6 research outputs found
The occlusal precision of milled versus printed provisional crowns
No full textObjectives: The aim of this study was to compare the occlusal precision of computer-aided-design/ computerassisted-manufacturing (CAD/CAM) milled versus 3D printed polymethylmethacrylate (PMMA) temporary prosthetic crowns , starting from the same digital CAD design. Materials and methods: The study sample included 34 patients presenting 34 premolars in need of prosthetic rehabilitation: a total of 68 temporary crowns were manufactured, 34 of which milled and 34 printed. Immediately after manufacturing, the milled and printed provisionals were scanned with a desktop scanner (E1, 3Shape) to obtain STL files, that were superimposed to the original CAD design in order to identify the occlusal trueness (Analysis A). A second occlusal comparison was performed by scanning both kind of provisional after being placed intraorally with Trios scanner (3 Shape); intraoral scans were obtained in order to compare STL files of provisionals before and after occlusal adjustments (Analysis B). The occlusal trueness was identified at three reference points, P1 (vestibular cusp), P2 (palatal / lingual cusp), P3 (central fossa). The statistical analysis was performed using the R 3.4.3 statistical software (The R Foundation for Statistical Computing), with a significance level of p <0.05. Results: Overall, the printed crowns showed lower occlusal differences than the milled crowns, when compared to the CAD design file, with a statistically significant difference in P1 (difference of 0.025 +/- 0.046 mm), P2 (difference of 0.027 +/- 0 0.044 mm) and P3 ( difference of 0.018 +/- 0.050) for Analysis A (p <0.05). In the Analysis B the direct comparison between the degree of average difference between the pre-adjustment and the post-occlusal adjustment of the milled and printed crowns shows that the printed crowns have lower occlusal mean difference values in all three points compared to the milled ones (difference of 0.146 +/- 0.273 mm in P1, 0.285 +/- 0.360 mm in P2 and 0.257 +/- 0.277 mm in P3). Conclusions: Within the limitation of this study, the data obtained showed a better occlusal surface dimensional accuracy of the 3D printed provisional crowns, when compared to the milled ones. Comparing the results obtained, it is possible to assume that the intraoral scans also had a contribution to occlusion, beside the manufacturing method. 3D printing can be successfully applied for manufacturing temporary PMMA crowns
Autotransplantation of retained canines unable to undergo orthodontic traction. A clinical report
No full textAim: The canine is the tooth that, together with the third molar, presents the highest risk of inclusion: 85% of these teeth are located in the palate and 15% in the buccal area. In most treatment plans, retained canines are driven to extrusion through orthodontic treatment. However, in some cases, for technical reasons or patient choice, it is not possible to perform this consolidated approach. The present clinical report evaluates 10 ectopic canines transplanted in both adults and younger patients with up to 60 months of follow-up. Case description: Two clinical cases are described in detail with accompanying photographs and radiographs. In both of these cases, the retained canine was extracted, the receiving site prepared, a proper socket adapted through the use of implant osteotomy burs, and the canine transplanted into its ideal position. The tooth was fixed to the adjacent teeth for a variable period and healing was uneventful. After 60 months (Case 1) and 24 months (Case 2) of follow-up, the teeth did not show any color variation, the vitality tests were positive, and no signs of periapical reactions were detected. Practical implications: The transplantation of included canines, even with a formed apex, seems to be a successful procedure, although it should be reserved for those cases where an orthodontic approach is not viable. This procedure is able to provide a natural tooth with proprioceptive function, capable of accompanying the natural growth of the patient's jaws, with consequent eruption together with the adjacent teeth
Increasing the Vertical Dimension of Occlusion: A Multicenter Retrospective Clinical Comparative Study on 100 Patients with Fixed Tooth-Supported, Mixed, and Implant-Supported Full-Arch Rehabilitations
No full textThis multicenter retrospective clinical study was aimed at comparing the effects of an increase in vertical dimension of occlusion (VDO) in patients with fixed rehabilitations. Expert clinicians retrospectively evaluated 100 patients treated with an increase of the VDO and fixed dental prostheses (FDPs) supported by teeth, implants, or both. The patients were divided into three study groups according to the type of support of restorations in posterior areas, as follows: partially edentulous patients with posterior teeth-supported rehabilitations and no implants in posterior segments (group A), partially edentulous patients with posterior mixed rehabilitations and at least one osseointegrated implant in posterior segments (group B), and completely edentulous patients with posterior implant-supported rehabilitations (group C). The new VDO was tested with mock-ups, temporary restorations, or removable appliances. The patients were followed up for at least 1 year after the delivery of final restorations. Clinical variables were collected retrospectively, such as presence of referred self-reported bruxism and temporomandibular joint or muscle symptoms before treatment, extension of the dental arches, increase in VDO, restorative materials, and functional complications. Descriptive statistics were analyzed; the three experimental groups were compared with one-way analysis of variance (ANOVA) followed by Tukey post hoc test for the quantitative variables and with logistic regression using the likelihood ratio test for the qualitative variables. Statistically significant differences were reported among the experimental groups for functional complications. Functional and prosthetic complications after the VDO increase were not frequent. Functional complications were mainly noticed in group C but usually were no longer evident after 2 weeks. No significant differences were found between groups in terms of prosthetic complications and self-reported bruxism
Rehabilitation of a patient with mini‐implants after avulsion of the upper incisors: A 13‐year follow up
No full textHealing of implants installed in over- or under-prepared sites: an experimental study in dogs
No full textObjectiveTo study bone healing at implants installed with different insertion torques.Material and methodsIn six Labrador dogs, all mandibular premolars and first molars were extracted. After 4months of healing, flaps were elevated, and two implant sites were prepared at each side of the mandible. In the right side of the mandible, the distal sites were prepared conventionally, while the mesial sites were over-prepared by 0.2mm. As a consequence, a final insertion torque of similar to 30Ncm at the distal and a minimal insertion torque close to 0Ncm at the mesial sites were obtained. In the left sides of the mandible, however, the recipient sites were underprepared by 0.3mm resulting in an insertion torque of 70Ncm at both implants. Cover screws were applied, and flaps sutured to fully submerge the experimental sites. After 4months, the animals were sacrificed and ground sections obtained for histological evaluation.ResultsThe mineralized bone-to-implant contact was in the range of 55.2-62.1%, displaying the highest value at implants with similar to 30Ncm insertion torque and the lowest value at the implant sites with close to 0Ncm insertion torque. No statistically significant differences were revealed. Bone density was in the range of 43.4-54.9%, yielding the highest value at implants with 70Ncm insertion torque and the lowest at the implant sites with close to 0Ncm insertion torque. The difference between the sites of similar to 30Ncm and the corresponding 70Ncm insertion torque reached statistical significance.ConclusionsSimilar amounts of osseointegration were obtained irrespective of the insertion torque applied. Moreover, implants installed in sites with close to 0Ncm insertion torque may properly osseointegrate as well.OSSTEM Seoul, South KoreaARDEC, Ariminum Odontologica SRL, Rimini, ItaliaClinical Research Foundation (CRF) for the Promotion of Oral Health, Brienz, SwitzerlandUniv Med Sci, Fac Dent, Havana, CubaUniv Hong Kong, Prince Philip Dent Hosp, Hong Kong, Hong Kong, Peoples R ChinaUniv Zurich, Zurich, SwitzerlandUniv Padoa, Padua, ItalyUniv Estadual Paulista, UNESP, Fac Odontol Aracatuba, Sao Paulo, BrazilAriminum Odontol, ARDEC, Rimini, ItalyUNESP Universidade Estadual Paulista, Faculdade de Odontologia Araçatuba, Sao Paulo, Brazi
Healing of implants installed in over- or under-prepared sites--an experimental study in dogs
No full textOBJECTIVE To study bone healing at implants installed with different insertion torques. MATERIAL AND METHODS In six Labrador dogs, all mandibular premolars and first molars were extracted. After 4 months of healing, flaps were elevated, and two implant sites were prepared at each side of the mandible. In the right side of the mandible, the distal sites were prepared conventionally, while the mesial sites were over-prepared by 0.2 mm. As a consequence, a final insertion torque of ~30 Ncm at the distal and a minimal insertion torque close to 0 Ncm at the mesial sites were obtained. In the left sides of the mandible, however, the recipient sites were underprepared by 0.3 mm resulting in an insertion torque of ≥ 70 Ncm at both implants. Cover screws were applied, and flaps sutured to fully submerge the experimental sites. After 4 months, the animals were sacrificed and ground sections obtained for histological evaluation. RESULTS The mineralized bone-to-implant contact was in the range of 55.2-62.1%, displaying the highest value at implants with ~30 Ncm insertion torque and the lowest value at the implant sites with close to 0 Ncm insertion torque. No statistically significant differences were revealed. Bone density was in the range of 43.4-54.9%, yielding the highest value at implants with ≥ 70 Ncm insertion torque and the lowest at the implant sites with close to 0 Ncm insertion torque. The difference between the sites of ~30 Ncm and the corresponding ≥ 70 Ncm insertion torque reached statistical significance. CONCLUSIONS Similar amounts of osseointegration were obtained irrespective of the insertion torque applied. Moreover, implants installed in sites with close to 0 Ncm insertion torque may properly osseointegrate as well
