 ± 0.52 vs. 0.2 ± 0.29, p < 0.01), maxillary implants (0.28 ± 0.37 vs. 0.1 ± 0.17, p < 0.0001), anterior region implants (0.32 ± 0.36 vs. 0.21 ± 0.33, p < 0.001), external connection implants (0.2 ± 0.29 vs. 0.63 ± 0.59, p < 0.0001), and 2-3 years after loading (p < 0.0001). (2) analysing the cluster (143): IL was observed in smokers (18.8 vs. 3.5%, p < 0.05), splinted fixed crowns (12.9%, p < 0.01), short implants (22.2 vs. 4.0%, p < 0.01) and when using regenerative surgery (19.2 vs. 3.4%, p < 0.01); greater MBL was observed in maxillary implants (0.25 ± 0.35 vs. 0.11 ± 0.18, p < 0.05), in the anterior region (p < 0.05), in the first 3 years (p < 0.01), in external connection implants (0.72 ± 0.71 vs. 0.19 ± 0.26, p < 0.01) and in short implants (0.38 ± 0.31 vs. 0.2 ± 0.32, p < 0.05). There is greater risk in smokers, patients with past periodontal disease, external connection implants, the use of short implants and when regenerative techniques are used. To prevent MBL and IL, implantologists should be very meticulous in indicating implants in patients affected by these host factors.

Evidence-based analysis of the effect of smoking on osseointegrated implant outcome

The outcome of the osseointegrated implant is influenced by various conditions, one of which is smoking. Literature shows conflicting results for the association between smoking and implant success. Hence, the study was conducted to assess the effects of smoking on survival and marginal bone loss of osseointegrated implants. Literature search of published articles in Medline, Scopus, Ovid, and Journal of Web till June 2020 were analyzed for the determined outcomes. Revman 5.4 software was used for the analysis of the study. Of the 437 articles screened, nine were chosen for review and analysis. Meta-analytic results showed that implant success rate was better in nonsmokers than smokers (odds ratio = 0.43, 95% confidence interval = 0.26-0.72, P < 0.0001). Smoking habit does seem to affect the implant outcome of survival and marginal bone loss negatively.

Impact of Smoking Cessation on Periodontitis: A Systematic Review and Meta-analysis of Prospective Longitudinal Observational and Interventional Studies

AIMS

This systematic review aimed to estimate the effect of tobacco smoking cessation on the risk for periodontitis compared to the risk among never-smokers and to evaluate the effect of tobacco smoking cessation on the clinical outcomes of nonsurgical periodontal treatment.

METHODS

Electronic searches were performed in PubMed, Scopus, and Embase. Search strategy included MeSH and free terms: periodontitis, periodontal diseases, smoking, tobacco use, tobacco, tobacco products, cigarette, pipe, and cigar. Only original prospective longitudinal observational and interventional studies that investigated the association between smoking cessation and periodontitis onset or progression were included. Meta-analyses were conducted to summarize the evidence.

RESULTS

A total of 2743 articles were identified in electronic searches; out of which only six were included in the meta-analysis. Pooled estimates showed that the risk of periodontitis incidence or progression among those who quit smoking was not significantly different from the risk for never-smokers (risk ratio [RR] = 0.97; 95% confidence interval [CI] = 0.87% to 1.08%). Smokers had approximately 80% higher risk of periodontitis than quitters (RR = 1.79; 95% CI = 1.36% to 2.35%) and never-smokers (RR = 1.82; 95% CI = 1.43% to 2.31%). Periodontal therapy resulted in up to 0.2 mm (95% CI = -0.32% to -0.08%) higher gain in attachment level and extra 0.32 mm (95% CI = 0.07% to 0.52%) reduction in pocket depth among quitters over nonquitters after short follow-up (12-24 months).

CONCLUSIONS

Few studies on the topic were identified. Smoking cessation reduced the risk for periodontitis onset and progression, and improved the outcomes of nonsurgical periodontal therapy.

IMPLICATIONS

This review provides the first quantitative evidence of the impact of smoking cessation on the risk for periodontitis onset and progression. The findings have demonstrated that the risk for periodontitis becomes comparable to that of never-smokers and that nonsurgical periodontal treatment outcomes improve after smoking cessation. Dental professionals ought to consider smoking cessation interventions as a relevant component of the periodontal therapy.

The Long-Term Effect of Smoking on 10 Years' Survival and Success of Dental Implants: A Prospective Analysis of 453 Implants in a Non-University Setting

Background: The purpose of this study was to compare the survival and peri-implant bone loss of implants with a fluoride-modified surface in smokers and non-smokers. Material and Methods: All patients referred for implant treatment between November 2004 and 2007 were scrutinized. All implants were placed by the same surgeon (B.C.). The single inclusion criterion was a follow-up time of at least 10 years. Implant survival, health, and bone loss were evaluated by an external calibrated examiner (S.W.) during recall visits. Radiographs taken at recall visits were compared with the post-surgical ones. Implant success was based on two arbitrarily chosen success criteria for bone loss (≤1 mm and ≤2 mm bone loss after 10 years). Implant survival in smokers and non-smokers was compared using the log-rank test. Both non-parametric tests and fixed model analysis were used to assess bone loss in both groups. Results: A total of 453 implants in 121 patients were included for survival analysis, and 397 implants in 121 patients were included for peri-implant bone-loss analysis. After a mean follow-up time of 11.38 years (SD 0.78; range 10.00–13.65), 33 implants out of 453 initially placed had failed in 21 patients, giving an overall survival rate of 92.7% and 82.6% on the implant and patient level, respectively. Cumulative 10 years’ survival rate was 81% on the patient level and 91% on the implant level. The hazard of implant loss in the maxilla was 5.64 times higher in smokers compared to non-smokers (p = 0.003). The hazard of implant loss for implants of non-smokers was 2.92 times higher in the mandible compared to the maxilla (p = 0.01). The overall mean bone loss was 0.97 mm (SD 1.79, range 0–17) at the implant level and 0.90 mm (SD 1.39, range 0–7.85) at the patient level. Smokers lost significantly more bone compared to non-smokers in the maxilla (p = 0.024) but not in the mandible. Only the maxilla showed a significant difference in the probability of implant success between smokers and non-smokers (≤1 mm criterion p = 0.003, ≤2 mm criterion p = 0.007). Taking jaw into account, implants in smokers experienced a 2.6 higher risk of developing peri-implantitis compared to non-smokers (p = 0.053). Conclusion: Dental implants with a fluoride-modified surface provided a high 10 years’ survival with limited bone loss. Smokers were, however, more prone to peri-implant bone loss and experienced a higher rate of implant failure, especially in the upper jaw. The overall bone loss over time was significantly higher in smoking patients, which might be suggestive for a higher peri-implantitis risk. Hence, smoking cessation should be advised and maintained after implant placement from the perspective of peri-implant disease prevention.

Does Smoking Impair Bone Regeneration in the Dental Alveolar Socket?

Smoking is a major risk factor for dental implant failure. In addition to higher marginal bone loss around implants, the cellular and molecular responses to injury and implant physicochemical properties are also differentially affected in smokers. The purpose of this work is to determine if smoking impairs bone microstructure and extracellular matrix composition within the dental alveolar socket after tooth extraction. Alveolar bone biopsies obtained from Smokers (> 10 cigarettes per day for at least 10 years) and Ctrl (never-smokers), 7-146 months after tooth extraction, were investigated using X-ray micro-computed tomography, backscattered electron scanning electron microscopy, and Raman spectroscopy. Both Smokers and Ctrl exhibited high inter- and intra-individual heterogeneity in bone microstructure, which varied between dense cortical and porous trabecular architecture. Regions of disorganised/woven bone were more prevalent during early healing. Remodelled lamellar bone was predominant at longer healing periods. Bone mineral density, bone surface-to-volume ratio, mineral crystallinity, the carbonate-to-phosphate ratio, the mineral-to-matrix ratio, the collagen crosslink ratio, and the amounts of amino acids phenylalanine and proline/hydroxyproline were also comparable between Smokers and Ctrl. Bone microstructure and composition within the healing dental alveolar socket are not significantly affected by moderate-to-heavy smoking.

Influence of marginal bone loss on peri-implantitis: Systematic review of literature

Background

The marginal bone of dental implants is subjected to slight load modifications over time, conditioning implant survival. Objective: Perform a systematic review of the literature analyzing the factors that contribute to marginal bone loss (MBL) and the subsequent development of peri-implantitis.

Material and Methods

Bibliographic research in the databases PubMed, Medline and Scopus between 2010 and 2018 was performed. The inclusion criteria were articles published in the last 10 years and that were in English or Spanish, that were carried out on humans, that were cohort studies, that included cases and controls or that used randomized clinical trials. Exclusion criteria removed articles that contained clinical cases, case series or systematic reviews.

Results

A total of 90 articles were analyzed that examined all the factors reported in the literature, such as idiosyncratic factors, toxic habits, systemic drugs and implant characteristics (diameter, length, type surface, implant connection, implant design and type of platform at the moment of the prosthetic load). Discussion: Patient characteristics and associated pathologies must be taken into account when assessing MBL. MBL in all dental implants can be considered independent of the type of prosthetic rehabilitation and the moment of load; this was emphasized. The MBL is smaller in dental implants with rough surfaces, switch platforms and infracrestal localization, as they are of multifactorial origin.

Conclusions

All the reviewed articles maintain a common criterion regarding the concept and measurement of the MBL and highlighting the importance of radiodiagnosis for quantification. Longterm prospective studies with unified criteria are needed to reduce bias by identifying the most relevant factors in MBL.

Key words:Marginal bone loss, dental implant, peri-implantitis.

Mapping of inflammatory biomarkers in the peri-implant crevicular fluid before and after the occlusal loading of narrow diameter implants

OBJECTIVE

To monitor the cytokine release patterns in the peri-implant crevicular fluid (PICF) and to investigate which factors affect the success rate of narrow diameter implants (NDI) during the first year.

MATERIAL AND METHODS

Mandibular implant overdentures (IOD) retained by 2 NDI were installed in 16 clinically atrophic edentulous patients. The following parameters were monitored during the first year: (i) peri-implant health parameters (plaque index (PI), calculus presence (CP), gingival index (GI), probing depth (PD) and bleeding on probing (BoP); (ii) cytokine concentrations in the PICF (TNF-α, IL-1β, IL-6, IL-10); (iii) implant stability quotient (ISQ); (iv) marginal bone level (MBL) and bone level change (BLC); (v) implant success. The insertion torque, bone type, mandibular atrophy, time since edentulism, and smoking habits were also recorded. All data were analyzed using multivariable multilevel mixed-effects regression models.

RESULTS

The variability in the TNF-α release patterns temporarily reduced at weeks (w) 8-12, while the IL-1β concentrations remained low until they peaked at w48 [p < 0.05; + 177.55 pg/μl (+ 96.13 - + 258.97)]. Conversely, IL-10 release decreased significantly at w48 [p < 0.05; - 456.24 pg/μl (- 644.41 - - 268.07)]. The PD and ISQ decreased significantly (p < 0.05) over the follow-up period, while the MBL was stable after w48 with a BLC of 0.12 ± 0.71 mm. The overall success rate was 81.3%, and was influenced by TNF-α, IL-1β, IL-10, PI, GI, PD, smoking, and time since edentulism.

CONCLUSION

Pro- and anti-inflammatory cytokine release was balanced during the first 24 weeks. The GI, smoking, and time since edentulism are the most important factors determining the implant success.

CLINICAL RELEVANCE

The study contributes to the understanding of the osseointegration process in a clinically atrophic population rehabilitated with IOD, and highlights the importance of monitoring clinical peri-implant health-related parameters, smoking habit, and time since edentulism to predict implant success rates.

The effect of smoking on the marginal bone loss around implant-supported prostheses

INTRODUCTION

Implantology has led to several changes in the planning process involved in the application of dental prostheses to diminish bone level changes along the margins of dental implants. However, the relationship between smoking and marginal bone loss around dental implants, supporting both fixed and removable prostheses has not been investigated. We hypothesize that the design of different prostheses alter the effects of smoking, which consequently affects the amount of supporting alveolar bone.

METHODS

In this study, we included 137 implants in the ‘implant-supported fixed prostheses’ (ISFP) group (31 smokers, 106 non-smokers) and 94 implants (21 smokers, 73 non-smokers) in the ‘implant-supported removable prostheses’ (ISRP) group. The corresponding patients were examined in routine recall sessions conducted at 6, 12 and 24 months after the placement of the dental prostheses. The recorded clinical periodontal parameters were the presence/ absence of a plaque index, bleeding index, and the probing depths. These periodontal parameters were assessed in conjunction with marginal bone level measurements. Comparative bone level measurements were obtained from radiographical images at ×20 magnification using the CorelDraw 11.0 software program. Statistical analysis was performed using the SPSS Statistical Software version 21.0.

RESULTS

The overall clinical parameters were found to be poorer in smokers than in non-smokers (p<0.05). In all the groups, time-dependent bone loss was observed. However, among the patients with ISRPs, smokers were associated with significantly greater marginal bone loss compared to patients with ISFPs (p<0.05).

CONCLUSIONS

In smokers with dental ISRPs, the marginal bone loss rates are likely to reach critical levels. Therefore, after the placement of prostheses, strict recall periods with a dental professional should be observed, and their guidance should be implemented in order to monitor the health of the bones around the implants.