Stress distribution on different bar materials in implant-retained palatal obturator.

Implant-retained custom-milled framework enhances the stability of palatal obturator prostheses. Therefore, to evaluate the mechanical response of implant-retained obturator prostheses with bar-clip attachment and milled bars, in three different materials under two load incidences were simulated. A maxilla model which Type IIb maxillary defect received five external hexagon implants (4.1 x 10 mm). An implant-supported palatal obturator prosthesis was simulated in three different materials: polyetheretherketone (PEEK), titanium (Ti:90%, Al:6%, V:4%) and Co-Cr (Co:60.6%, Cr:31.5%, Mo:6%) alloys. The model was imported into the analysis software and divided into a mesh composed of nodes and tetrahedral elements. Each material was assumed isotropic, elastic and homogeneous and all contacts were considered ideal. The bone was fixed and the load was applied in two different regions for each material: at the palatal face (cingulum area) of the central incisors (100 N magnitude at 45°); and at the occlusal surface of the first left molar (150 N magnitude normal to the surface). The microstrain and von-Mises stress were selected as criteria for analysis. The posterior load showed a higher strain concentration in the posterior peri-implant tissue, near the load application side for cortical and cancellous bone, regardless the simulated material. The anterior load showed a lower strain concentration with reduced magnitude and more implants involving in the load dissipation. The stress peak was calculated during posterior loading, which 77.7 MPa in the prosthetic screws and 2,686 µÎµ microstrain in the cortical bone. For bone tissue and bar, the material stiffness was inversely proportional to the calculated microstrain and stress. However, for the prosthetic screws and implants the PEEK showed higher stress concentration than the other materials. PEEK showed a promising behavior for the bone tissue and for the integrity of the bar and bar-clip attachments. However, the stress concentration in the prosthetic screws may represent an increase in failure risk. The use of Co-Cr alloy can reduce the stress in the prosthetic screw; however, it increases the bone strain; while the Titanium showed an intermediate behavior.

Remodelling of sinus bone grafts according to the distance from the native bone: A histomorphometric analysis.

OBJECTIVES: To evaluate graft remodelling according to the distance from the native bone in maxillary sinuses grafted with anorganic bovine bone (ABB). MATERIAL AND METHODS: Bilateral sinus grafting was performed in twenty patients with residual bone height <5 mm before implant placement. After 8 months, biopsy samples were harvested, and histomorphometric analysis was performed to examine bone formation according to the distance (in mm) from the native bone (sinus floor). In the grafted area, the percentages of new bone (NB), residual graft material (rABB), and soft tissue (ST) were evaluated. RESULTS: A total of 103 biopsy samples were evaluated, and the percentages of NB, rABB, and ST were 31.62 ± 9.85%, 18.94 ± 7.88%, and 49.41 ± 9.52%, respectively, in the 1st mm; 27.15 ± 9.83%, 23.33 ± 9.45%, and 49.53 ± 11.73%, respectively, in the 2nd mm; 23.61 ± 13.02%, 21.35 ± 11.08%, and 55.03 ± 16.14%, respectively, in the 3rd mm; and 21.67 ± 12.29%, 19.67 ± 10.28%, and 58.66 ± 12.46%, respectively, in the 4th mm. The 1st millimetre of the grafted area (closer to the native bone) presented a larger amount of NB than the other portions of the grafted areas and a smaller amount of rABB than the 2nd mm of the grafted area (p < .05). The amount of ST was larger in the 3rd and 4th mm of the grafted area than in the first 2 millimetres (p < .05). CONCLUSION: The distance from the native bone influences bone formation following maxillary sinus augmentation.

Influence of residual bone height and sinus width on the outcome of maxillary sinus bone augmentation using anorganic bovine bone.

OBJECTIVE: To evaluate the influence of the posterior residual bone height and sinus width on the outcome of maxillary sinus bone augmentation using anorganic bovine bone. MATERIAL AND METHODS: Bilateral sinus bone augmentation was performed using anorganic bovine bone in 20 patients with residual bone height <2 mm in at least one site on each side. Trephine samples were removed at the implant insertion site 8 months after the grafting procedure, and histological and histomorphometric analyses were performed to examine the relative amount (%) of new bone, anorganic bovine bone, and soft tissue in the grafted area. Based on cone beam computed tomography evaluation, the sites of implant insertion were classified according to sinus width into narrow, average, and wide, and according to residual bone height into ≤2 and >2 mm. RESULTS: A total of 146 implants were installed and 103 biopsies were evaluated. New bone formation in sites classified as narrow (69 sites), average (19 sites), and wide (15 sites) was 28.5% ± 9.24, 28.9% ± 8.61, and 30.3% ± 7.80, respectively. The mean posterior maxillary residual bone height was 4.0 ± 2.43 mm, and 26 and 77 sites were classified as ≤2 and >2 mm, respectively. New bone formation was 26.2% ± 9.10 and 29.8% ± 8.67 for residual bone height ≤2 and >2 mm, respectively. The differences were non-significant. CONCLUSIONS: Within the limitations of the present study, posterior residual bone height and sinus width were not factors with influence on new bone formation in sinuses grafted exclusively with anorganic bovine bone after 8 months of healing.

Improving gingival smile by means of guided bone regeneration principles.

OBJECTIVE: This study evaluated the effectiveness of guided bone regeneration (GBR) carried out with xenogenic bone substitute (Bio-OssTM) and collagen resorbable membrane (Bio-GideTM) to improve gingival smile (GS) in patients with excessive vertical maxillary growth (EVMG). METHODS: Twelve healthy women aged between 20 and 49 years old (mean age of 26 years), with 5 mm or more of gingival exposure during fully posed smile (FPS) due to EVMG, were included. Baseline digital photographs were taken with standardized head position at rest and FPS. In eight out of 12 cases, crown lengthening procedure was indicated and the initial incision was made 2 to 4 mm from the gingival margin. In four cases, with no indication for crown lengthening procedure, a sulcular incision was performed. GBR was performed in all cases, using micro screws and/or titanium mesh associated with Bio-OssTM and Bio-GideTM. After 10 days, sutures were removed. Recall appointments were scheduled at 1, 6, and 12 months when standardized photographs were again taken. ImageToolTM software was used to measure the gingival exposure (GE) during FPS from the standardized close-up smile photographs at baseline and 12 months. RESULTS: GE mean at baseline was 275.44 mm2. After 12 months, patients who undergone exclusively GBR procedure, presented GE reduction of 40.7%, ∆ = 112.01 mm2 (statistically significant, p = 0.12), and patients who had crown lengthening associated with the graft had a reduction of 60%, ∆ = 167.01 mm2. CONCLUSION: Our results using GBR to improve GS in cases of EVMG showed an exceptionally high patient acceptance and satisfaction. One-year follow-up confirmed stable results.

Improving gingival smile by means of guided bone regeneration principles

ABSTRACT Objective: This study evaluated the effectiveness of guided bone regeneration (GBR) carried out with xenogenic bone substitute (Bio-OssTM) and collagen resorbable membrane (Bio-GideTM) to improve gingival smile (GS) in patients with excessive vertical maxillary growth (EVMG). Methods: Twelve healthy women aged between 20 and 49 years old (mean age of 26 years), with 5 mm or more of gingival exposure during fully posed smile (FPS) due to EVMG, were included. Baseline digital photographs were taken with standardized head position at rest and FPS. In eight out of 12 cases, crown lengthening procedure was indicated and the initial incision was made 2 to 4 mm from the gingival margin. In four cases, with no indication for crown lengthening procedure, a sulcular incision was performed. GBR was performed in all cases, using micro screws and/or titanium mesh associated with Bio-OssTM and Bio-GideTM. After 10 days, sutures were removed. Recall appointments were scheduled at 1, 6, and 12 months when standardized photographs were again taken. ImageToolTM software was used to measure the gingival exposure (GE) during FPS from the standardized close-up smile photographs at baseline and 12 months. Results: GE mean at baseline was 275.44 mm2. After 12 months, patients who undergone exclusively GBR procedure, presented GE reduction of 40.7%, ∆ = 112.01 mm2 (statistically significant, p = 0.12), and patients who had crown lengthening associated with the graft had a reduction of 60%, ∆ = 167.01 mm2. Conclusion: Our results using GBR to improve GS in cases of EVMG showed an exceptionally high patient acceptance and satisfaction. One-year follow-up confirmed stable results.

RESUMO Objetivo: o presente estudo avaliou a eficácia da regeneração óssea guiada (ROG) usando enxerto ósseo xenógeno (Bio-Oss(r)) e membrana de colágeno reabsorvível (Bio-Gide(r)) para melhorar a estética do "sorriso gengival" (SG) em pacientes com crescimento maxilar vertical excessivo (CMVE). Métodos: foram incluídas 12 mulheres saudáveis com idades entre 20 e 49 anos (média = 26 anos) com 5mm ou mais de exposição gengival durante o sorriso amplo posado (SAP), em função de CMVE. Foram realizadas fotografias digitais padronizadas (FDP) em repouso e em SAP. Em 8 dos 12 casos, foi indicado o procedimento de aumento da coroa clínica, e a incisão inicial foi realizada de 2 a 4mm da margem gengival. Em 4 casos, para os quais não houve indicação de aumento da coroa clínica, foi realizada uma incisão intrassulcular. A ROG foi realizada, em todos os casos, utilizando-se mini-implantes e/ou malha de titânio, associados a Bio-Oss(r) e Bio-Gide(r). Após 10 dias, as suturas foram removidas. O programa ImageTool(r) foi utilizado para medir a "área gengival exposta" (AGE) durante o SAP, nas imagens padronizadas do sorriso, em close-up, ao início do estudo e após 12 meses. Resultados: a média da AGE no início do estudo foi de 275,44mm2. Após 12 meses, os pacientes submetidos exclusivamente ao procedimento de ROG apresentaram redução na AGE de 40,7%, Δ = 112,01mm2 (estatisticamente significativo, p = 0,12); já nos pacientes em que o aumento de coroa clínica foi associado ao enxerto, a redução foi de 60%, Δ = 167,01mm2. Conclusão: os resultados do uso da ROG para melhorar o SG em casos de CMVE demonstraram aceitação e satisfação extremamente elevadas por parte dos pacientes. O acompanhamento de 1 ano pós-tratamento confirmou a estabilidade dos resultados.

Orthodontic approach to treat complex hypodontia using miniscrews in a growing patient.

This article reports orthodontic treatment of a case of hypodontia of five premolars in an 11-year-old female patient with a positive tooth size-arch length discrepancy in both dental arches. The patient had a straight profile with balanced facial growth. Setup manufacture revealed the possibility of achieving ideal occlusion by mesializing permanent molars up to 15 mm, in addition to keeping a primary molar in the dental arch. With the aid of absolute anchorage, the proposed mechanics was performed and the occlusion predicted in the setup was achieved, while profile and facial growth pattern were maintained. The use of miniscrews for extensive orthodontic movements was successful. Furthermore, one primary molar was extensively mesialized. The indication of gingivoplasty to correct gingival smile proved effective. This is considered a useful technique for orthodontists.

Orthodontic approach to treat complex hypodontia using miniscrews in a growing patient

This article reports orthodontic treatment of a case of hypodontia of five premolars in an 11-year-old female patient with a positive tooth size-arch length discrepancy in both dental arches. The patient had a straight profile with balanced facial growth. Setup manufacture revealed the possibility of achieving ideal occlusion by mesializing permanent molars up to 15 mm, in addition to keeping a primary molar in the dental arch. With the aid of absolute anchorage, the proposed mechanics was performed and the occlusion predicted in the setup was achieved, while profile and facial growth pattern were maintained. The use of miniscrews for extensive orthodontic movements was successful. Furthermore, one primary molar was extensively mesialized. The indication of gingivoplasty to correct gingival smile proved effective. This is considered a useful technique for orthodontists.

Este artigo apresenta o tratamento ortodôntico de um caso com hipodontia de cinco pré-molares, em uma paciente, de 11 anos de idade, com discrepância positiva de modelo em ambas as arcadas. A paciente apresentava perfil reto, com crescimento facial equilibrado. Por meio da confecção de set-up, verificou-se a possibilidade de se estabelecer uma oclusão ideal por meio da mesialização, de até 15mm, dos molares permanentes e manutenção de um molar decíduo no arco. Com o auxílio de ancoragem absoluta, foi realizada a mecânica proposta, alcançando-se a oclusão prevista em set-up, além da manutenção do perfil e do padrão de crescimento facial. A utilização de mini-implantes para grandes movimentos ortodônticos foi favorável, incluindo a extensa mesialização de um molar decíduo. A indicação da gengivoplastia para correção do sorriso gengival se mostrou acertada, sendo essa uma técnica de grande auxílio à Ortodontia.

Grafting the nasal cavity with 100% anorganic bovine bone: a clinical and histomorphometric pilot report.

PURPOSE: The aim of the present study was to evaluate bone formation and survival rates for implants after nasal cavity grafting using exclusively anorganic bovine bone (ABB) by means of clinical, radiographic, and histologic/histomorphometric examinations. MATERIALS AND METHODS: Twelve subjects with edentulous atrophic maxillae were screened for the study; four required bilateral and eight required unilateral nasal cavity grafting. A full-thickness flap was raised to determine the position for the nasal window between the anterior wall of the sinus and the lateral wall of the piriform aperture. A window, 5 to 6 mm wide and 10 to 13 mm high, was created. The window was infractured into the nasal cavity to allow the ABB to be pushed inside and was then covered with a collagen membrane. Cone beam computed tomography (CBCT) was performed before grafting (during screening), after grafting, and 6 months later. Eight months after grafting, from the 16 sites grafted, biopsy cores were taken from three patients using a 2.5-mm trephine and processed to evaluate the percentages of new bone, marrow space, and residual ABB. One screw-form implant was placed in each grafted site and loaded after 3 months. After at least 6 months of loading, the fixed prostheses were removed and all implants placed in grafted areas were tested for mobility. RESULTS: The 6-month CBCTs clearly showed the radiopaque material inside the nasal cavity. The histomorphometric measurements showed 33.34% new bone, 30.30% marrow space, and 36.52% remaining ABB. All implants were osseointegrated and free of pain, infection, and mobility. All implants remained stable at a mean of 13 months after loading (range, 6 to 24 months). CONCLUSIONS: The clinical, radiographic, and histomorphometric results showed that nasal cavity grafting with ABB can be an excellent alternative in patients with extensively atrophic maxillae.