Effectiveness of Hyaluronic Acid Injection for Interdental Papillae Recovery in Esthetic Areas: A Randomized Clinical Trial.

The aim of this study was to evaluate the effectiveness of hyaluronic acid (HA) injections used to reduce defects in the gingival papillae in esthetic areas. This randomized study included six patients requiring black triangle treatment in 19 defective papillae. After local anesthesia, less than 0.2 mL of HA was injected 2 to 3 mm into the tip of the deficient papilla in the apical direction. Analysis of the target regions with standardized photographs and 3D intraoral scanning (CEREC 4.5 software with RST files, Dentsply Sirona) was performed at baseline (T0) and at 1 month (T1), 2 months (T2), 3 months (T3), and 4 months (T4) after the initial application of HA. At each time period, the photographic analysis showed no statistically significant differences in linear tissue gain after HA gel application. The 3D analysis showed improvements in the vertical papillae tissue recovery at T3 (0.41 ± 0.21 mm) and T4 (0.38 ± 0.21 mm) when compared to T1 (0.13 ± 0.08 mm; P < .0001). Regarding the reconstruction of the interdental papillae, the general dimensions of the tissue in the black triangle areas showed a significant increase in size percentage at T3 (58% ± 32.9%) compared to T1 (30.41% ± 23.4%; P = .0054). Thus, the application of injectable HA was effective for filling papillae in the esthetic area. Int J Periodontics Restorative Dent 2023;43:e73-e80. doi: 10.11607/prd.5814.

Assessment of Deviations of Implants Installed with Prototyped Surgical Guide and Conventional Guide: In Vitro Study.

OBJECTIVE: The study aimed to assess the angular and linear deviations of implants installed in mannequins aided by surgical guides produced with the techniques of dual tomography (DT), model-based tomography (MT), and nonprototyped guide. MATERIALS AND METHODS: Implants were installed in mannequins of a partially edentulous maxilla and divided into three groups: Group C (n = 20), implants installed using the conventional technique with flap opening and conventional guide; Group DT (n = 20), implants installed using guided surgery with the dual tomography technique; and Group MT (n = 20), implants installed using the model-based tomography technique. After implant installation, the mannequin was subjected to a computed tomography (CT) to measure the linear and angular deviations of implant positioning relative to the initial planning on both sides. RESULTS: There was a higher mean angular deviation in group C (4.61 ± 1.21, p ≤ 0.001) than in groups DT (2.13 ± 0.62) and MT (1.87 ± 0.94), which were statistically similar between each other. Similarly, the linear deviations showed group C with the greatest discrepancy in relation to the other groups in the crown (2.17 ± 0.82, p = 0.007), central (2.2 ± 0.77, p = 0.004), and apical (2.34 ± 0.8, p = 0.001) regions. CONCLUSION: The techniques of DT and MT presented smaller angular and linear deviations than the conventional technique with the nonprototyped guide. There was no difference between the two-guided surgery techniques.

Rehabilitation of a patient diagnosed with Ectodermal Dysplasia presenting hypodontia: a case report

Purpose: The study showed a patient with Ectodermal Dysplasia (ED) who was treated with implants and fixed dental prosthesis by a multidisciplinary team. Case Report: Acrylic resin dental prostheses were designed as long-term provisionals, which allowed modifications when required. After imaging and treatment planning, four implants were placed in the inter-foramenal area of the mandible and 2 years later the definitive prosthesis was fitted. In a second phase, the patient received a combination of autogenous and allogeneic bone grafts in the maxilla. The autogenous graft was removed from the retro-molar region in the mandible. He also received a fixed dental prosthesis supported by 4 implants on the position of the upper canines and second pre-molars. Conclusion: Patient reports successful outcomes and despite the long treatment, patient states is confident with his appearance and speaking improvement. Follow-up was done every six months, for 10 years, and showed encouraging post-treatment outcomes.

Is deoxycholic acid able to reduce submental fat and increase patient satisfaction when compared to placebo groups? A systematic review.

The accumulation of submental fat (SMF) can negatively impact facial harmony appearance, and one alternative treatment for this condition is the application of deoxycholic acid (DOC). The objective of this systematic review was to answer the following question: "Is DOC able to reduce SMF and increase patient satisfaction when compared to the placebo groups?". Therefore, a detailed search strategy was carried out in 6 scientific databases (PubMed, Scopus, Embase, Lilacs, SciELO, and Web of Science) as primary search sources, while OpenGrey and OpenThesis were also used to capture the "grey literature". Only six studies met all inclusion criteria and were considered in this review analysis. The selected sample included prospective clinical studies published from 2014 to 2018, covering a total sample of 3488 patients, with an average age ranging from 46 to 49.5 years old. All selected articles evaluated the effect of DOC at concentrations of 1 mg/cm² or 2 mg/cm², using saline or placebo as control solutions for the comparative analysis. The application interval was 28 days in all studies analyzed, and the treatment duration ranged from 4 to 6 weeks. In all studies evaluated, there was a reduction in SMF and patient satisfaction with the application of DOC was higher than in the control groups at the end of a 12-week period. Thus, it is possible to conclude that the application of DOC has a positive effect on reducing SMF and improving patient satisfaction concerning their facial appearance.

Evaluation of deviation in implants placed at different depths with a prototype surgical guide: an in vitro study.

The aim of this study was to measure the angular and linear deviations between planned and placed dental implant positions at different depths in an in vitro model. Ten dental manikins of a maxilla without the central and lateral incisors were used. The implants were placed in the tooth positions using a prototype guide based on computed tomographic scans of dental casts. The groups consisted of implants placed at varying depths according to tooth position: 1 mm deep for the right lateral incisor, 2 mm deep for the right central incisor, 3 mm deep for the left central incisor, and 4 mm deep for the left lateral incisor (n = 10 per group). After implant placement, the manikin was scanned again to compare the positioning of the implants to the planned positions. Statistical analysis evaluated the linear deviations between planned and placed implant positions at 3 points (coronal, central, and apical) as well as the angular discrepancies. The analysis showed that the depth of the implant placement proportionally affected the linear deviation of the actual position from the planned position; thus, the deeper implants showed significantly greater linear deviations (P < 0.05; 1-way analysis of variance and Tukey test). There were no statistically significant differences in the mean angular deviations of the groups. Thus, the results suggest that implants placed at greater depths present greater linear deviations than implants placed at shallower depths, but the angular deviation is not affected by implant depth.

Botulinum Toxin Injections as an Adjunct to Surgical Lip Repositioning For Gummy Smile Treatment.

BACKGROUND: An attractive smile depends on the proper proportion and arrangement of lip, teeth gingiva scaffold. The ideal smile is the exposure of the entire length of maxillary teeth with 1 mm gingiva. A gingival display exceeding 3 mm is unpleasant and termed ''gummy smile (GS).'' Lip repositioning is a simple surgical procedure intended to minimize the gingival display by removing a strip of mucosa and shortening the vestibular depth. Botulinum toxin injecting overactive muscles with measured quantities results in a reduction of muscle activity, relaxing the lip muscles and decreasing upward pull on the lip. There are some contraindications: patients with short lips and gingival exposures less than 3 mm. PURPOSE: This case report describes the successful management of GS of a young man. CASE REPORT: The procedures were performed and these techniques resulted in shortened vestibule and restricted the muscle pull of the elevator muscles of the lip, reducing gingival display when the patient smiles. Surgical lip repositioning can be a minimally invasive alternative to orthognathic surgery. Botulinum Toxin injections can be a useful adjunct to enhance the esthetics and improve patient satisfaction, being a more conservative and immediate nonsurgical treatment modality available. CONCLUSIONS: In this way, the clinical case report demonstrated that lip repositioning surgery combined to botulinum toxin injections promising outcomes in the GS correction. The effect showed a marked reduction in gingival display at the 4-years follow-up.

Stability of mandibular implants with Morse taper and external hexagon connections placed under immediate loading: a longitudinal clinical study.

The aim of this study was to compare the longitudinal stability of implants with Morse taper and external hexagon connections placed in the anterior mandible and subjected to immediate functional loading. Nine patients each received 4 mandibular implants placed between the mental foramina. In each patient, 2 implants on the left side of the arch had Morse taper prosthetic connections, and 2 implants on the right side had external hexagon prosthetic connections. Mandibular overdentures and opposing removable complete dentures were placed within 72 hours after implant surgery. Clinical evaluation of the implants via magnetic transduction resonance frequency analysis was performed immediately following surgery and 3 months, 6 months, and 2 years following surgery to obtain the implant stability quotient (ISQ). The data obtained were parametric according to the Kolmogorov-Smirnov normality test. The lowest ISQ of any implant was approximately 67, representing reliable osseointegration. The only statistically significant difference between the 2 types of prosthetic connection was found in the initial period (immediately following surgery), when the external hexagon connection in the distal position presented greater stability than did the Morse taper connection in the same position on the opposite side (P < 0.05; Student t test). In intragroup comparisons, no statistically significant differences were found regarding the positions of the implants in the mandible. When the different follow-up periods were evaluated, there were statistically significant differences only in the external hexagon group, with significant reductions in stability of both mesial and distal implants at 6 months compared to other time periods (P < 0.05; Tukey test). Within the limitations of the study, it can be concluded that both Morse taper and external hexagon prosthetic connections provide good stability in an immediate functional loading protocol.

Effect of S53P4 bioactive glass and low-level laser therapy on calvarial bone repair in rats submitted to zoledronic acid therapy.

PURPOSE: To evaluate the influence of bioactive glass and photobiomodulation therapy (PBMT) in calvarial bone repair process in rats submitted to zoledronic acid therapy. METHODS: Twenty-four rats were selected and treated with the dose of 0.035 mg/kg of zoledronic acid every two weeks, totalizing eight weeks, to induce osteonecrosis. After the drug therapy, surgical procedure was performed to create 5-mm diameter parietal bone defects in the calvarial region. The rats were then randomly assigned to groups according to the following treatments: AZC: control group, treated with blood clot; AZBIO: bone defect filled with bioactive glass; AZL: treated with blood clot and submitted to PBMT; and AZBIOL: treated with bioactive glass S53P4 and submitted to PBMT. Tissue samples were collected and submitted to histomorphometric analysis after 14 and 28 days. RESULTS: At 14 days, bone neoformation in the AZBIO (52.15 ± 9.77) and AZBIOL (49.77 ± 13.58) groups presented higher values (p ≤ 0.001) compared to the AZC (23.35 ± 10.15) and AZL groups (23.32 ± 8.75). At 28 days, AZBIO (80.24 ± 5.41)still presented significant higher bone recovery values when compared to AZC (59.59 ± 16.92)and AZL (45.25 ± 5.41) groups (p = 0.048). In the 28-day period, the AZBIOL group didn't show statistically significant difference with the other groups (71.79 ± 29.38). CONCLUSIONS: The bioactive glass is an effective protocol to stimulate bone neoformation in critical defects surgically created in rats with drug induced osteonecrosis, in the studied periods of 14 and 28 days.

Is interdental papilla filling using hyaluronic acid a stable approach to treat black triangles? A systematic review.

PURPOSE: To evaluate the stability of interdental papilla filling using hyaluronic acid (HA) to treat black triangles in esthetic regions. METHODS: The protocol was registered in PROSPERO. Six databases (PubMed, Scopus, Embase, Lilacs, SciELO, and Web of Science) were used as primary search sources, and OpenGrey and OpenThesis were used to capture the "gray literature." Only before-after studies were included. The JBI Checklist assessed the risk of bias. Only four studies met the inclusion criteria and were considered for the analyses. The studies were published from 2010 to 2016. All studies presented a low risk of bias. Considering the studies do not have control groups, a weighted average by sample size was calculated to obtain a general estimate of the percentage of papillary filling after 6 months and the number of HA applications. RESULTS: The studies showed the percentage of papillary reconstruction after 6 months of application, the weighted average by sample size was 77.41% (SD = 20.68), with an average number of applications of 3.17 (SD = 0.31). CONCLUSION: The application of HA may be used to repair anesthetic defects in the papilla. CLINICAL SIGNIFICANCE: Interdental papilla reconstruction with injectable HA is an option of nonsurgical treatment for interdental papilla deficiencies. However, there is still concern about the quality of the evidence available, considering that studies with different experimental designs can produce contradictory results. Moreover, further understanding is required on the stability of tissue gain promoted by HA in black triangles.

Hospital Intervention in Severe Sinus Infection After Bone Graft.

This study presents the case of a patient who required antrostomy under general anesthesia to treat a sinus lift complication. The patient was a 43-year-old woman with no systemic abnormalities who underwent maxillary sinus lift surgery associated with mineralized bovine bone graft. The Schneiderian membrane was perforated during the procedure, and the rupture was treated with collagen membranes to close the wound and contain the biomaterial, preventing its dispersion. The patient developed a maxillary sinus infection 7 days after surgery. This infection was initially treated with 875 mg amoxicillin combined with 125 mg clavulanic acid. Although the initial infection did not worsen, the patient developed maxillary sinusitis. Thirty days after the onset of the initial infection, the patient underwent an intraoral surgery under local anesthesia to remove the biomaterial and clean the sinus cavity. Despite this procedure, maxillary ostial patency was still compromised, and antrostomy was performed endoscopically in a hospital setting under general anesthesia. This procedure resolved the sinus infection. Then, 12 months after hospitalization, the patient was treated with another sinus graft surgery without postoperative complications. The treatment of sinus infections caused by the graft surgery may require early and active intervention with antibiotics, graft removal, and antrostomy to prevent major complications.

Computer guided surgery in the maxillary esthetic zone / Cirurgia guiada por computador em área estética da maxila

ABSTRACT This clinical report describes the implant rehabilitation for the treatment of pathological roots resorption due to inadequate orthodontic movement in prosthetic space reduced by means of load and immediate implants, computer-guided surgery and use of the own tooth crown in a 21-year-old-patient. The atraumatic exodontics of the right and left upper lateral incisors was performed, and then immediate placement of osseointegrated implants using the computer guided surgery technique. The crown teeth itself was used in the immediate aesthetic and functional rehabilitation. Completion of the treatment resulted in a functional and aesthetic successful outcome and a 27 months follow-up presented uneventful. The procedures included in this complex rehabilitation treatment in the esthetic zone were appropriate and essential for the maintenance of the soft and hard tissues contour and thickness ensuring the excellence in rehabilitation.

RESUMO Este relato de caso clínico descreve a reabilitação com implantes para o tratamento da reabsorção radicular patológica devido à movimentação ortodôntica inadequada em espaço protético reduzido, por meio implante imediato e carga imediata, pela técnica da cirurgia guiada por computador e uso da própria coroa dentária, em paciente de 21 anos. A exodontia atraumática dos incisivos laterais superiores direito e esquerdo foi realizada, em seguida realizou-se a instalação imediata dos implantes osseointegráveis, utilizando a técnica de cirurgia guiada por computador. Os próprios dentes da coroa foram usados na reabilitação estética e funcional imediata. A conclusão do tratamento resultou em sucesso funcional e estético com acompanhamento de 27 meses sem intercorrências. Os procedimentos incluídos neste complexo tratamento de reabilitação na zona estética foram adequados e essenciais para a manutenção do contorno e espessura dos tecidos moles e duros garantindo a excelência na reabilitação.

Incidence of surgical and prosthetic complications in total edentulous patients rehabilitated by the All-on-Four® technique: a retrospective study

ABSTRACT: Objective: To analyze the level of survival and the main complications presented by total edentulous patients after the All-on-Four® treatment, through a retrospective analysis. Methods: The medical records of 32 rehabilitated patients, between 2010 to 2018 were selected, presenting a total of 128 implants with subsequent fixed prostheses. The following variables were analyzed: gender, age, patient's systemic condition, time of implant installation, number of implants, and surgical and prosthetic complications. Results: The procedures were performed over on average 5.9 years ago and were more prevalent in female patients(59.6%). Out of the 32 patients selected 75% presented some systemic alteration, with hypertension being the most frequent disease. Regarding the implant placement, the rehabilitation in the mandible was more prevalent(62.5%), while in the maxilla(31.2%), and in the bimaxillary region(6.25%). As for the complications, out of 128 implants installed, 13 presented loss of osseointegration, leading to a survival rate of 90.44% (94.3% mandible and 83.3% maxilla). Furthermore, 15 surgical and 20 prosthetic complications were diagnosed. Among the surgical complications, the most frequent were loss(5-33%) and bone fracture(3-20%), while the most frequent prosthetic complications included loosening and/or or fracture of the prosthetic component and prosthetic fracture (6-30%). Conclusion: All-on-Four® is a procedure that has a high survival rate.

Survival of short dental implants in atrophied jaw: a systematic review

AIM: Short implants are manufactured for use in atrophic regions of the jaw. Therefore, the current does not sufficiently reveal a direct correlation between the impact of implant length on implant survival. The purpose of this systematic review was to compile the evidence of short implant survival in atrophied jaws. METHODS: Electronic and manual literature searches were performed by two independent reviewers in several databases, including MEDLINE, EMBASE, and Cochrane Oral Health Group Trials Register, for articles up to September 2015 using the following terms in some combinations: "short implant", "mandible/atrophied jaws", and "implant survival/ survival rate/ survival analysis". RESULTS: The 19 included studies present in average 5.5 years (range 1.0-20.0 years) follow-up and 96.1% (range 73.4-100.0 percent) survival rate of the short implants in atrophied mandibular. CONCLUSIONS: This systematic review found evidences regarding to safety of short implant placement in atrophied jaws although stronger evidence is essential to confirm this finding.

Is Low-Level Laser Therapy Effective for Pain Control After the Surgical Removal of Unerupted Third Molars? A Randomized Trial.

PURPOSE: One of the main challenges after extraction of unerupted third molars is pain control, and one of the treatments for pain control is low-level laser therapy (LLLT). Thus, this study aimed to assess the effectiveness of LLLT for pain control after extraction of lower third molars. MATERIALS AND METHODS: This randomized, double-blind, split-mouth study included patients who required bilateral extraction of unerupted lower third molars. Patients received LLLT on 1 side (laser group) but not on the opposite side (control group). On the experimental side, each patient received a laser application at 5 intraoral points for 30 seconds per point. This procedure was simulated on the control side. The pain control response was assessed with a modified pain visual analog scale at the following times: immediately after surgery (T0), after laser application (T1), 24 hours after surgery (T2), 48 hours after surgery (T3), and 72 hours after surgery (T4). RESULTS: Thirty-two patients, 56.25% of whom were women, underwent extraction; the average age was 22.2 years. At the times analyzed, the laser group presented better results than the control group. As for the times, there were differences in pain scores between T0 (8.03 ± 14.87) and T3 (2.66 ± 4.23), as well as T4 (3.36 ± 7.83), in the laser group and differences between T0 (19.76 ± 26.66) and T3 (7.11 ± 10.76), as well as T4 (6.26 ± 13.14), in the control group. CONCLUSION: LLLT was effective in reducing pain after surgical removal of unerupted third molars. At T3 and T4, pain reduction in relation to T0 was noted in both groups.

Hyaluronic acid for repairing interdental papilla in esthetic area: case report

ABSTRACT: Background: Hyaluronic acid is a treatment option for this deficiency gingival papilla, since it aims to increase tissue volume in the region of loss of interdental papilla, minimally invasive. Aim this study was to describe the application of Hyaluronic acid in a deficient gingival papilla. Case report: Patient presented absence of interdental papilla in the maxillary arch around upper anterior teeth. A comprehensive exam was performed, plus 2D photographs taken with a professional camera coupled to a device for image standardization, and an intraoral scanning with the OMNICAM scanner. Three applications of Hyaluronic acid were performed to fill the black spaces, at an interval of four weeks. The patient was followed-up for three months, and the recovery of papilla was observed. Conclusion: The Hyaluronic acid as gingival filling material can be considered as a treatment option for augmenting interdental papilla in aesthetic area.

Gingival Melanin Depigmentation With Diode Laser - Case Report / Despigmentación Melánica Gingival con Láser de Diodo - Relato de Caso

ABSTRACT: The pigmented lesions of the oral cavity may be endogenous or exogenous. Endogenous lesions are benign and usually caused by melanin, and they are called gingival melanin pigmentations. Among the options for depigmenting these areas, laser therapy stands out for being a minimally invasive procedure. This study aims to report a clinical case of the gingival depigmentation technique using a high-power diode laser in the anterior maxillary region, for the ablation of the pigmented tissue to improve gingival aesthetics. The patient had an aesthetic complaint of the darkened aspect of the gingiva in the anterior maxillary and mandibular portions. After local anesthesia, we started depigmentation with high-power diode laser and performed ablation from the attached gingiva toward the free marginal gingiva. The patient returned after 30 and 180 days presenting healthy gingiva and absence of melanin repigmentation. Thus, we concluded that the diode laser was a good alternative for melanin depigmentation because it is a procedure with lower morbidity and satisfactory postoperative results.

RESUMEN: Las lesiones pigmentadas de la cavidad oral pueden ser endógenas o exógenas. Las endógenas son benignas y generalmente causadas por la melanina, denominándose pigmentaciones melánicas gingivales. Entre las opciones para la despigmentación de estas regiones, se destaca la laserterapia, por ser un procedimiento poco invasivo. Este trabajo tuvo como objetivo relatar un caso clínico de la técnica de despigmentación gingival utilizando láser de diodo de alta intensidad en la región anterior de los maxilares para ablación del tejido pigmentado con la finalidad de mejorar la estética gingival. El paciente presentaba como queja estética el aspecto oscurecido de la encía en la región anterior de la maxila y de la mandíbula. Tras aplicar anestesia local, se inició la despigmentación con láser de diodo de alta intensidad, siendo que la ablación se realizó a partir de la encía insertada hacia la encía marginal libre. El paciente regresó tras 30 y 180 días, presentando encía saludable y con ausencia de repigmentación melánica. Así fue posible concluir que el láser de diodo mostró ser una buena alternativa para la despigmentación melánica, ya que se presentó como un procedimiento con menor morbidad y buen resultado postoperatorio.

Human non-decalcified histology of three dental implants 45 months under function-a case report.

BACKGROUND: Fracture of an implant is a quite rare event but represents an important opportunity to evaluate the peri-implant bone tissue response to implant overload in human beings. This study aimed to evaluate bone tissue around three fractured titanium implants retrieved from a human maxilla, by histomorphometric and birefringence analyses. CASE REPORT: For this, the implants and the surrounding bone were removed after having been united to a tooth in function for 45 months, by a 4-mm internal diameter trephine bur, following an undecalcified section was obtained. The results showed a rate of 77.3% of bone-to-implant contact (BIC) and 80.3% of bone area filling within the limits of the implant threads. Under circularly polarized light microscopy investigation, the amount of the transverse collagen fibers was of 48.11%, and the amount of the longitudinal collagen fibers was of 51.89%. CONCLUSION: Within the limitation of this study, the possible cause of the implant fracture could be the association of overload, inadequate implant diameter, and fragile internal hexagon connection.

Effect of low-level laser therapy and zoledronic acid on bone repair process.

This study aimed to evaluate, through histomorphometric analysis, the bone repair process in the tibia of rats treated with zoledronic acid and submitted to 808-nm low-level laser therapy (LLLT) by using arsenide aluminum gallium laser. For this purpose, 20 rats were used and distributed according to treatment: group 1-saline administration; group 2-treated with LLLT; group 3-treated with zoledronic acid; and group 4-treated with zoledronic acid and LLLT. The zoledronic acid was administered at a dose of 0.035 mg/kg every 2 weeks for 8 weeks. Subsequently, bone defects of 2 mm were prepared in the tibias of all groups. The bone defects in groups 2 and 4 were irradiated with LLLT in the immediate post-operative period. After 14 and 28 days of application, the animals were submitted and euthanized for histomorphometric analysis. The results were submitted to statistical analysis (α = 5%), and the intragroup comparison was performed using the t test. On the other hand, for intergroup comparison, the ANOVA test was performed, and to the groups presenting statistically significant difference, the Student-Newman-Keuls test was used. In intergroup comparison, group 1 (mean ± SD= 45.2 ± 18.56%) showed a lower bone formation compared with groups 2 (64.13 ± 3.51%) (p = 0.358) and 4 (15.2 ± 78.22%) (p = 0.049), at the 14-day period. Group 3 (20.99 ± 7.42%) also presented a lower amount of neoformed bone tissue, with statistically significant difference when compared with groups 1 (p = 0.002), 2, and 4 (p ≤ 0,001). After 28 days, group 1 presented a lower amount of neoformed bone tissue compared with the other groups, with p = 0.020. Thus, it was concluded that LLLT associated with zoledronic acid is effective for stimulating bone formation in surgically created defects in rats, at the periods studied.

Morse taper performance: A finite element analysis study.

OBJECTIVES: To evaluate and compare the magnitude and distribution of stresses generated on implants, abutments and first molar metal-ceramic crowns using finite element analysis. METHODS: Preliminary three-dimensional models were created using the computer-aided design software SolidWorks. Stress and strain values were observed for two distinct virtual models: model 1 - Morse taper and solid abutment; model 2 - Morse taper and abutment with screw. A load (250 N) was applied to a single point of the occlusal surface at 15° to the implant long axis. Von Mises stresses were recorded for both groups at four main points: 1) abutment-retaining screws; 2) abutment neck; 3) cervical bone area; 4) implant neck. RESULTS AND CONCLUSION: Model 1 showed a higher stress value (1477.5 MPa) at the abutment-retaining screw area than the stresses found in model 2 (1091.1 MPa for the same area). The cervical bone strain values did not exceed 105 µm for either model.

Use of Calcium Phosphate Cement for Repairing Bone Defects: Histomorphometric and Immunohistochemical Analyses.

This study aimed to assess the repair of surgically created bone defects filled with blood clot, autogenous bone, and calcium phosphate cement, by histomorphometric and immunohistochemical analyses. Ten adult male rabbits were used. Three bone defects were prepared with an 8-mm diameter trephine bur in the parietal region of each animal and filled with blood clot (Group BC), autogenous bone (Group AB), and calcium phosphate bone cement (Group CPC). The animals were euthanized at 40 and 90 postoperative days. The sections were subjected to histomorphometric analysis of the new bone formed inside the calvarial defects and immunohistochemical staining to determine the expression of osteocalcin (OC), osteopontin (OP), and tartrate-resistant acid phosphatase (TRAP) proteins. Histomorphometric data were analyzed statistically by analysis of variance and Tukey's post hoc test at 5% significance level. In the results at 40 and 90 days, Group AB differed significantly from Group CPC regarding the area of newly formed bone. The immunohistochemical analysis revealed expression of OP, OC, and TRAP proteins in all groups. Group AB showed prevalence of OC and OP, and lower TRAP expression. Therefore, the calcium phosphate bone cement assessed in the present study did not accelerate the protein expression dynamics during bone healing, compared with the autogenous group.