Trabecular Bone Assessment Using Magnetic-Resonance Imaging: A Pilot Study.

The aim of this study was to assess trabecular bone morphology via magnetic-resonance imaging (MRI) using microcomputed tomography (µCT) as the control group. Porcine bone samples were scanned with T1-weighted turbo spin echo sequence imaging, using TR 25 ms, TE 3.5 ms, FOV 100 × 100 × 90, voxel size 0.22 × 0.22 × 0.50 mm, and scan time of 11:18. µCT was used as the control group with 80 kV, 125 mA, and a voxel size of 16 µm. The trabecular bone was segmented on the basis of a reference threshold value and morphological parameters. Bone volume (BV), Bone-volume fraction (BvTv), Bone specific surface (BsBv), trabecular thickness (TbTh), and trabecular separation (TbSp) were evaluated. Paired t-test and Pearson correlation test were performed at p = 0.05. MRI overestimated BV, BvTv, TbTh, and TbSp values. BsBv was the only parameter that was underestimated by MRI. High statistical correlation (r = 0.826; p < 0.05) was found for BV measurements. Within the limitations of this study, MRI overestimated trabecular bone parameters, but with a statistically significant fixed linear offset.

Magnetic resonance imaging artifacts produced by dental implants with different geometries.

OBJECTIVES: The purpose of this study was to evaluate the MRI-artifact pattern produced by titanium and zirconia dental implants with different geometries (diameter and height). METHODS: Three titanium (Titan SLA, Straumann) and three zirconia (Pure Ceramic Implant, Straumann) dental implants differing on their design (diameter x height) were installed in porcine bone samples. Samples were scanned with a MRI (3T, T1W turbo spin echo sequence, TR/TE 25/3.5ms, voxel size 0.22×0.22×0.50 mm, scan time 11:18). Micro-CT was used as control group (80kV, 125mA, voxel size 16µm). Artifacts' distribution was measured at vestibular and lingual sites, mesial and distal sites, and at the apex. Statistical analysis was performed with Within-ANOVA (p=0.05). RESULTS: Artifacts distribution measured 2.57 ± 1.09 mm for titanium artifacts and 0.37 ± 0.20 mm for zirconia artifacts (p<0.05). Neither the measured sites (p=0.73) nor the implant geometries (p=0.43) influenced the appearance of artifacts. CONCLUSION: Artifacts were higher for titanium than zirconia implants. The artifacts pattern was similar for different dental implant geometries.

Efficacy of a Polyglycol Dimethacrylate-Based Adhesive in Sealing the Implant-Abutment Interface.

PURPOSE: The purpose of this study was to assess the effectiveness of a polyglycol dimethacrylate-based adhesive in preventing bacterial leakage through implant-abutment interfaces (IAIs). MATERIALS AND METHODS: After implant installation, the adhesive was applied in the experimental group (n = 10). None was applied in the control group (n = 10). Samples were collected from the inner walls of implants on days 0 and 90. The real-time polymerase chain reaction was used to detect bacterial DNA. RESULTS: All samples from the control group, versus 30% from the experimental group, harbored bacterial DNA on day 90. CONCLUSIONS: This polyglycol dimethacrylate-based adhesive may be used to seal the IAI. Further studies are warranted to verify its effectiveness over longer time periods.

Assessment of Buccal Bone Surrounding Dental Implants Using a High-Frequency Ultrasound Scanner.

The purpose of this study was to determine the buccal bone dimensions surrounding dental implants using a high-frequency ultrasound (US) scanner and cone-beam computed tomography (CBCT). Dental implants (n = 10) inserted in the maxilla of dry skulls were scanned using US (28 MHz, bandwidth 84%, aperture 6 mm, focal depth 13.2 mm) and CBCT (70 kV, 6.3 mA, voxel size 0.18 mm). The bone level and buccal bone thickness were determined on the buccal-lingual diameter of the implant. As a control group, the evaluated site was represented by a stone block containing the dental implant, and measurements were performed using an optical microscope. Statistical analysis was performed using a mixed linear regression model at a significance level of p < 0.05. There was no statistical difference among groups for the two measurements. For ultrasound, the mean discrepancy was 0.38 mm for bone thickness and 0.68 mm for bone level. For CBCT, the mean discrepancy was 0.51 mm for bone thickness and 0.09 mm for bone level. High-frequency ultrasound was able to measure buccal bone dimensions surrounding dental implants.

Accuracy of High-Frequency Ultrasound Scanner in Detecting Peri-implant Bone Defects.

The purpose of this study was to assess the accuracy of high-frequency ultrasound (US) in the measurement of peri-implant bone defects in comparison with cone-beam computed tomography (CBCT) and micro-computed tomography (µCT). Bone defects were mechanically created around dental implants inserted into porcine ribs (n = 10). The bone samples were scanned by CBCT, µCT and US. Linear dimensions of the peri-implant defects were determined for supra-alveolar component, intra-bony component and width. The accuracy of measurements was evaluated with repeated-measures analysis of variance and the intra-class correlation coefficient at p ≤ 0.05. US underestimated the measurements for the supra-alveolar and intra-bony components in comparison to CBCT and µCT, and there were no statistically significant differences in the measurements of width. The intra-class correlation coefficient of US ranged from 0.96 to 0.98, whereas that for CBCT ranged from 0.77 to 0.97. US was accurate in measuring the width of peri-implant defects, although vertical measurements were underestimated by approximately 1 mm in comparison to those of CBCT and µCT.

Patient outcomes and procedure working time for digital versus conventional impressions: A systematic review.

STATEMENT OF PROBLEM: Limited evidence is available comparing digital versus conventional impressions from the point of view of patient preference. PURPOSE: The purpose of this systematic review was to identify and summarize the available literature related to patient-centered outcomes for digital versus conventional impression techniques. MATERIAL AND METHODS: The databases Medline, Cochrane, Science Direct, Scopus, and Embase were electronically searched and complemented by hand searches. All published papers available on the databases from 1955 to July 2016 were considered for title and abstract analysis. RESULTS: A total of 2943 articles were initially identified through database searches, of which only 5 met the inclusion criteria for qualitative analysis. Four studies comparing patient-reported outcome measures (PROMs) between conventional and digital impressions revealed that the digital technique was more comfortable and caused less anxiety and sensation of nausea. Only 1 study reported no difference between the techniques regardless of patient comfort. Two studies reported a shorter procedure for the conventional technique, whereas 3 studies reported a shorter procedure for the digital technique. CONCLUSIONS: A lack of clinical studies addressing patient outcomes regarding digital prosthodontic treatments was observed among the included articles. However, current evidence suggests that patients are more likely to prefer the digital workflow than the conventional techniques.

Influence of Abutment Surface Treatments on Screw Loosening of Morse Taper Implants.

PURPOSE: To evaluate the effect of blasting and bonding on abutment surface to prevent screw loosening in Morse taper connections. MATERIAL AND METHODS: Twenty-eight Morse taper connection implants were divided into 4 groups: no treatment (G1), blasting (G2), bonding (G3), and blasting + bonding (G4). In groups G2 and G4, the abutments were blasted with aluminum oxide granules; in groups G3 and G4, the conical abutment region was covered with a thin layer of bond thread lock agent. In all implants, the abutment-implant joint was tightened at a torque of 35 Ncm. The specimens were submitted to the mechanical cycling, under an oblique load for 1.0 × 10 cycles. The torque was measured with a digital torque meter. Data were analyzed by the t test, one-way analysis of variance, and Tukey tests (95%). RESULTS: The loosening strength was significantly higher in group G4 (35.83 ± 3.02 Ncm). There was no significant difference among groups G1 (25.86 ± 1.96 Ncm), G2 (25.86 ± 3.29 Ncm), and G3 (26.14 ± 2.12 Ncm). CONCLUSION: The association of blasting and bonding on abutment surface can be used to prevent screw loosening in Morse taper implants.

Comparative analysis of imaging techniques for diagnostic accuracy of peri-implant bone defects: a meta-analysis.

OBJECTIVE: The aim of this study was to systematically review the literature regarding diagnostic accuracy of imaging techniques in detecting peri-implant bone defects. STUDY DESIGN: The search was performed in 8 electronic databases from April to May 2016 and updated in September 2016. Studies that assessed imaging techniques to detect peri-implant bone defects were analyzed. RESULTS: The search yielded 680 articles published from 1991 to 2016. Of these, 12 studies were considered eligible for this review. The selected studies evaluated the use of cone beam computed tomography (CBCT), intraoral radiography (IR), computed tomography, and panoramic radiography. The sensitivity for CBCT was 59%, whereas the specificity was 67%. For IR, the sensitivity was 60%, and the specificity was 59%. Area under the curve values in receiver operating characteristic (ROC) analysis were 69% for CBCT and 63% for IR. For CBCT, the highest value for positive predictive value was 0.94, negative predictive value was 0.98, positive likelihood ratio was 21.3, and negative likelihood ratio was 1.28. For IR, the highest positive predictive value was 1.0, negative predictive value 1.0, positive likelihood ratio 50.0, and negative likelihood ratio 0.70. The highest diagnostic odds ratio was 80 for CBCT and 4.45 for IR. No conclusion could be drawn for additional techniques. CONCLUSIONS: Both CBCT and IR showed a clinically acceptable performance for assessing peri-implant bone defects.

Accuracy of linear measurements around dental implants by means of cone beam computed tomography with different exposure parameters.

OBJECTIVES: The aim of this study was to determine the accuracy of linear measurements around dental implants when using CBCT unit devices presenting different exposure parameters. METHODS: Dental implants (n = 18) were installed in the maxilla of human dry skulls, and images were obtained using two CBCT devices: G1-Care Stream 9300 (70 kVp, 6.3 mA, voxel size 0.18 mm, field of view 8 × 8 cm; Carestream Health, Rochester, NY) and G2-R100 Veraview® (75 kVp, 7.0 mA, voxel size 0.125 mm, field of view 8 × 8 cm; J Morita, Irvine, CA). Measurements of bone thickness were performed at three points located (A) in the most apical portion of the implant, (B) 5 mm above the apical point and (C) in the implant platform. Afterwards, values were compared with real measurements obtained by an optical microscopy [control group (CG)]. Data were statistically analyzed with the significance level of p ≤ 0.05. RESULTS: There was no statistical difference for the mean values of bone thickness on Point A (CG: 4.85 ± 2.25 mm, G1: 4.19 ± 1.68 mm, G2: 4.15 ± 1.75 mm), Point B (CG: 1.50 ± 0.84 mm, G1: 1.61 ± 1.27 mm; G2: 1.68 ± 0.82 mm) and Point C (CG: 1.78 ± 1.33 mm, G1: 1.80 ± 1.09 mm; G2: 1.64 ± 1.11 mm). G1 and G2 differed in bone thickness by approximately 0.76 mm for Point A, 0.36 mm for Point B and 0.08 mm for Point C. A lower intraclass variability was identified for CG (Point A = 0.20 ± 0.25; Point B = 0.15 ± 0.20; Point C = 0.06 ± 0.05 mm) in comparison with G1 (Point A = 0.56 ± 0.52; Point B = 0.48 ± 0.50; Point C = 0.47 ± 0.56 mm) and G2 (Point A = 0.57 ± 0.51; Point B = 0.46 ± 0.46; Point C = 0.36 ± 0.31 mm). CONCLUSIONS: CBCT devices showed acceptable accuracy for linear measurements around dental implants, despite the exposure parameters used.

Bone defect rehabilitation using lyophilized bone preshaped on a stereolithographic model.

Bone grafting provides ideal conditions to the patient's rehabilitation with dental implants. In addition, prototyped tridimensional models allow the surgical procedure to be simulated and enable important anatomic structures to be visualized. To present a bone defect rehabilitated with xenogenic bone preshaped on a stereolithographic model and the follow-up after 7 years of treatment. The present case report describes a bone defect rehabilitated with a lyophilized bone block preshaped on a stereolithographic model. The patient, a 56-year-old woman, was referred to the dental office presenting a bone defect in the anterior maxilla. Bone regeneration intervention was performed with xenogenic grafting and barrier membrane. The follow-up of the postoperative period and after 7 years is presented. After 7 years, the tomographic exam showed the maintenance of bone at the grafted site, representing the long-term success of the treatment.

Clinical and Histomorphometric Evaluation of Fresh Frozen Bone Allograft in Sinus Lift Surgery.

PURPOSE: The aim of this prospective clinical study was to evaluate the clinical and histomorphometric data of newly formed bone tissue from fresh frozen human allograft in sinus lift surgery. PATIENTS AND METHODS: Thirty-three sinus lift procedures were performed in 20 patients, divided into two groups. The control group (n = 8) received autogenous bone from the mandibular ramus, and the experimental group (n = 12) received fresh frozen bone (FFB) allograft in chips. After 6 months, 52 implants were placed and 50 biopsies were collected for histomorphometric analysis. Cone beam computed tomography scans were performed at preoperative, immediate postoperative, and delayed postoperative time intervals to assess the degree of graft volume loss. RESULTS: There was no statistically significant difference between groups as regards degree of graft volume loss (p = .983), total bone area (p = .191), remaining particles (p = .348), and proportion of active osteoblasts (p = .867). There was a statistically significant difference in the vitality rate between the groups (p = .043). In both groups, all implants were clinically osseointegrated after 4 months. CONCLUSION: FFB allograft was shown to be a feasible substitute for autogenous bone graft in sinus lift surgery.

Accuracy of a self-perforating impression tray for dental implants.

STATEMENT OF PROBLEM: Difficulties are involved in impression making with conventional open impression trays. PURPOSE: The purpose of this study was to evaluate the accuracy of transferring implant impressions with a self-perforating impression tray. MATERIAL AND METHODS: A reference model of a mandible was fabricated, and 4 implants were placed in the regions of the first premolars and lateral incisors (implants 1, 2, 3, 4). Ten impressions of the reference model with polyvinyl siloxane were made for each group; control (conventional open impression tray) and test (self-perforating impression tray; Miratray Implant). A metal bar was screw-retained on implant 1, and the gaps generated at the vestibular face of implants 3 and 4 were measured by optical microcopy. The 2-way ANOVA and least square difference post hoc test were used (α=.05). RESULTS: Higher mean (±SD) values were obtained for the test group than for the control group for both implants: implant 3: 150 ±84 µm for the test group, 73 ±63 µm for the control group (P=.019); implant 4: 129 ±65 µm for the test group, 62 ±61 µm for the control group (P=.04). CONCLUSION: The self-perforating impression tray provided less accuracy than the conventional open tray.

Assessment of the stress transmitted to dental implants connected to screw-retained bars using different casting techniques.

Passive fit of the prosthetic superstructure is important to avoid complications; however, evaluation of passive fit is not possible using conventional procedures. Thus, the aim of this study was to check and locate mechanical stress in bar restorations fabricated using two casting techniques. Fifteen patients received four implants in the interforaminal region of the mandible, and a bar was fabricated using either the cast-on abutment or lost-wax casting technique. The fit accuracy was checked according to the Sheffield's test criteria. Measurements were recorded on the master model with a gap-free, passive fit using foil strain gauges both before and after tightening the prosthetic screws. Data acquisition and processing was analyzed with computer software and submitted to statistical analysis (ANOVA). The greatest axial distortion was at position 42 with the cast-on abutment technique, with a mean distortion of 450 µm/m. The lowest axial distortion occurred at position 44 with the lost-wax casting technique, with a mean distortion of 100 µm/m. The minimal differences between the means of axial distortion do not indicate any significant differences between the techniques (P = 0.2076). Analysis of the sensor axial distortion in relation to the implant position produced a significant difference (P < 0.0001). Significantly higher measurements were recorded in the axial distortion analysis of the distal sensors of implants at the 34 and 44 regions than on the mesial positions at the 32 and 42 regions (P = 0.0481). The measuring technique recorded axial distortion in the implant-supported superstructures. Distortions were present at both casting techniques, with no significant difference between the sides.

Recent advances of ultrasound imaging in dentistry--a review of the literature.

Ultrasonography as an imaging modality in dentistry has been extensively explored in recent years due to several advantages that diagnostic ultrasound provides. It is a non-invasive, inexpensive, painless method and unlike X-ray, it does not cause harmful ionizing radiation. Ultrasound has a promising future as a diagnostic imaging tool in all specialties in dentistry, for both hard and soft tissue detection. The aim of this review is to provide the scientific community and clinicians with an overview of the most recent advances of ultrasound imaging in dentistry. The use of ultrasound is described and discussed in the fields of dental scanning, caries detection, dental fractures, soft tissue and periapical lesions, maxillofacial fractures, periodontal bony defects, gingival and muscle thickness, temporomandibular disorders, and implant dentistry.

Decontamination of dental implant surfaces by means of photodynamic therapy.

Several implant surface debridement methods have been reported for the treatment of peri-implantitis, however, some of them can damage the implant surface or promote bacterial resistance. Photodynamic therapy (PDT) is a new treatment option for peri-implantitis. The aim of this in vitro study was to analyze implant surface decontamination by means of PDT. Sixty implants were equally distributed (n = 10) into four groups and two subgroups. In group G1 there was no decontamination, while in G2 decontamination was performed with chlorhexidine. G3 (PDT - laser + dye) and G4 (laser, without dye) were divided into two subgroups each; with PDT performed for 3 min in G3a and G4a, and for 5 min in G3b and G4b. After 5 min in contact with methylene blue dye (G3), the implants were irradiated (G3 and G4) with a low-level laser (GaAlAs, 660 nm, 30 mW) for 3 or 5 min (7.2 and 12 J). After the dilutions, culture media were kept in an anaerobic atmosphere for 1 week, and then colony forming units were counted. There was a significant difference (p < 0.001) between G1 and the other groups, and between G4 in comparison with G2 and G3. Better decontamination was obtained in G2 and G3, with no statistically significant difference between them. The results of this study suggest that photodynamic therapy can be considered an efficient method for reducing bacteria on implant surfaces, whereas laser irradiation without dye was less efficient than PDT.

Moldagem em implantodontia / Impression in implantodontics

Neste artigo é realizada uma revisão da literatura sobre moldagem em Implantodontia. São descritos os diferentes tipos de materiais de moldagem utilizados e principais propriedades, tipos de moldeiras, diferentes técnicas de moldagem e métodos e dos modelos obtidos. Suas composições, propriedades, vantagens e desvantagens são apresentadas e comparadas, além de como as técnicas e materiais podem influenciar as decisões clínicas

Estabelecimento de um protocolo de higienização para prevenção de mucosites e peri-implantites / Establishment of a supportive hygiene protocol to prevent mucosal and peri-implant lesions

Com os avanços tecnológicos e o aperfeiçoamento das técnicas cirúrgicas, a reabilitação oral através da prótese implantossuportada está se tornando o tratamento de eleição para um grande número de casos. Porém, o aumento da incidência de mucosite e peri-implantite pode comprometer a longevidade deste tipo de reabilitação oral. Infelizmente, a preocupação com a higienização dos implantes não tem acompanhado toda a evolução que está ocorrendo nesta área do conhecimento. Se quisermos a manutenção do processo de osseointegração em longo prazo, é fundamental o estabelecimento imediato de um protocolo de higienização eficiente e atraumático de acordo com as diferentes soluções protéticas possíveis

Due to the technological advances and improvements on surgical techniques, the implant-supported oral rehabilitation has become the first treatment choice in many cases. However, the increased incidence of mucositis and peri-implantitis could compromise its long-term function. Unfortunately, the level of awareness on implant supportive therapy has not reached the same level. If one wants to preserve the osseointegration process in a long-term basis, the main point is the establishment of an efficient and atraumatic implant prophylaxis protocol in accordance with different rehabilitation modalities

Immediate implant placement and restoration in the esthetic zone: a prospective study with 18 months of follow-up.

PURPOSE: This clinical study aimed to assess the dimensional stability of peri-implant soft tissues around immediately placed and restored implants in the maxillary esthetic zone. MATERIALS AND METHODS: Twelve systemically healthy patients presenting with a hopeless maxillary central incisor were selected. Provisional restorations were delivered immediately after tooth extraction and implant placement. Periimplant soft tissue dimensions were measured either by direct clinical examination or evaluation of study casts. Measurements were performed before extraction; immediately after implant and restoration placement; and 6 weeks, 3 months, 6 months, 12 months, and 18 months postoperatively. The distances assessed were: tip of the mesial papilla to the mesioincisal edge of the adjacent central incisor, tip of the distal papilla to the mesioincisal edge of the adjacent lateral incisor, and the length of the clinical crown of the definitive restoration. RESULTS: All patients completed the study, and no implants failed within the 18-month follow-up period (100% survival rate). No statistical differences were observed in the distances between the incisal edge of the adjacent teeth and the mesial and distal papilla tips (P = .303 and .099, respectively) at any follow-up appointment. Likewise, there were no alterations in the definitive clinical crown dimensions during the follow-up period (P = .406). CONCLUSION: The findings of this 18-month prospective study indicate that, within the selection criteria and technique presented in this study, immediate implants with immediate restorations can be a predictable option for the replacement of teeth in the esthetic zone, providing stability to the peri-implant soft tissue.

Outcomes of fixed prostheses supported by immediately loaded endosseous implants.

PURPOSE: The aim of this article was to evaluate the survival and success of Straumann implants after immediate loading. A new method for fabricating effective definitive prostheses to immediately load implants in edentulous patients was presented. MATERIALS AND METHODS: Nine patients received 4 implants each, and resin-metal prostheses were installed less than 48 hours after implant placement. Mobility was evaluated immediately after the surgical procedures and 3 months subsequently using the Periotest. Clinical evaluation of soft peri-implant tissues was conducted monthly after the sutures were removed, and radiographs were obtained 6, 12, and 24 months after the surgery. RESULTS: The Periotest revealed statistical values that were stable, with no mobility. No signs of inflammation and/or bleeding were observed. The radiographs did not reveal any continuous areas of radiolucency beyond the first thread of the 36 implants after 24 months. None of them failed, and the success rate was 100%. DISCUSSION: It is possible to submit implants to immediate load without jeopardizing osseointegration if parameters are met, such as suitable bone quality and quantity, lack of unfavorable systemic and psychologic factors, lack of parafunctional habits, strict maintenance of prosthetic requirements, minimization of micromotion, and use of an appropriate surgical protocol. CONCLUSION: Under immediate load, osseointegration of implants is possible, and the method presented for the fabrication of resin-metal prostheses has been reliable and predictable.

Conduta de planejamento em setores estéticos associados à carga imediata - Descrição de caso clínico / Planning procedures for esthethic areas in association with immediate load - A clinical case report

A Implantodontia alterou o planejamento da reabilitação de elementos dentais perdidos com uma previsibilidade muito grande. Quando esse tema é associado a estética, o assunto torna-se extremamente complexo, uma vez que os fatores envolvidos para obtenção de resultados previsíveis são inúmeros4. Nos setores anteriores, mesmo quando a reabilitação com implantes parece favorável, sob o ponto de vista estético, o minucioso planejamento do caso clínico é fundamental para a obtenção de resultados ideais. Apresentamos um caso clínico onde utilizamos uma técnica de planejamento para diagnosticar e solucionar problemas estéticos, associando, além dos conceitos tradicionais, a carga imediata para otimizar os resultados