Background: Peri-implant tissue condition can result from prosthodontic, surgical and bacteriological factors. Purpose: This study investigated the effects of prosthodontic factors on peri-implant tissue. Materials and Methods: Subjects were 140 patients with 310 implants from Osaka University Dental Hospital. Prosthodontic factors examined were the connection type, the suprastructure retention type, the material of the abutment and the mesiodistal and buccolingual prosthetic form of the superstructure as emergence angle. The objective variables were the modified bleeding index (mBI) and marginal bone level (MBL). Statistical analysis was used as a generalized estimation equation. Results: The taper joint had a significantly smaller MBL than the butt joint (P < .001). There was no significant difference in mBI and MBL between cement and screw retaining. Zirconium and titanium resulted in a significantly smaller mBI than gold alloy (zirconium/gold alloy: P = .037, titanium / gold alloy: P = .021), but there was no significant difference in the MBL. Both mBI and MBL tended to be smaller when the emergence angle was around 20 to 40 , although this difference was not significant. Conclusion: As a result of multivariate analysis, our findings suggest that to reduce MBL from the perspective of prosthodontic factors it is preferable to use an implant with a taper joint connection positioned with an emergence angle of 20 to 40 .

Background There is no clear evidence that immediate implant placement can be applied to cases with dehiscence in the facial alveolar bone prior to extraction. Purpose To evaluate the results of immediate implant placement in the anterior maxilla with facial alveolar bone dehiscence. Materials and Methods We super positioned pre‐ and post‐operative cone‐beam computed tomography (CBCT) three‐dimensional reconstruction images. A CBCT was taken before tooth extraction (T0), when the definitive restoration was placed (T1), and 1 year after placing the definitive restoration (T2). The depth and width of the dehiscence at T0, and the height and width of the facial hard and soft tissues are measured at the implant site at T1 and T2. We calculated the change in the amount of hard and soft tissues from T1 to T2 and determined the correlation between preoperative facial alveolar bone morphology and postoperative gingival recession. Results 13 women and 7 men were recruited. A total of 20 implants were evaluated. The implant survival rate was 100%. The mean facial alveolar bone dehiscence width was 3.9 ± 1.6 mm, and the mean depth from platform level was 2.9 ± 1.7 mm. The mean implant body exposure on the buccal was 4.8 ± 1.7 mm, and the mean socket width gap was 2.1 ± 0.8 mm. At T1, the mean facial hard tissue width was 2.1 ± 0.7 mm, and the mean height was 2.0 ± 0.7 mm. The mean change in vertical gingival recession from T1 to T2 was 0.5 ± 0.5 mm. We found a positive correlation between facial alveolar bone dehiscence width and gingival recession (r = 0.46, p‐value = 0.04) and between dehiscence depth and gingival recession (r = 0.48, p‐value = 0.03). Conclusions The results of our CBCT superposition method indicated that immediate implant placement can be considered in patients with facial alveolar bone dehiscence. However, there may be a higher risk of gingival recession with wide or deep dehiscence.

Background Immediate implant placement with simultaneous contour augmentation such as guided bone regeneration (GBR) or connective tissue grafting (CTG) has been widely performed. However, few prospective studies have evaluated both peri-implant bone and soft tissue changes between the preoperative and postoperative periods. The purpose of this study is to quantify the horizontal dimensional changes of the facial bone and soft tissue following immediate implant placement with contour augmentation. Material and methods Twenty patients who underwent immediate implant placement in the anterior maxilla received GBR and CTG (test group) or GBR only (control group). Cone-beam computed tomography (CBCT) scans were taken preoperatively and 1 year after the definitive prosthesis connection, and then, they were superimposed. On the CBCT images of the two stages, the horizontal distance from the implant platform to the facial bone surface (BW) and the horizontal soft tissue width (GW) were measured at the implant platform level and 2 mm apical to the implant platform level. The sum of BW and GW (=TW) was used to assess the facial mucosal contour. Results BW decreased significantly from preoperative to 1 year after prosthesis connection with a mean decrease of 0.47 mm (P =0.021) in the control group and a mean decrease of 0.50 mm (P = 0.019) in the test group at the implant platform level. GW increased significantly with a mean increase of 1.37 mm (P =0.005) in the test group at the implant platform level. TW decreased significantly with a mean decrease of 0.46 mm in the control group (P =0.049) but increased significantly with a mean increase of 0.87 mm in the test group (P =0.005) at the implant platform level. Conclusions Immediate implant placement with CTG showed a soft tissue gain of 1.37 mm compensated for bone resorption, thus still preserving the preoperative mucosal contour. CTG should be performed with immediate implant placement in cases where preoperative mucosal contours need to be maintained.

Maintaining peri-implant tissue health is necessary for the longterm success of implant treatment. Poor oral hygiene, smoking, and a history of periodontal disease have been reported as risk factors for peri-implantitis [1].Previous research has discussed whether the presence of keratinized mucosa (KM) is required to keep peri-implant tissue healthy [2].Peri-implant tissue health requires no clinical signs of inflammation, no bleeding and suppuration on gentle probing, no increase in probing depth compared with previous examinations, and no bone loss beyond crestal bone level changes resulting from initial bone remodeling [3]. Some evidence suggests implants with less than 2 mm of KM exhibit more bleeding on probing and supporting bone loss than those with more than 2 mm of KM [4]. Conversely, Roccuzzo et al. found that peri-implant tissue health could be maintained with good oral hygiene in spite of the width of KM [5]. It is important, therefore, to confirm the influence of KM on peri-implant tissue health. If the presence of KM is important for peri-implant tissue health, soft tissue grafting may be considered in cases with insufficient KM. Although many studies have investigated the influence of KM, a clear conclusion has not yet been reached.One of the difficulties in reaching a consensus is the presence of confounders such as poor oral hygiene, smoking, and a history of periodontal disease in previous studies. Most previous studies did not consider factors affecting peri-implant tissue health that prevent accurate assessment of the effect of KM.The purpose of our cross-sectional study was to confirm the association between peri-implant tissue health and the presence of KM using multivariate analysis to control for the confounding effects. We hypothesize that the presence of ≥ 2 mm of KM is related to improved peri-implant tissue health when compared with KM that is < 2 mm wide.We built up the null hypothesis that the presence of ≥ 2 mm of KM is not related to improved peri-implant tissue health when compared with KM that is < 2 mm wide.