An in vitro study using confocal laser scanning microscopy to evaluate the marginal misfits of different implant-supported frameworks.

PURPOSE: This study aimed to develop and evaluate a simple, non-destructive method for assessing the misfit and passivity of implant-retained prostheses frameworks. MATERIALS AND METHODS: To simulate the rehabilitation of a mandible posterior partially edentulous area using 3-unit screw-retained frameworks supported by two implants were fabricated and divided into the following five groups (n = 10 in each group): OP = one-piece framework cast in Co-Cr with the conventional method (control-group); Co-Cr frameworks sectioned and welded by laser (=LAS) or tungsten inert gas (=TIG); Co-Cr CAD-CAM = milled Co-Cr framework; Zir CAD-CAM = milled zirconia framework. The horizontal |X| and vertical |Y| misfits were measured using confocal laser scanning microscopy with one or both screws tightened. Data were analyzed by a two-way ANOVA with repeated measures and Bonferroni correction (α = 0.05). RESULTS: The greatest |X| misfit was observed in the OP group with both screws tightened (290 µm) and one screw tightened (388 and 340 µm). The conventional casting groups sectioned and welded by laser or TIG had lower mean values (235.35 µm, both screws tightened; and 275 µm, one screw tightened) than the OP framework. However, these values still exceeded those of the milled Co-Cr and zirconia frameworks (190 and 216 µm with both screws tightened). Across all reading conditions, every framework subjected to testing consistently maintained vertical |Y| misfit levels below the threshold of 53 µm; however, the milled frameworks exhibited higher vertical misfits than the frameworks obtained by the conventional cast method. CONCLUSIONS: The frameworks, whether cast and sectioned with laser welding or milled from Co-Cr, exhibit improved marginal misfit and enhanced passive fit when compared to other fabrication methods. Additionally, the use of confocal laser scanning microscopy is highly effective for passivity and misfit analysis.

The use of a mandibular repositioning device for obstructive sleep apnea.

The objective of this study was to verify the effect of a mandibular repositioning device (MRD) on polysomnographic parameters and on the mean electromyographic activity of the masseter and temporal muscles in individuals with obstructive sleep apnea syndrome (OSAS). This is a prospective cohort study conducted at multidisciplinary OSAS center in a tertiary referral center. Nineteen individuals with mild or moderate OSAS associated with Mallampati 3-4 were treated with an MRD during sleep. The subjects underwent diurnal electromyography (EM) and nocturnal polysomnography (PSG) examinations both prior and after initial treatment (3 months with MRD for PSG and 6 and 12 months of treatment for EM). The examinations performed at different times were compared. Comparison of the initial and final polysomnography examination revealed a significant mean reduction of apnea-hypopnea index (AHI) from 13.8 to 7.8. The successful treatment rate with the MRD was 52.6%, and the improved treatment rate was 68.4%. Patients with lower pre-treatment AHI presented higher rates of cure. There was no statistically significant change in electromyography examination among different times. The MRD reduced the apnea-hypopnea index in individuals with enlarged base of tongue and mild and moderate OSAS without damaging the function of the masseter and temporal muscles as determined by electromyography.

Predictors of uvulopalatopharyngoplasty success in the treatment of obstructive sleep apnea syndrome.

OBJECTIVE: Uvulopalatopharyngoplasty (UPPP) has been described as an option for treating obstructive sleep apnea syndrome (OSAS), with variable success rates. The main purpose of our study was to correlate UPPP success to craniofacial bony structure and orofacial muscles function. METHODS: Clinical variables, including body mass index (BMI), age, and preoperative apnea-hypopnea index (AHI); cephalometric measurements of the craniofacial region and hyoid bone position; and muscle function variables including clinical protocol and tongue strength measures were evaluated in 54 patients who underwent UPPP in the last 7years. The measurements were related to the success or failure of UPPP based on the results of preoperative and postoperative polysomnography (PSG). RESULTS: The variables BMI, preoperative AHI, and cephalometric measurements showed no influence on surgical success. The clinical muscle protocol also was similar between groups. However, the muscle strength of the anterior portion of the tongue was significantly greater in the group that showed surgical success compared to those with surgical failure. CONCLUSION: OSAS is a multifactorial disease and diagnostic symptom assessments should be individualized. In addition, special attention should be given to functional muscle alterations of the airways, as they might influence the evolution of the disease.

Cephalometric evaluation of facial pattern and hyoid bone position in children with obstructive sleep apnea syndrome.

OBJECTIVES: To assess the development of face and hyoid bone in children with obstructive sleep apnea syndrome (OSAS) through lateral cephalometries. MATERIALS AND METHODS: Children aged 7-10 years with mixed dentition and with no previous otorhinolaryngologic, orthodontic or speech therapy treatments were studied. Twenty nasal breathers were compared to 20 mouth breathing children diagnosed as OSAS patients. All children underwent otorhinolaryngologic evaluation and cephalometries; children with OSAS also underwent nocturnal polysomnography in a sleep laboratory. RESULTS: Children with OSAS presented increase in total and lower anterior heights of the face when compared to nasal breathers. In addition, children with OSAS presented a significantly more anterior and inferior position of the hyoid bone than nasal breathers. No significant differences in upper, anterior or posterior heights of the face were observed between groups. CONCLUSION: The results suggest that there are evident and early changes in facial growth and development among children with OSAS, characterized by increased total and inferior anterior heights of the face, as well as more anterior and inferior position of the hyoid bone.

Physical properties of a denture base acrylic resins after incorporation of anionic chargesde radicais aniônicos / Propriedades físicas de uma resina acrílica para base de prótese após a incorporação

This study evaluated the influence of methacrylic acid (MA) incorporation on hardness, roughness, and flexural strength of a denture base acrylic resin. Thirty-two circular and 40 rectangular specimens were divided into four groups, according to the concentration of MA substituted into the monomer component of a heat-polymerized acrylic resin, as follows: 0% (Control), 10%, 20% and 50% (v/v). The following properties were assessed: Vickers hardness, surface roughness, and flexural strength. Variables were analyzed by ANOVA/Tukey’s test (α=.05). For the four incorporated MA concentrations (0%, 10%, 20% and 50%), the following results were obtained for hardness (19.0±1.4A, 19.6±1.3A, 19.6±0.9A, 14.2±0.6B VHN), surface roughness (0.26±0.05A, 0.17±0.01AB, 0.18±0.03AB, 0.13±0.03B μm) and flexural strengh (96.3±8.3A, 98.8±6.2A, 102.4±8.6A, 106.3±13.7A MPa). The incorporation of MA may cause slight changes in the structure of the tested material, as evidenced by the hardness test. However, the values for surface roughness reduced as MA concentration increased, suggesting that MA addition may improve the acrylic resin texture.

Este estudo avaliou a influência da incorporação do ácido metacrílico (AM) sobre a dureza, rugosidade e resistência flexural de uma resina acrílica para base de próteses removíveis. Trinta e dois espécimes circulares e 40 retangulares foram divididos em quatro grupos, conforme a concentração de AM substituído no componente monomérico de uma resina acrílica termopolimerizável: 0% (Controle), 10%, 20% e 50% (v/v). As seguintes propriedades foram avaliadas: dureza Vickers, rugosidade superficial e resistência flexural. As variáveis foram analisadas por meio de ANOVA seguida pelo teste de Tukey (α=0,05). Para as concentrações de AM incorporadas (0%, 10%, 20% e 50%), os seguintes resultados foram obtidos para a dureza (19,0±1,4A, 19,6±1,3A, 19,6±0,9A, 14,2±0,6B VHN), rugosidade superficial (0,26±0,05A, 0,17±0,01AB, 0,18±0,03AB, 0,13±0,03B μm) e resistência flexural (96,3±8,3A, 98,8±6,2A, 102,4±8,6A, 106,3±13,7A MPa). A incorporação do AM pode causar mudanças discretas nas propriedades estruturais do material testado, como evidenciado pelo teste de dureza. No entanto, os valores de rugosidade diminuíram em proporção ao acréscimo de AM, sugerindo que essa incorporação pode melhorar a textura da resina acrílica para base protética.