Books

This study evaluated the impact of soft tissue grafts to reduce marginal periimplant recession (MPR) after 1 year of follow-up. A total of 24 patients with one single failing maxillary incisor presenting facial bone dehiscence and receiving an immediate implant, bone graft, and provisional were randomly divided into three groups (n = 8 in each group): control (CTL), collagen matrix (CM), and connective tissue graft (CTG). Clinical, photographic, and tomographic analyses were performed to evaluate tissue alterations. The use of a CTG avoided MPR (P < .05) and provided better contour of the alveolar ridge (P < .01) and greater thickness (P < .05) of the soft tissue at the implant facial aspect.

Purpose: The All-on-4 treatment concept has been shown to be an effective clinical procedure; however, to date, no studies have analyzed the subgingival microbiota present in these restorations. The purpose of this study was to evaluate the microbial profile of the subgingival biofilm around dental implants placed in the All-on-4 protocol and compare the microbial profile around axial and tilted implants. Materials and Methods: Fourteen subjects treated by the All-on-4 concept were evaluated clinically and microbiologically. Subgingival biofilm was collected from each patient, and the amount of 40 species of bacteria was assessed using the checkerboard DNA-DNA hybridization technique. Results: The results for the indices of probing depth (PD), bleeding on probing, marginal bleeding, and visible plaque were 2.32 mm, 46%, 60%, and 57%, respectively. Tilted implants presented a significantly higher mean PD and Plaque Index compared with axial implants (P < .05). Fusobacterium nucleatum ssp vincentii, Veillonella parvula, and Fusobacterium nucleatum ssp polymorphum were found in higher levels; however, no difference in the microbial composition was observed between tilted and axial implants (P > .05). Tilted implants presented statistically higher mean levels for the orange complex in relation to the axial implants (P < .05). Conclusion: Despite the clinical success rate of the All-on-4 protocol, the subgingival biofilm of tilted implants presented a higher proportion for the orange complex pathogens in comparison to axial implants. These data could suggest that subjects with this modality of implant-supported restoration must be aware that they need a more rigorous maintenance protocol. Keywords: All-on-4, dental implant, microbiota, prosthesis, subgingival biofilm

Purpose: The objective of this investigation was to assess the microbiologic contamination in the inner surface of titanium implants prior to prosthetic abutment placement. Materials and Methods: The study population consisted of partially edentulous individuals who had previously received at least one internal hexagon titanium dental implant. A bacterial sample of the inner surface of the individual dental implant was taken after surgical reopening for healing abutment placement. The samples were allocated in order to evaluate three distinctive variables as follows: (1) location (mandible vs maxilla), (2) early exposure of implants to the oral cavity (cover screw) throughout the healing stage (exposed vs not exposed), and (3) existence or lack of keratinized mucosa (KM). The microorganism species detected were examined by checkerboard DNA-DNA hybridization. Results: A total of 32 partially edentulous patients with 78 implants placed in both the maxilla and mandible were enrolled: 8 men and 24 women, ranging in age from 27 to 64 years (mean age: 47.7 years). Bacteria were detected in 20 patients, distributed in 41 implants. Spontaneous early implant exposure and absence of KM did not increase bacterial contamination in the inner surface of implants. A significant increase in the detection of 22 bacterial species was found in the mandible when compared with the maxilla. Conclusion: Microbial biofilm accumulation in the implant's internal surface might happen before healing abutment placement. Exposure of implants to the oral cavity and absence of KM were not directly related to a greater microbial biofilm count. The results suggested that submerged healing does not protect implants against bacterial colonization. Keywords: checkerboard DNA-DNA hybridization, dental implants, microbiology, peri-implantitis

Purpose: To evaluate the gene expression levels of semaphorins 3A, 3B, 4A, and 4D in both healthy and diseased implants. Materials and Methods: Subjects with peri-implantitis presented clinical attachment loss, probing depth ≥ 5 mm, bleeding on probing and/or suppuration, and radiographic bone loss > 4 mm. Peri-implant tissue biopsy specimens were sampled for analysis of the mRNA expression levels for semaphorins 3A, 3B, 4A, and 4D. A real-time polymerase chain reaction was performed, and the gene expression levels of semaphorins in relation to the housekeeping gene were analyzed by using the nonparametric Mann-Whitney test (P < .05). Results: Thirty-five subjects (16 men, 19 women; mean age: 54.12 ± 2.34 years) with implant-supported restorations, using screw-shaped dental implants with internal or external hexagon were enrolled in this study. Higher levels of semaphorins 3A and 4D were detected in the peri-implantitis compared with the healthy tissues (P = .0011 and P = .0404, respectively), whereas Sem4A levels were significantly higher in the control group (P < .0001). Differences between groups in the expression levels of Sem3B were not significant. Conclusion: Advanced peri-implantitis lesions showed higher levels of gene expression for Sem3A and Sem4D and lower levels of Sem4A in comparison to tissues obtained from a healthy dental implant. Keywords: dental implants, gene expression, peri-implantitis, real-time PCR, semaphorins

Purpose: The aim of this in vitro study was to assess the resistance to static fatigue of implants with different connections before and after implantoplasty. Materials and Methods: Sixty conical implants and 60 abutments were used; 4-mm-diameter versions were available for each model. Three groups (n = 20) were established based on the following implant connections: external hexagon (group 1), internal hexagon (group 2), and Morse taper (group 3). The implants of each group were submitted to a compressive load before (n = 10) and after the implantoplasty (n = 10). The wear was performed in a mechanical lathe machine using a carbide bur, and the final dimensions of each sample were measured. All groups were subjected to quasi-static loading at a 30-degree angle to the implant axis in a universal testing machine and 5 mm out of the implant support. Results: After the implantoplasty, the mean final diameter was 3.13 ± 0.033 mm for group 1, 3.23 ± 0.023 mm for group 2, and 3.25 ± 0.03 mm for group 3. The mean fracture strengths for the groups before and after the implantoplasty were, respectively, 773.1 ± 13.16 N and 487.1 ± 93.72 N in group 1; 829.4 ± 14.12 N and 495.7 ± 85.24 N in group 2; and 898.1 ± 19.25 N and 717.6 ± 77.25 N in group 3. Conclusion: Resistance to loading decreased significantly after implantoplasty, and varied among the three implant connection designs. Keywords: dental implant, fracture mode, fracture strength, implant connection, implantoplasty

Purpose: The aim of this prospective controlled study was to evaluate the influence of osteopenia on the levels of osteoclastogenesis-related factors in the peri-implant crevicular fluid (PICF) and on the clinical parameters of immediately loaded implants. Materials and Methods: This study included 24 patients who received at least two implants in the mandible, with restorations delivered 48 hours after implant placement. Patients were divided into control (n = 11) and osteopenia (n = 13) groups. Seven days after implant placement (baseline) and 4 months after implant placement, PICF samples were obtained, and clinical parameters (Plaque Index, Gingival Index, bleeding on probing, suppuration, probing depths, clinical attachment levels) were measured. A commercially available enzyme-linked immunosorbent assay was used to analyze PICF samples for levels of soluble receptor activator of nuclear factor of κB ligand (sRANKL) and osteoprotegerin (OPG). At the 4-month follow-up visit, the implant-supported restorations were removed and periapical radiographs were acquired to evaluate bone loss around the implants. Results: Eighty-eight immediately loaded implants were included in this study (38 in the control group, 50 in the osteopenia group). The RANKL and OPG levels, the RANKL/OPG ratio, and the clinical parameters were similar between the groups at both time points. However, the levels of these factors in PICF differed significantly between baseline and 4 months after surgery. Conclusion: Within the limitations of this short-term study, it can be concluded that osteopenia does not influence the PICF levels of osteoclastogenesis-related factors in immediately loaded implants after 4 months of loading. Keywords: dental implants, dental implant loading, immediate loading, osteopenia, osteoporosis, osteoprotegerin, RANK ligand, receptor activator of nuclear factor-kappa B

The aim of this study was to histomorphometrically assess the soft tissue anatomy in single gingival recessions (GR) treated with a laterally positioned flap (LPF). Five patients presenting maxillary first molars with GR to the apex of the buccal surface of the mesial-buccal root were invited to take part. The LPF-treated roots were removed en bloc (the root and the soft tissue covering the treated GR) 3 to 4 months postoperatively. Photomicrographs of Mallory trichrome stain sections were taken to allow reassessment of the specimens regarding the longitudinal dimensions of the crevicular/sulcular and junctional epithelia. The use of LPF resulted in new attachment with formation of crevicular epithelium, long junctional epithelium, and some connective tissue, re-establishing the normal anatomical characteristics of the soft tissues covering the previously exposed root.

This study assessed the use of orthodontic extrusion (OE) for biologic width reestablishment (BWR) and compared two protocols for BWR: periodontal flap surgery (FS) performed either before (FS + OE) or after (OE + FS) extrusion. Databases were screened up to March 2013 for studies on OE, and outcomes from 13 patients treated by OE + FS or FS + OE were assessed. The results of the literature showed that OE + fiberotomy led to a greater amount of root extrusion than OE alone. The clinical/radiographic assessment demonstrated no significant differences between groups (P > .05). Within groups, there was an improvement in the keratinized tissue (P = .034) and in probing depth (P = .025) for OE + FS.

The aim of this case series was a clinical, histologic, and histomorphometric evaluation of calcium carbonate in sinus elevation procedures. Sinus augmentation was performed in the atrophic maxillae of 24 subjects using calcium carbonate. Six months after the regeneration procedures, 68 implants were placed and clinically followed for 1 to 5 years, depending on the placement timing. At the last implant placement procedure, 8 bone cores were harvested and processed for histology. After a 6-month healing period, sinuses grafted with calcium carbonate showed a mean vertical bone gain of 6.93 ± 0.23 mm. The histomorphometric analysis revealed 15% ± 3% residual grafted biomaterial, 28% ± 2% newly formed bone, and 57% ± 2% marrow spaces. The implant survival rate was 98.5%. It can be concluded that calcium carbonate was shown to be clinically suitable for sinus elevation procedures after 1 to 5 years of follow-up and histologically biocompatible and osteoconductive. (Int J Periodontics Restorative Dent 2014;34:e43- e49. doi: 10.11607/prd.1832)

Purpose: This study compared the loosening torque of experimental conical-head abutment screws to that of conventional flat-head screws of implants with external-hex (EH) and internal tri-channel (IT) connections before and after mechanical loading. Materials and Methods: Forty-four implant/screw/abutment assemblies were divided into four groups: EH/flat-head screw (EH), IT/flat-head screw (IT), EH/conical-head screw (EHCS), and IT/conical-head screw (ITCS). Three assemblies from each group were analyzed in a stereoscopic magnifier and then returned to their respective groups. One assembly was removed from each group and transversely sectioned for optical microscopy analysis. Abutments were tightened at 32 Ncm of torque; after 10 minutes, loosening torque was measured. The same abutments were then retightened with 32 Ncm of torque; after 10 minutes, they were mechanically loaded for 300,000 cycles and loosening torque was again measured. Data were collected and an exploratory analysis was performed. Comparisons were made by orthogonal contrasts using a linear mixed effects model (random and fixed effects). Results: Comparisons before mechanical cycling showed significant differences between groups except for EH vs IT and EHCS vs ITCS. After mechanical cycling, only the comparisons EH vs IT and EHCS vs ITCS showed no significant differences. Considering the same group, before and after mechanical cycling, all comparisons showed significant differences. Conclusions: The shape of the abutment screw head significantly influenced loosening torque: conical-head screws showed higher loosening torque values than conventional flat-head screws before and after loading. The implant/abutment connection design exerted no significant influence on loosening torque.