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In our previous article, we observed and measured a spontaneous growth in the coronal direction of the keratinized tissues present around implants. This growth involved both free margins and interdental papillae, and we indicated our hypothesis on the probable cause of this still-unexplained phenomenon. The growth of oral soft tissues involves several other structures, such as the linea alba and tongue indentation. Our idea holds that growth of these tissues is generated by the negative intraoral pressure created in the oral phase of swallowing and the subsequent resting position, which through the resulting suction causes a shift of these soft structures in the gaps around the dental crowns. Other hypotheses have been suggested in the past to understand this phenomenon of soft tissue growth, which still lacks data supporting etiological evidence. The purpose of this article is to thoroughly analyze and verify our model by comparing the clinical observations with citations and examples from the literature, combined with notions of physiology, biology, and physics that help in clarifying these events. To better explain the mechanisms of oral soft tissue growth, photographs of clinical cases paradigmatic of the phenomenon are shown.

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Peri-implant soft tissue deficiency (PSTD) is a significant factor impacting aesthetics, particularly in the anterior zone, where labial bone resorption and thin peri-implant phenotypes are common. The occurrence of a gray color around the implant fixture due to PSTD can be aesthetically concerning in the esthetic zone. In cases involving natural teeth, autogenous soft tissue grafts such as subepithelial connective tissue grafts (SCTGs), free gingival grafts (FGGs), and coronally advanced flaps (CAFs) are commonly utilized. However, there are limited reports of using bone grafts in conjunction with these techniques for modifying the gingival phenotype around both teeth and implants. In the presented cases where PSTD resulted in visible gray coloration of the implant fixture in the esthetic zone, mechanical and chemical decontamination of the exposed implant surface was performed using a titanium brush and tetracycline (Tc) HCl. Subsequently, to enhance peri-implant mucosa thickness and mask the titanium color, simultaneous SCTG and bone grafting procedures were conducted. Within the limitations of these case reports, successful esthetic outcomes were achieved and maintained without recurrence for 3-6 years following the simultaneous subepithelial connective tissue graft and bone graft procedures. These findings suggest the potential efficacy of this combined approach in addressing PSTD and enhancing aesthetic results around dental implants, though further studies are needed to validate these outcomes.

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Enhanced mucosal sealing around titanium implants can reduce complications such as peri-implantitis. The present study aims to investigate the mucosal healing at the early stage around the protease activated receptor 4-agonist peptide (PAR4-AP)- or perpendicularly protruded type I collagen (pCol)-treated titanium implants. A total of 72 implants were placed in 36 rats in the study. Following extractions, two tissue-level implants among the following three different surfaces, PAR4-AP-coated (PAR4 group, n = 24), pCol-treated (pCol group, n = 24) and non-treated (control group, n = 24) ones, were placed in the maxillae of each rat based on a split-mouth design. The specimens retrieved at 8 h (n = 8 per group), 3 days (n = 8 per group), and 2 weeks (n = 8 per group), were immunostained and tissue-cleared, and the signals of laminin-5 and collagen fibers were observed under multiphoton microscopy. Statistical analyses were performed using linear mixed model with post hoc tests to compare differences between the groups. While there was no intergroup difference at 8 h, the laminin-5 at 3 days was more abundant near the PAR4-group-surface, and its area was significantly larger in the PAR4 group (0.0204 ± 0.0194 mm2 ) than the control (0.0019 ± 0.0025 mm2 , p = .001) and pCol (0.0023 ± 0.0022 mm2 , p < .001) groups. The pCol group showed a significantly larger area of collagen fibers (0.0230 ± 0.0148 mm2 ) compared to the control (0.0035 ± 0.0051 mm2 , p = .002) and PAR4 (0.0031 ± 0.0057 mm2 , p < .001) groups at 3 days. At 3 days and 2 weeks, the collagen fiber orientation of the pCol group showed a more perpendicular manner compared to the control and PAR4 groups. The signal of basal lamina and collagen fibers were stronger around the PAR4-AP- and pCol-treated titanium surfaces, respectively during the early healing stage. This could have implications for improved mucosal sealing around dental implants, potentially reducing complications such as peri-implantitis.

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AIM: To investigate the healing after heterotopic mucosa transpositioning at dental implants and teeth. MATERIALS AND METHODS: One hemimandible per dog (n = 4) was allocated to receive 3 implants (test), whereby 3 premolars on the contralateral side served as controls. After osseointegration, a Z-plasty was performed on the buccal aspect of the test and control sites to heterotopically move the zone of keratinized tissue (KT) into a region with non-keratinized tissue (nKT) and vice versa. Clinical measurements were performed before (T0) and at 12 weeks following heterotopic transposition (T1). Thereafter, specimens were processed for histological analysis. RESULTS: Clinical measurements revealed that at T1, a band of KT was reestablished at teeth (mean: 2.944 ± 1.866 mm), whereas at implants, the transpositioned nKT resulted in a mucosa without any signs of keratinization (mean: 0 mm; p < .0001). At implant sites, the probing attachment level loss was more pronounced compared to tooth sites (-1.667 ± 1.195 mm and -1.028 ± 0.878 mm, respectively; p = .0076). Histologically, the transpositioned nKT, was accompanied by the formation of KT at the tooth but not at implant sites. The supracrestal soft tissues were statistically significantly higher at tooth compared to implant sites (2.978 ± 0.483 mm and 2.497 ± 0.455 mm, p = .0083). The transpositioned KT remained mostly unaltered in its morphological characteristics. CONCLUSIONS: The findings of this study indicate that: (a) transpositioned KT may retain its morphological characteristics; and (b) transpositioned nKM was accompanied by the formation of KT at the tooth but not at implant sites.

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The present study aimed to evaluate the peri-implant tissue response and marginal bone levels of immediately loaded narrow diameter dental implants. In this study, 10 patients with single maxillary anterior edentulous space were included. Implants were placed and immediate provisional crown was given without any centric or eccentric contacts. After three months, a definitive restoration was placed. All the clinical and radiographical parameters were evaluated.

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BACKGROUND: The morphologic and dimensional alveolar bone is significant for resorption in the first 3 months after tooth removal because they restrict treatment outcomes with respect to function and esthetic. Following teeth extraction, the width and height of the alveolar ridge contour are reduced in both the horizontal and vertical dimensions. Following implant placement, the gingival morphology should be changed minimally compared to pre-extraction. Surrounding natural-like tissue is also an ultimate goal of the dental implant treatment, which is correlated with the cervical third contour on the anatomical tooth, for comfortable cleansing, food impaction avoidance, and esthetics. PURPOSE: To evaluate the peri-implant soft tissue changes after immediate implant placement (IIP) with the use of a customized titanium healing abutment in the posterior teeth. METHOD: Digital impressions using the intraoral scanner (MEDIT i500) were taken from 30 patients. Customized titanium healing abutments were designed and milled before extraction. Flapless extractions were done using surgical guides, 32 immediate implants placement were done in posterior areas, and healing abutments were placed. Soft tissues were scanned during pre-operation, and post-surgery during the 1st, 3rd, and 6th months. A 3D analysis program (Final Surface) evaluated the gingival margin distance, height, contour width, and volume in each period. SPSS was used to analyze the data with a p-value = 0.05. The between-time interval comparisons were done and the analysis was done using a Multivariate test. RESULTS: Customized titanium healing abutments used in immediate implantation maintained optimal peri-implant mucosa. In intermittent periods, there was no significant reduction in all aspects of the margin distances and heights. During the entire period, the margin height reduction on the buccal, lingual, mesial, and distal was 0.63 mm, 0.93 mm, 0.08 mm, and 0.24 mm, respectively, and contour width reduction on the buccal, lingual, and buccolingual was 0.59 mm, 0.43 mm, and 1.03 mm, respectively. There was a significant reduction in the total buccolingual contour width in the 1st month and total volume in the 3rd to 6th months. CONCLUSIONS: Immediate implant placement with customized titanium healing abutment can achieve the optimal peri-implant mucosa and this protocol is an alternative for soft tissue management.

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PURPOSE: The objective of this study was to compare patient-reported outcomes (PROs) of peri­implant soft tissue inflammation and aesthetics around single-tooth implants in the anterior maxillary region with three different implant-abutment interface designs. METHODS: Participants were randomized to one of three different types of implant-abutment interface designs [Conical (CI), flat-to-flat (FI), and Platform Switched (PS)]. Implants and provisional crowns with prefabricated titanium abutments were placed 5 months following extraction and/or ridge augmentation. Permanent ceramic crowns with zirconia abutments were placed after 12 weeks. To assess PROs, appearance and inflammation questionnaires were completed from provisional crown placement to the 3-year follow-up. RESULTS: Tooth appearance at the 3-year follow-up revealed a difference amongst CI, FI and PS implants (p=0.049; Kruskal-Wallis test). PS was rated better than FI (p=0.047) at 1 year for appearance of soft-tissue and satisfaction with colour. There were no differences for self-consciousness, smile and pain/discomfort while eating/hard food items. CONCLUSIONS: Although participants tended to rate the health of mucosa around PS implants as slighty better than the other two implant systems, the differences were minimal and inconsistent. Thus, patient satisfaction in terms self-perceived gingival health and esthetics was high for all 3 systems tested, suggesting that patients are unable to detect mucosal inflammation. CLINICAL SIGNIFICANCE: Patients find it difficult to perceive mucosal inflammation; hence, it is recommended that patients attend implant follow-up visits, even if they do not perceive inflammation. The study suggests that there is a relationship between the PROs and the clinical outcomes of tested implants.

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OBJECTIVE: To evaluate the performance of the indirect technique in peri-implant soft tissue contour duplication after the delivery procedure in the anterior maxilla. MATERIALS AND METHODS: Patients with single implant-supported fixed restorations in the anterior maxilla were recruited. For the impression procedure, an intraoral scan was acquired by both the direct and the indirect techniques. For the delivery procedure, implants were randomly allocated into one of the two groups according to the approaches of digital impression preceding definite crown fabrication (A-direct technique; B-indirect technique) and were scanned again after the definite crown delivery. The stereolithography files were superimposed to analyze changes in peri-implant soft tissue contour after the delivery procedure. The main outcomes were dimensional deviations of peri-implant mucosa, and the secondary outcome was differences in the pink esthetic score (PES). RESULTS: A total of 20 implants that underwent the complete workflow were included. After the delivery procedure, significant deviations in palatal tissue thickness between the provisional and definite crowns were observed in Group A but these were absent in Group B. Additionally, deviations in labial thickness (0.27 ± 0.12 mm vs. 0.08 ± 0.09 mm) and palatal thickness (0.17 ± 0.15 mm vs. 0.03 ± 0.08 mm), and labial volume of soft tissue (1.87 ± 0.94 mm3 vs. 0.75 ± 0.74 mm3 ) in Group A were significantly higher than those in Group B. No significant differences in PES were found. CONCLUSION: The indirect technique of scanning the provisional crown can more accurately duplicate the peri-implant soft tissue contour than the direct technique, resulting in a smaller deviation of the soft tissue in the delivery procedure.

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PURPOSE: The aim of the present study was to evaluate the long-term effectiveness of a xenogeneic collagen matrix (CM) in pre-prosthetic augmentation of the keratinized mucosa width (KMW) at implant sites. METHODS: All of the patients with localized implant-supported rehabilitation previously treated with vestibuloplasty and KMW augmentation with a non-cross-linked porcine CM were recalled. KMW was measured clinically in an apico-coronal direction from the mucogingival junction to the mucosal margin at the prosthetic zenith of each crown. Measurements were performed clinically by means of a PCP-UNC15 periodontal probe and rounded to the nearest mm. KMW values recorded at 1 year, 5 and 10 years from the soft tissue augmentation procedure were compared using a one-way repeated-measures ANOVA with Bonferroni multiple comparison post-hoc analysis. The level of significance was set at 0.05. RESULTS: Measurements were conducted on 13 patients. All implants were in function with no signs of biological complications. All except one implant site showed KMW ≥ 2 mm. KMW decreased significantly from 1 year (3.33 ± 1.11 mm) to 5 years (2.77 ± 0.92 mm) (p = 0.001), and finally remained stable from 5 to 10 years (3.2 ± 0.99 mm) (p = 0.607). From a visual aspect, peri-implant soft tissues were characterized by a good texture and color blending compared to the adjacent teeth, highlighting good integration of the remodeled tissues and stability of the esthetic result. CONCLUSIONS: The use of a CM in pre-prosthetic soft tissue augmentation at implant sites has proven to be effective in obtaining and maintaining at least 2 mm of KMW around dental implants over a follow-up of 10 years.

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The stability of peri-implant soft tissues is essential for long-term success. Integrins play a vital role in biological processes through developing and maintaining cell interactions; however, few studies have evaluated the effects of modifications to abutment surfaces on cell adhesion across integrin expression. Therefore, this pilot study assessed the influence of different surface topographies of titanium healing abutments prepared by additive manufacturing (AM) on the gene expression levels of the integrin subunits α2, ß1, αv, and ß6 in the human peri-implant mucosa. Thirteen healthy adults were included. Depending on the number of required implants, the subjects were distributed in different groups as a function of healing abutment topography: group 1 (fully rough surface); group 2 (upper machined + lower rough); group 3 (rough upper surface + lower machined); group 4 (fully machined). A total of 40 samples (n = 10/group) of the peri-implant mucosa around the abutments were collected 30 days after implant placement, and subsequently, the gene expression levels were evaluated using real-time PCR. The levels of gene expression of ß1-subunit integrin were upregulated for individuals receiving fully rough surface abutments compared with the other surface topographies (p < 0.05). However, the healing abutment topography did not affect the gene expression levels of the α2, αv, and ß6 integrin subunits in the human peri-implant mucosa (p > 0.05). This preliminary study suggested that controlled modifications of the surface topography of titanium healing abutments produced by AM may influence the quality of the peri-implant mucosa in the early stages of the soft tissue healing process.

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PURPOSE: To analyze the tissue morphology around implant-supported prostheses by digital technology and to evaluate the effect of prosthetic contours on the changes in tissues following the free gingiva graft procedure. MATERIAL AND METHODS: A total of 53 implants in 32 patients receiving free gingiva grafts were selected. These had previously presented insufficient keratinized mucosa width (KMW). At the follow-up visits (mean: 16.66 ± 9.97 months), the implant position and tissue condition were documented with an oral scanner. Vertical soft tissue thickness (VT), measured from the implant-abutment connection to the marginal tissues, and horizontal soft tissue thickness (HT), at the level of the platform, were calculated. The VT, HT, and emergence angle (EA) of prostheses were assessed by 3Shape analyzing software. The final KMW was measured by clinical assessment. Marginal bone loss (MBL) was calculated in the follow-up bitewing radiographs. RESULTS: The mean VT in the study was 2.65 ± 0.75 mm at the mid-buccal sites, 3.74 ± 1.22 mm at the mesial, 3.16 ± 1.08 mm at the distal, and 2.53 ± 0.92 at the mid-lingual aspects. The mid-buccal HT was 1.45 ± 0.53 mm while the mid-lingual was 1.05 ± 0.43 mm (p = 0.008). Interestingly, prostheses with mid-buccal EA > $\; > \;$ 30° exhibited slightly lower VT, but higher HT, than the ones with EA ≤ $\; \le \;$ 30°. Prostheses with proximal EA > 30° displayed slightly more MBL, compared to prostheses with EA ≤ $\; \le \;$ 30°. The mean KMW was 4.08 ± 1.10 mm. CONCLUSIONS: Free gingival grafting is a predictable treatment approach to augmenting soft tissue 3-dimensionally. Prostheses with EA ≤ $\; \le \;$ 30° were preferable for preserving the maximal VT and maintaining crestal bone stability.

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AIM: The aetiology and pathogenesis of peri-implantitis are currently under active research. This study aimed to dissect the pathogenesis of murine experimental peri-implantitis and assess Resolvin D2 (RvD2) as a new treatment modality. MATERIALS AND METHODS: Four weeks following titanium implant insertion, mice were infected with Porphyromonas gingivalis using single or multiple oral lavages. RvD2 was administrated following infection, and tissues were analysed using flow cytometry, quantitative RT-PCR, taxonomic profiling, and micro-computed tomography. RESULTS: Repeated infections with Pg resulted in microbial dysbiosis and a higher influx of innate and adaptive leukocytes to the peri-implant mucosa (PIM) than to gingiva surrounding the teeth. This was accompanied by increased expression levels of IFN-α, IL-1ß, and RANKL\OPG ratio. Interestingly, whereas repetitive infections resulted in bone loss around implants and teeth, a single infection induced bone loss only around implants, suggesting a higher susceptibility of the implants to infection. Treatment with RvD2 prevented Pg-driven bone loss and reduced leukocyte infiltration to the PIM. CONCLUSIONS: Murine dental implants are associated with dysregulated local immunity and increase susceptibility to pathogen-induced peri-implantitis. However, the disease can be prevented by RvD2 treatment, highlighting the promising therapeutic potential of this treatment modality.

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OBJECTIVES: The aim of this study was to comprehensively assess the literature in terms of the effect of peri-implant mucosal thickness on esthetic outcomes and the efficacy of soft tissue augmentation procedures to increase the mucosal thickness with autogenous grafts or soft tissue substitutes. MATERIAL AND METHODS: Two systematic reviews (SR) were performed prior to the consensus meeting to assess the following questions. Review 1, focused question: In systemically healthy patients with an implant-supported fixed prosthesis, what is the influence of thin as compared to thick peri-implant mucosa on esthetic outcomes? Review 2, focused question 1: In systemically healthy humans with at least one dental implant (immediate or staged implant), what is the efficacy of connective tissue graft (CTG), as compared to absence of a soft tissue grafting procedure, in terms of gain in peri-implant soft tissue thickness (STT) reported by randomized controlled clinical trials (RCTs) or controlled clinical trials (CCTs)? Review 2, focused question 2: In systemically healthy humans with at least one dental implant (immediate or staged implant), what is the efficacy of CTG, as compared to soft tissue substitutes, in terms of gain in peri-implant STT reported by RCTs or CCTs? The outcomes of the two SRs, the consensus statements, the clinical implications, and the research recommendations were discussed and subsequently approved at the consensus meeting during the group and plenary sessions. CONCLUSIONS: There was a tendency of superior esthetic outcomes in the presence of a thick mucosa. The connective tissue graft remains the standard of care in terms of increasing mucosa thickness.

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AIMS: The objective of the present case series is to report on the rationale, surgical technique and outcome of a protocol for peri-implant mucosal phenotype modification therapy, referred to as "fibrin immobilization vestibular extension (FIVE)". MATERIAL AND METHODS: The protocol utilized entailed apical positioning and stabilization of peri-implant flap with modular screws. The screws were also used for the immobilization of solid matrix platelet-rich fibrin to fill the gap created between apically positioned flap and the crestal margin of the flap. RESULTS: A total of 30 patients (12 male, 18 females) with 93 implants were treated with FIVE protocol for various indications, including for vestibular extension following alveolar ridge augmentation (N = 6), preprosthetic (N = 9), postprosthetic (N = 2), and peri-implantitis (N = 13). The keratinized mucosal width preoperatively was 1.67 mm with 95% confidence interval [CI] (1.46, 1.88). Immediately following FIVE surgery, the vestibule was extended to 9.10 with 95% CI (8.44, 9.76). At 3 months, 4.9 mm (95% CI: 4.5-5.2 mm) of peri-implant keratinized mucosal width was present. The keratinized mucosal width remained relatively stable thereafter and was 4.0 mm (95% CI: 3.5-4.5 mm) at 3 years post-FIVE surgery. When overall group means across all time points were analyzed, maxilla had mean of 6.1 mm (95% CI: 5.8-6.5) versus mandible exhibited mean of 5.1 mm (95% CI: 4.6-5.6 mm). The mean of maxilla was significantly higher than that of the mandible (p < 0.0001) across all time points. Treatment of peri-implantitis with FIVE lead to significant pocket reduction and wide band of keratinized mucosa. Seven of 38 implants in 3 of 13 peri-implantitis patients were removed due to advanced peri-implantitis. DISCUSSION: The present case series provides proof-of-principle data for efficacy of FIVE for peri-implant phenotype modification therapy that generated attached keratinized mucosa in a variety of applications. This protocol provides an alternative to procedures involving harvesting of autogenous mucosal graft.

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The management and prevention of soft tissue complications is of key importance in modern implant dentistry and influences biologic and esthetic outcomes. The assessment of the soft tissue conditions from a quantitative and qualitative perspective should, therefore, be part of the overall treatment plan. Such an assessment dictates a potential indication as well as an ideal time point for additional soft tissue management. A proper risk assessment and management of the soft tissues at the planned implant site are of key importance prior to any implant-related surgery. Cases with peri-implant soft tissue complications generally involve: (a) a lack of attached and keratinized mucosa; (b) insufficient volume; (c) development of mucosal dehiscences; or (d) a combination of (a), (b), and (c). In case of soft tissue deficiencies, these should be addressed as early as possible to increase the predictability of the surgical interventions. This article reviews the main causes for peri-implant soft tissue complications and presents different therapeutic options for the management of various clinical scenarios.

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INTRODUCTION: A special interest has been raised regarding the role of the peri-implant mucosa as a critical factor for long-term maintenance of the artificial fixtures as well as the final esthetic outcome that may significantly affect patient satisfaction. It is then imperative to develop minimally invasive and easy-to-apply plastic surgical methods to increase the volume of the peri-implant mucosa. CASE PRESENTATION: The limited scientific evidence regarding possible techniques to treat esthetic soft tissue defects around endosseous implants is encouraging a preventive soft tissue augmentation of mucosa deficiencies and thin phenotypes. Several techniques have been proposed to augment the volume of the mucosa to achieve the so-called pink esthetics. Among these the buccal pedicle flap seems to be less invasive in terms of morbidity since it does not necessitate any soft tissue harvesting. Its low morbidity allows it to treat patients without the need of postoperative medications since it reduces pain, the risk of infections, alteration of the sensitivity of the donor site and significantly reduces the period of healing which is generally longer when associated with connective tissue grafts. A modified surgical approach is based on the combination of the buccal pedicle flap with a stable collagen matrix to boost a biomimetic peri-implant mucosa and generate a convex pink interface with the final restoration. CONCLUSION: The proposed modified buccal pedicle flap seems to be promising in terms of decreased morbidity and maintenance of the blood supply, and conducive to an increased patient acceptance rate.

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BACKGROUND: The vertical thickness of the peri-implant mucosa is associated with the amount of post treatment marginal bone loss. However, the variations in mucosal thickness at the different edentulous sites have been sparsely documented. The purpose of the study was to conduct a survey of the frequency distribution of variations in mucosal thickness at the different sites of the edentulous alveolar ridge and to compare them according to gender. Our study included 125 partially edentulous patients having a total of 296 implant sites. Cone-beam computed tomography (CBCT) scans were obtained by placing a diagnostic template with a radiopaque crown indicator on the ridge to determine the mucosal thickness at the crest of the alveolar ridge. RESULTS: The mucosal thickness was 3.0±1.3 mm in the maxilla, which was significantly greater than the mucosal thickness of 2.0±1.0 mm in the mandible (p<0.001). In both the maxilla and the mandible, the mucosa was the thickest in the anterior region, followed by the premolar and molar regions. Sites were further classified into two groups based on whether the mucosal thickness was greater than 2 mm. In the mandible, more than half of the sites showed a mucosal thickness of 2 mm or less. CONCLUSIONS: Although this study was a limited preoperative study, the vertical mucosal thickness at the edentulous ridge differed between the maxillary and mandibular regions. The majority of sites in the mandibular molar region had a mucosal thickness of less than 2 mm. Practitioners might be able to develop an optimal dental implant treatment plan for long-term biologic and esthetic stability by considering these factors.

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OBJECTIVES: The aim of the present retrospective study was to evaluate papillae filling rate and buccal margins coronal growth in implant-supported prostheses which were over-contoured at the apical buccal third to form a rearmost collar zone, thus mimicking a false root. MATERIAL AND METHODS: The influence of adjacent elements, teeth, implants, or pontics was examined. One-hundred and three crowns have been assessed in photographs taken on 61 patients after prosthesis delivering and at last follow-up (mean 2.8 years). The Jemt index was adopted to evaluate papillae growth at the baseline and follow-up as follows: 0, absence of papilla; 1, less than half of interdental embrasure height; 2, more than half of interdental embrasure height; 3, fully papilla filled interdental embrasure. Index score 4, papilla hyperplasia was not included. Moreover, the coronal growth (or recession) of buccal mucosa in implant-supported crowns was assessed. RESULTS: At baseline, a total of 29 papillae had a 0 score, while only two scored 3 with complete papilla formation. On follow-up, only one papilla scored 0, while 46 scored 3 with complete interdental embrasures filling. The highest papilla score was registered from first year crown insertion and likewise in interdental embrasures located between two implants or implants and pontics. Moreover, the buccal margin growth was observed in almost 80% of crowns. Such findings seem to indicate that buccal margin and papilla around implant-supported crowns presented a coronal growth over time, especially during its first year. The average papilla growth between two implants was no lower than that observed in papilla present between implants and natural teeth. CONCLUSIONS: Recessed areas at collar of implant-supported prostheses appear to positively influence papillae and buccal margin growth, especially in its first year. Papilla growth between two implants was similar to that observed between implants and natural teeth.

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Human gingival epithelial cells (HGEps) and fibroblasts (HGFs) are the main cell types in peri-implant soft tissue. HGEps are constantly exposed to bacteria, but HGFs are protected by connective tissue as long as the mucosa-implant seal is intact. Streptococcus oralis is one of the commensal bacteria, is highly abundant at healthy implant sites, and might modulate soft tissue cells-as has been described for other streptococci. We have therefore investigated the effects of the S. oralis biofilm on HGEps and HGFs. HGEps or HGFs were grown separately on titanium disks and responded to challenge with S. oralis biofilm. HGFs were severely damaged after 4 h, exhibiting transcriptional inflammatory and stress responses. In contrast, challenge with S. oralis only induced a mild transcriptional inflammatory response in HGEps, without cellular damage. HGFs were more susceptible to the S. oralis biofilm than HGEps. The pro-inflammatory interleukin 6 (IL-6) was attenuated in HGFs, as was interleukin 8 (CXCL8) in HGEps. This indicates that S. oralis can actively protect tissue. In conclusion, commensal biofilms can promote homeostatic tissue protection, but only if the implant-mucosa interface is intact and HGFs are not directly exposed.

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Oral mucosal homeostasis is achieved by complex immunologic mechanisms, orchestrating host immunity to adapt to the physiologic functions of the various specialized niches in the oral cavity. Dental implants introduce a novel mucosal niche to the immune system to deal with. Nevertheless, the immune mechanisms engaged toward implants and whether they have broader effects are not well defined. Using a murine model, we found an accumulation of neutrophils and RANKL-expressing T and B lymphocytes in the implant-surrounding mucosa, accompanied by local bone loss. Surprisingly, the presence of implants had an impact on remote periodontal sites, as elevated inflammation and accelerated bone loss were detected in intact distant teeth. This was due to microbial dysbiosis induced by the implants, since antibiotic treatment prevented bone loss around teeth. However, antibiotic treatment failed to prevent the loss of implant-supporting bone, highlighting the distinct mechanisms mediating bone loss at each site. Further analysis revealed that implants induced chronic lymphocyte activation and increased mRNA expression of IFN-α and accumulation of IFN-α-producing plasmacytoid dendritic cells, which we previously reported as bone-destructive immune responses. Collectively, this study demonstrates that implants have a strong and broad impact on oral mucosal homeostasis, inducing periodontal bone loss in a niche-specific manner that is both microbiota dependent and independent.

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