Survival of temporomandibular total joint replacement: A systematic review and meta-analysis.

BACKGROUND: Prosthetic total joint replacement has been incorporated as a treatment for complex temporomandibular disorder; however, the survival of those devices is unknown. OBJECTIVE: To assess the survival rate of the total temporomandibular joint (TMJ) prothesis and their main causes of failure. METHODS: An electronic search was conducted in eight databases until March 2023. Prospective studies reporting the survival rate of total TMJ prothesis with a minimum follow-up of 12 months were included. Studies with partial TMJ prostheses or those no longer available on the market were excluded. Two reviewers assessed the individual risk of bias using the JBI Systematic Reviews for Quasi-experimental studies tool. Meta-analysis of proportions was conducted to summarise the survival rate, using 95% confidence intervals (CI). The GRADE approach assessed the certainty of the body of evidence. RESULTS: Data from 320 patients were collected from six prospective studies. The number of prothesis losses varied from none to four. All studies presented sources of bias related to follow-up description of the patients. The follow-up time varied from 12 months to 21 years. In most of the studies, prosthesis failure occurred within the first 6 months after surgery due to infection. The overall survival of total TMJ protheses was 97% (95% CI: 95%; 99%), with low heterogeneity (I2 = 29%) and a very low certainty of evidence. CONCLUSION: TMJ total prosthesis apparently is a safe procedure with a high survival rate and the evidence is very uncertain and presents important sources of bias.

Evaluation of mandibular implant-supported fixed prosthesis retained by 3 dental implants, 1 straight and 2 angled: A retrospective clinical study.

STATEMENT OF PROBLEM: The minimum number of implants to support fixed complete dentures is still unclear. PURPOSE: The purpose of this retrospective clinical study was to evaluate the survival rate of fixed complete dentures supported by 3 immediately loaded implants opposing maxillary complete dentures. MATERIAL AND METHODS: A retrospective study of edentulous patients rehabilitated with complete dentures opposing mandibular metal-resin implant-supported fixed complete dentures supported by 3 immediately loaded implants was conducted in a 48-hour protocol. Fifty-one machined and 99 rough-surface implants were evaluated from 2.2 up to 8 years. Implant loss, peri-implant outcomes, and mechanical complications were assessed by considering the influence of age, sex, health status, smoking, excessive alcohol consumption, educational level, and socioeconomic status. The presence of comorbidities in relation to the implant surface or the cantilever lengths was also evaluated. RESULTS: Four machined and 6 rough-surface implants failed, a 6.7% failure rate. The cantilever length varied from 3.3 to 22.9 mm. Mechanical complications were abutment screw loosening (3.0%), prosthetic screw loosening (17%), screw fracture (1%), superstructure detachment and fractures (16%), metal framework fracture (2%), maxillary denture fractures (6%), and mandibular prosthesis loss (4%). Peri-implant mucositis was found in 27% of participants. The cumulative implant and mandibular prosthesis survival rates were 93.3% and 96%, respectively. None of the variables evaluated, including demographic data and health status, were found to influence clinical failures and/or mechanical complications. CONCLUSIONS: Mandibular fixed complete dentures supported by 3 implants can be considered a successful treatment with reduced costs compared with those of other fixed options for application in public health.

Structural resistance of orthodontic mini-screws inserted for extra-alveolar anchorage.

The risk of fracture or strain in mini-screws is higher if diameter, length, type of alloy or insertion angle is selected inappropriately. The aims of this study were to test the structural resistance of two types of orthodontic mini-screws -one made of stainless steel and another of titanium- from an international brand and to evaluate the efficacy of two other titanium miniscrews of Brazilian origin, during an extra-alveolar anchorage procedure. The mini-screws analyzed were: Bomei stainless steel and Bomei titanium / Taiwan, Morelli titanium and Neodent titanium/ Brazil. Experiments were conducted on pig mandibles to simulate the process of extra-alveolar anchorage. Two insertion processes were used: Direct at 30º, and Indirect, starting at 60º and ending at 30º with gradual continuous movement. Strain was evaluated using Optical and Scanning Electron Microscopy. Data were evaluated using Kruskal-Wallis non-parametric statistical analysis and post hoc Tamhane test. Significant statistical differences in strain were observed among the mini-screws used in the extra-alveolar insertions, both for the direct and indirect procedures. In the indirect insertion tests, both stainless steel and titanium mini-screws suffered deformation, showing that angling can be an important factor in mini-screw failure rates. The change in angle during the insertion movement increased deformation rates independently of alloy type, increasing the risk of failure. These results could help orthodontists in choosing mini-screws for extra-alveolar anchorage, which can be performed with direct or indirect insertion. In vivo studies should be conducted to confirm the findings of this study.

O risco de fratura ou tensão nos mini-parafusos é maior se o diâmetro, comprimento, tipo de liga ou ângulo de inserção for selecionado de forma inadequada. Os objetivos deste estudo foram testar a resistência estrutural de dois tipos de miniaparafusos ortodônticos ­um feito de aço inoxidável e outro de titânio­ de uma marca internacional e avaliar a eficácia de dois outros mini-parafusos de titânio de origem brasileira, durante um procedimento de ancoragem extra-alveolar. Os miniaparafusos analisados foram: Bomei aço inoxidável e Bomei titânio / Taiwan, Morelli titânio e Neodent titânio / Brasil. Foram realizadas experiências em mandíbulas de porcos para simular o processo de ancoragem extra-alveolar. Foram utilizados dois processos de inserção (Direta a 30º, e Indireta, começando a 60º e terminando a 30º com movimento gradual contínuo). A deformação foi avaliada utilizando Microscopia Óptica e Microscopia Eletrônica de Varredura. Os dados foram avaliados utilizando análise estatística não paramétrica Kruskal-Wallis e teste post-hoc Tamhane. Diferenças estatísticas significativas na deformação foram observadas entre os miniparafusos utilizados nas inserções extra-alveolares, tanto para os procedimentos diretos como indiretos. Nos testes de inserção indireta, tanto os mini-parafusos de aço inoxidável como os de titânio sofreram deformação, mostrando que a angulação pode ser um fator importante nas taxas de falha dos mini-parafusos. A mudança no ângulo durante o movimento de inserção aumentou as taxas de deformação independentemente do tipo de liga, aumentando o risco de falha. Estes resultados podem ajudar os ortodontistas na escolha de mini-parafusos para ancoragem extra-alveolar, que pode ser realizada com inserção direta ou indireta. Estudos in vivo devem ser conduzidos para confirmar os resultados deste estudo.

Structural resistance of orthodontic mini-screws inserted for extraalveolar anchorage / Resistência estrutural de mini-aparafusos ortodônticos inseridos para ancoragem extra-alveolar

ABSTRACT The risk of fracture or strain in mini-screws is higher if diameter, length, type of alloy or insertion angle is selected inappropriately. The aims of this study were to test the structural resistance of two types of orthodontic mini-screws -one made of stainless steel and another of titanium- from an international brand and to evaluate the efficacy of two other titanium miniscrews of Brazilian origin, during an extra-alveolar anchorage procedure. The mini-screws analyzed were: Bomei stainless steel and Bomei titanium/Taiwan, Morelli titanium and Neodent titanium/ Brazil. Experiments were conducted on pig mandibles to simulate the process of extra-alveolar anchorage. Two insertion processes were used: Direct at 30°, and Indirect, starting at 60° and ending at 30° with gradual continuous movement. Strain was evaluated using Optical and Scanning Electron Microscopy. Data were evaluated using Kruskal-Wallis non-parametric statistical analysis and post hoc Tamhane test. Significant statistical differences in strain were observed among the mini-screws used in the extra-alveolar insertions, both for the direct and indirect procedures. In the indirect insertion tests, both stainless steel and titanium mini-screws suffered deformation, showing that angling can be an important factor in mini-screw failure rates. The change in angle during the insertion movement increased deformation rates independently of alloy type, increasing the risk offailure. These results could help orthodontists in choosing mini-screws for extra-alveolar anchorage, which can be performed with direct or indirect insertion. In vivo studies should be conducted to confirm the findings of this study.

RESUMO O risco de fratura ou tensao nos mini-parafusos é maior se o diámetro, comprimento, tipo de liga ou ángulo de insergao for selecionado de forma inadequada. Os objetivos deste estudo foram testar a resistencia estrutural de dois tipos de mini-aparafusos ortodónticos -um feito de ago inoxidável e outro de titànio- de uma marca internacional e avaliar a eficácia de dois outros mini-parafusos de titànio de origem brasileira, durante um procedimento de ancoragem extra-alveolar. Os mini-aparafusos analisados foram: Bomei ago inoxidável e Bomei titànio / Taiwan, Morelli titànio e Neodent titànio / Brasil. Foram realizadas experiencias em mandíbulas de porcos para simular o processo de ancoragem extra-alveolar. Foram utilizados dois processos de insergao (Direta a 30°, e Indireta, comegando a 60° e terminando a 30° com movimento gradual continuo). A deformagao foi avaliada utilizando Microscopia Optica e Microscopia Eletrónica de Varredura. Os dados foram avaliados utilizando análise estatistica nao paramétrica Kruskal-Wallis e testepost-hoc Tamhane. Diferengas estatisticas significativas na deformagao foram observadas entre os mini-parafusos utilizados nas insergoes extra-alveolares, tanto para os procedimentos diretos como indiretos. Nos testes de insergao indireta, tanto os mini-parafusos de ago inoxidável como os de titánio sofreram deformagao, mostrando que a angulagao pode ser um fator importante nas taxas de falha dos mini-parafusos. A mudanga no ángulo durante o movimento de insergao aumentou as taxas de deformagao independentemente do tipo de liga, aumentando o risco de falha. Estes resultados podem ajudar os ortodontistas na escolha de mini-parafusos para ancoragem extra-alveolar, que pode ser realizada com insergao direta ou indireta. Estudos in vivo devem ser conduzidos para confirmar os resultados deste estudo.

Magnetic resonance imaging evaluation of articular disk position after orthognathic surgery with or without concomitant disk repositioning: a retrospective study.

OBJECTIVE: The aim of this study was to compare the outcomes of 2 surgical treatment options: one for correction of class II malocclusion skeletal deformity and one for pre-existing temporomandibular joint (TMJ) disorders requiring orthognathic surgery (OS) for correction of dentofacial deformity. STUDY DESIGN: This retrospective study evaluated patients who underwent OS with maxillomandibular advancement (MMA) with or without concomitant TMJ surgery for articular disk repositioning (ADR). Patients were divided into 2 groups: group I (MMA) was treated with OS only (18 patients); and group II (MMA-ADR) was treated with OS and concomitant ADR (19 patients). The sample consisted of 74 TMJs (mean patient age 29.86 years). RESULTS: In group I, 38.5% of the disks that were originally in normal position became displaced after OS, and 33.3% of displaced disks with reduction became nonreducing after OS. In group II, 78.9% of disks exhibited normal position in the final evaluation, and 97.3% of patients showed improved disk position after surgery. There was significant symptom improvement in all patients in group II, but no significant improvement in group I. CONCLUSIONS: OS with ADR appears to produce stable and beneficial results in improving symptoms in patients with displaced disk and TMJ pain.

Biomechanical and morphological changes produced by ionizing radiation on bone tissue surrounding dental implant.

OBJECTIVE: This study analyzed the effect of ionizing radiation on bone microarchitecture and biomechanical properties in the bone tissue surrounding a dental implant. METHODOLOGY: Twenty rabbits received three dental morse taper junction implants: one in the left tibia and two in the right tibia. The animals were randomized into two groups: the nonirradiated group (control group) and the irradiated group, which received 30 Gy in a single dose 2 weeks after the implant procedure. Four weeks after the implant procedure, the animals were sacrificed, and the implant/bone specimens were used for each experiment. The specimens (n=10) of the right tibia were examined by microcomputed tomography to measure the cortical volume (CtV, mm3), cortical thickness (CtTh, mm) and porosity (CtPo, %). The other specimens (n=10) were examined by dynamic indentation to measure the elastic modulus (E, GPa) and Vickers hardness (VHN, N/mm2) in the bone. The specimens of the left tibia (n=10) were subjected to pull-out tests to calculate the failure load (N), displacement (mm) up to the failure point and interface stiffness (N/mm). In the irradiated group, two measurements were performed: close, at 1 mm surrounding the implant surface, and distant, at 2.5 mm from the external limit of the first measurement. Data were analyzed using one-way ANOVA, Tukey's test and Student's t-test (α=0.05). RESULTS: The irradiated bone closer to the implant surface had lower elastic modulus (E), Vickers hardness (VHN), Ct.Th, and Ct.V values and a higher Ct.Po value than the bone distant to the implant (P<0.04). The irradiated bone that was distant from the implant surface had lower E, VHN, and Ct.Th values and a higher Ct.Po value than the nonirradiated bone (P<0.04). The nonirradiated bone had higher failure loads, displacements and stiffness values than the irradiated bone (P<0.02). CONCLUSION: Ionizing radiation in dental implants resulted in negative effects on the microarchitecture and biomechanical properties of bone tissue, mainly near the surface of the implant.

Does the natural maxillary dentition influence the survival rate of mandibular metal-resin implant-supported fixed complete dentures? A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Consensus is lacking regarding the influence of the maxillary dentition on the survival rate of a mandibular metal-resin implant-supported fixed complete denture (MRISFCD) with distal cantilevers. PURPOSE: The purpose of this systematic review was to identify whether an opposing natural dentition influences the survival rate of mandibular MRISFCDs. MATERIAL AND METHODS: A literature search was performed up to February 2018 from MEDLINE/PubMed, Scopus, Web of Science, Cochrane Library, BBO/LILACS databases and also in the non-peer-reviewed literature through Open Grey. Clinical studies regarding natural (ND), removable prostheses (RP), and complete fixed maxillary implant dentitions (ID) with at least a year of follow-up were included. The quality of the included studies was analyzed, and the risk of bias was reported. A meta-analysis comparing the survival rate of ND with RP and ND with ID was performed with a confidence interval (CI) of 95%, and heterogeneity was tested by an I2 index. Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach was used to determine the certainty of the evidence. RESULTS: From a total of 112 ND, 69 ID, and 204 RP in the maxillary dentition, the overall prevalence of failures was 5.4% (6/112; 95% CI [2.3 to 10.76]) for ND, 13.99% (20/69; 95% CI [0.77 to 39.41]) for ID, and 4.9% (10/204; 95% CI [0.69 to 12.18]) for RP. No statistical differences were detected in the success rates between ND and RP (risk difference = 0.00 [-0.06, 0.06]; P=.93; I2=27%) or between ND and ID (risk difference=0.00 [-0.06, 0.07]; P=.97; I2=0%), both with moderate evidence. CONCLUSION: With a moderate certainty of evidence, it is suggested that natural maxillary dentitions do not affect the survival rate of mandibular MRISFCDs differently from other prosthetic designs.

Effect of ionizing radiation after-therapy interval on bone: histomorphometric and biomechanical characteristics.

OBJECTIVES: This study aimed to evaluate the effects of radiotherapy on biomechanical, histomorphometric, and microstructural characteristics of bone, in diverse periods, compared with intact bone tissue. MATERIALS AND METHODS: Eighteen adult male New Zealand rabbits were treated with a single radiation dose of 30 Gy. The animals were randomly divided into six groups: NoIr, control group, no radiation, and five irradiated groups sacrificed after 24 h (Ir24h), 7 (Ir7d), 14 (Ir14d), 21 (Ir21d), and 28 (Ir28d) days. After these periods, the animals were sacrificed and their tibias (n = 6) evaluated using three-point bending test to calculate the ultimate force, work to failure, and bone stiffness. Dynamic indentation test was used to quantify Vickers hardness and elasticity modulus of bone tissue. Micro-CT was used to analyze the cortical volume (CtV), cortical thickness (CtTh), and porosity (Ct.Po). Histomorphometric assessment was based on the lacunarity of bone tissue. Data were analyzed using one-way ANOVA and Kruskal-Wallis tests followed by Tukey, Dunnet, and Dunn's post-tests (P < 0.05). RESULTS: The ultimate force, work to failure, stiffness, elastic modulus, and Vickers hardness values of irradiated bone were significantly lower that non-irradiated bone. Irradiated bone showed significantly lower CtTh and CtV values and higher CtPo than non-irradiated bone. No significant difference was found for lacunarity between non-irradiated bone and irradiated bone. CONCLUSIONS: Ionizing radiation decreases normal anisotropy on microarchitecture of cortical bone, and increases bone fragility compared with non-irradiated bone. Further, these changes were seen after longer periods (e.g., 14 and 21 days), and not immediately after radiation therapy. CLINICAL RELEVANCE: The radiotherapy reduces bone mechanical properties and the normal structure of organic and inorganic bone matrix. For studying the protocols to protect the radiotherapy effect using rabbit model, the use of the sacrificing period between 14 and 21 days is recommended.

Excisional Biopsy of the Pyogenic Granuloma in Very High-Risk Patient.

Oral surgery to remove pyogenic granuloma in a high-risk patient is reported. A 47-year-old man with gastroesophageal reflux disease, diabetes mellitus II, dyslipidemia, and chronic coronary insufficiency (myocardial infarction within 2 years) with episodes of unstable angina was submitted to an excisional biopsy of hemorrhagic lesion in the lingual right mandibular gingiva. During dental treatment, the arterial blood pressure, oxygen saturation, heart rate, and electrocardiogram were monitored. Local anesthesia was performed with 0.45 ml of 3% prilocaine with 0.03 IU/ml felypressin. The anticoagulant therapy was not interrupted. No local or systemic complications were noticed during or after the surgery.

Effect of titanium surface functionalization with bioactive glass on osseointegration: An experimental study in dogs.

PURPOSE: The purpose of this study was to evaluate the effect of surface functionalization with bioactive glass BSF18 on the osseointegration of sandblasted and dual acid-etched surface (AE) implants. METHODS AND MATERIALS: Forty Morse taper implants with an AE surface as controls (C) or with an AE surface functionalized with BSF18 (BF) were placed in the mandibles of 10 beagles. Implants were analyzed after 2 and 4 weeks of healing. Implant stability quotient (ISQ) values were registered immediately after installation and prior to sacrifice. Samples were analyzed for bone-to-implant contact (BIC) and bone density (BD). The characterization of BF implants included surface roughness analysis with atomic force microscopy and contact angle (CA) analysis to evaluate wettability. Data were analyzed using two-way ANOVA followed by Tukey's test (p < 0.05). RESULTS: Surface roughness was not affected by BF treatment. CA was lower in the BF group compared to the C group. No significant difference was observed in ISQ values between surfaces (p = 0,231), irrespective of time. Significantly higher ISQ values were observed for both implants after 4 weeks when compared with baseline (p = 0.04). Significantly higher BIC (p = 0.011) and BD (p = 0.025) values were observed for the BF compared to the C group at 2 weeks. Significantly higher BIC (p = 0.030) and BD (p = 0.015) values for the C group were observed at 4 weeks compared to 2 weeks. No significant difference was observed in the BF group between 2 and 4 weeks. CONCLUSIONS: Implant functionalization with BSF18 improved the wettability of the implant surface; enhancing BIC and BD at 2 weeks.

Interfacial biomechanical properties of a dual acid-etched versus a chemically modified hydrophilic dual acid-etched implant surface: an experimental study in Beagles.

BACKGROUND: The high survival clinical success rates of osseointegration are requisites for establishing a long-term biomechanical fixation and load-bearing potential of endosseous oral implants. The objective of this preclinical animal study was to evaluate the effect of surface microtopography and chemistry on the early stages of biomechanical rigidity with a sandblasted, dual acid-etched surface, with or without an additional chemical modification (SAE-HD and SAE, respectively), in the tibia of Beagle dogs. METHODS: Two pairs of implants, with the same macrogeometry but different surface technology ((a) dual acid-etched surface treatment with hydrochloric and sulfuric acid followed by microwave treatment and insertion in isotonic saline solution to increase hydrophilicity (SAE-HD) (test, n = 12) and (b) dual acid-etched surface (SAE) (control, n = 12)), were installed bilaterally in the proximal tibia of six Beagle dogs. In order to determine the effect of surface modification on biomechanical fixation, a test protocol was established to assess the torque and a complete set of intrinsic properties. Maximum removal torque (in N cm) was the primary outcome measure, while connection stiffness (N cm/rad) and removal energy (× 10-2J) were the secondary outcome measures and were assessed after 2 and 4 weeks in vivo. A general linear statistical model was used and performed for significant differences with the one-way ANOVA followed by Tukey post hoc test (P < 0.05). RESULTS: The removal torque values did not reveal significant statistical differences between SAE-HD and SAE implants at any observation times (P = 0.06). Although a slight increase over time could be observed in both test and control groups. SAE-HD showed higher removal energy at 4 weeks (999.35 ± 924.94 × 10- 2 J) compared to that at 2 weeks (421.94 ± 450.58 × 10- 2 J), while SAE displayed lower values at the respective healing periods (P = 0.16). Regarding connection stiffness, there were no significant statistical differences neither within the groups nor over time. There was a strong, positive monotonic correlation between removal torque and removal energy (=0.722, n = 19, P < 0.001). CONCLUSIONS: In this study, no significant differences were observed between the specific hydrophilic (SAE-HD) and hydrophobic (SAE) surfaces evaluated, in terms of biomechanical properties during the early osseointegration period.

Influence of Platelet-Poor Plasma on Angiogenesis and Maintenance of Volume in Autogenous Bone Grafts.

PURPOSE: The aim of this study was to evaluate the effect of different storage media on angiogenesis and maintaining autogenous bone graft volume in rabbits. MATERIAL AND METHODS: Two grafts were removed bilaterally from the calvaria of 18 rabbits. One graft was removed and immediately fixed in the right mandibular angle (control group). The other graft was stored for 30 minutes in 1 of the following storage media (n = 6): saline solution (saline group), air exposure (dry group), or platelet-poor plasma (PPP group) and then retained by a screw in the right mandibular angle in the same animal. Four weeks later the animals were euthanized, and the grafted areas were harvested, fixed in 10% phosphate buffered formaldehyde solution, and embedded in paraffin. The 5-µm semi-serial sections were stained in hematoxylin and eosin and Mallory trichrome. RESULTS: Histologic analysis of all groups showed the bone graft was vascularized and well incorporated into the recipient site. The number of blood vessels decreased in the saline and dry groups compared with the control group (P < .03); in contrast, the number of blood vessels increased in the PPP group (P < .05). There were fewer osteoclasts in the saline group compared with the control group (P < .05). Furthermore, the saline group showed larger numbers of blood vessels than the dry group (P < .01). The PPP group showed larger bone graft volumes compared with the dry and saline groups (P < .01). In addition, the saline group showed larger bone graft volumes than the dry group (P < .01). CONCLUSIONS: PPP improved angiogenesis, maintained the volume of the autogenous bone graft, and was a better storage medium during the trans-surgical period than the dry and saline media.

Mandibular dislocation after stroke: an uncommon sequelae / Luxação mandibular após acidente vascular cerebral: uma sequela incomum

Temporomandibular joint (TMJ) recurrent dislocation is usually associated with jaw hypermobility or articular eminence anatomy. Patients who have stroke experience (CVA) can present joint and muscle tone changes, as laxity ligamentous and appearance of spastic muscle patterns in different parts of the body such as shoulder, elbow, wrist, hip, knee and face. This study reported two cases of patients with stroke sequelae who developed chronic dislocation of the jaw. It was concluded that these two clinical conditions appear to have some correlation, further studies with more patients needed to confirm this correlation.

A luxação recorrente da articulação temporo-mandibular ocorre quando o côndilo mandibular move-se para fora da cavidade glenóide e permanece travado anteriormente à eminência articular de forma repetitiva. Pacientes com histórico de acidente vascular cerebral podem apresentar alterações articulares e de tonicidade muscular. O presente estudo relatou dois casos clínicos de pacientes com seqüela de AVC, que desenvolveram luxação crônica da mandíbula. Concluiu-se que essas duas condições clinicas parecem apresentar alguma correlação clínica, sendo ainda necessário estudos com mais pacientes para confirmar tal correlação.

Histomorphometric evaluation of a dual acid-etched vs. a chemically modified hydrophilic dual acid-etched implant surface. An experimental study in dogs.

OBJECTIVE: The aim of this preclinical in vivo study was to compare histologically and histomorphometrically osseointegration of dual acid-etched vs. hydrophilic implants. MATERIAL AND METHODS: Two pairs of implants (Neodent, Curitiba, Brazil), with same macrogeometry but different surface technology (i) dual acid-etched surface (SAE) treatment with hydrochloric and sulfuric acid followed by microwave treatment and insertion in isotonic saline solution to increase hydrophilicity (SAE-HD) (test, n = 12); (ii) dual SAE (control, n = 12) were installed bilaterally in the proximal tibia of six beagle dogs. Histologic and histomorphometric evaluation was performed after 2 and 4 weeks in vivo, on non-decalcified sections. Percentages of bone-to-implant contact (BIC) and bone density (BD) were estimated and tested for significant differences with the Wilcoxon signed-rank test for paired samples (P < 0.05). RESULTS: In general, new bone formation along and in contact with the implant surface could be observed irrespective of the experimental group and observation period. Most of the bone was woven but small quantities of lamellar bone, mainly in close proximity to the cortex could also be observed. BIC at 2 weeks was 19.57 ± 13.57 and 20.33 ± 7.99 (P = 0.75), and at 4 weeks was 42.80 ± 14.48 and 40.25 ± 9.45 (P = 0.65) for SAE-HD and SAE implants respectively. BD at 2 weeks was 24.85 ± 16.31 and 25.66 ± 8.59 (P = 0.35) and at 4 weeks 44.13 ± 6.46 and 40.13 ± 6.46 (P = 0.25) for SAE-HD and SAE implants respectively. CONCLUSION: Bone-to-implant contact and BD increased with time in both SAE-HD and SAE implants. No significant differences were observed between the two different implant surfaces for any of the evaluated parameters and at any observation time-point.

Reabilitação maxilar após radioterapia utilizando implante unitário e prótese obturadora tipo overdenture: acompanhamento clínico de um ano / Maxillary rehabilitation after radiotherapy using a single-tooth dental implant and the obturator-type overdenture: one-year clinical follow-up

Este caso clínico relata o uso de uma prótese obturadora tipo overdenture para compensar a deficiência estética em um paciente previamente irradiado. Um indivíduo do sexo masculino, 73 anos de idade, que possuía uma prótese sobre três implantes dentários foi acometido de câncer no seio maxilar e assoalho da órbita. Seis doses de cisplatina e 35 sessões de radioterapia (dose diária 1,8 Gy) foram executadas. Após a maxilectomia, apenas um implante restou na região anterior. O tratamento consistiu de uma prótese obturadora tipo overdenture com encaixe tipo Equator. O paciente retornou um ano depois, sem alterações estéticas e com nível de satisfação melhorado. Entretanto, o anel borrachoide do encaixe foi trocado. Reabilitações implantossuportadas e mucorretidas que recebem carregamento tardio pode melhorar o prognóstico de implantes dentais em pacientes irradiados. Este cuidado mostra que este cenário ainda requer maior atenção da comunidade científica, na busca por meios de prevenir e minimizar os danos causados pela radioterapia, por inovações tecnológicas e protocolos regenerativos que potencializem a osseointegração. Com isso, a Odontologia poderá contribuir ainda mais com a melhora da qualidade de vida de pacientes, devolvendo satisfação pessoal e autoestima.

This case describes the use of an obturator-type overdenture prosthesis to compensate for the aesthetic defi ciency in a previously irradiated patient. A 73 years-old male, who had a prosthesis on three dental implants was diagnosed with cancer in the maxillary sinus and orbital floor. Six doses of cisplatin and 35 radiotherapy sessions (daily doses of 1.8 Gy) were performed. After maxillectomy, only one implant survived in the anterior region. The treatment consisted of an obturator overdenture with the Equator attachment. The patient returned one year later without cosmetic changes and demonstrated an enhanced satisfaction level. However, the o-ring rubber was replaced. Implant-supported, mucosa-retained restorations receiving delayed loading can improve the prognosis of dental implants in irradiated patients. Also, this scenario still requires more attention from the scientific community seeking for new ways to prevent and minimize damages caused by radiation, technological innovations, and regenerative protocols that enhance osseointegration. Thus, dentistry can further contribute to improving the quality of life of patients, returning their personal satisfaction and self-esteem.

The effects of ionizing radiation on the growth plate in rat tibiae.

The deleterious effects of ionizing radiation on the growth plate continue to be cause for concern. This study evaluated the ionizing radiation effects on bone development and growth plate in the tibia of rats. All animals were submitted to ionizing radiation on the left leg. The animals were divided into two groups and euthanized 30 and 60 days after radiation. The tibiae were removed and separated into groups: control 30 days, irradiated 30 days, control 60 days and irradiated 60 days. Animals in each group (n = 7) were used for macroscopic and histological analysis. The irradiated tibiae showed arrested growth, angular deformity and limb length discrepancy when compared with nonirradiated tibiae. There was statistical difference between control and radiation groups in all the parameters analyzed, except in the lateral-medial thickness of the distal epiphysis. Histological analysis showed evident changes in the growth plate, which was thicker in the Groups irradiated for 30 days, and irradiated for 60 days, compared with their respective controls. The growth plate showed wide areas with disorganized zones of chondrocytes and severely reduced calcification zone. It was concluded that ionizing radiation damaged the growth plate, compromised the endochondral ossification process, and resulted in complete arrest of bone development.

Influence of Implant Surfaces on Osseointegration: A Histomorphometric and Implant Stability Study in Rabbits.

The aim of this study was to evaluate the stability and osseointegration of implant with different wettability using resonance frequency analysis (RFA) and histomorphometric analysis (bone implant contact, BIC; and bone area fraction occupied, BAFO) after 2 and 4 weeks in rabbit tibiae. Thirty-two Morse taper implants (length 7 mm, diameter 3.5 mm) were divided according to surface characteristics (n=8): Neo, sandblasted and dual acid-etched; and Aq, sandblasted followed by dual acid-etched and maintained in an isotonic solution of 0.9% sodium chloride. Sixteen New Zealand rabbits were used. Two implants of each group were installed in the right and left tibiae according to the experimental periods. The RFA (Ostell(r)) was obtained immediately and after the sacrifice (2 and 4 weeks). The bone/implant blocks were processed for histomorphometric analysis. Data were analyzed using two-way ANOVA followed by Tukey's test and Pearson's correlation for ISQ, BIC and BAFO parameters (p=0.05). No significant effect of implant, period of evaluation or interaction between implant and period of evaluation was found for BIC and BAFO values (p>0.05). Only period of evaluation had significant effect for RFA values at 4 weeks (p=0.001), and at 2 weeks (p<0.001). RFA values were significantly higher at the final period of evaluation compared with those obtained at early periods. There was a significant correlation between BIC values and BAFO values (p=0.009). Both implant surfaces, Aq and Neo, were able to produce similar implant bone integration when normal cortical bone instrumentation was performed.