Influence of short-fiber composite base on fracture behavior of direct and indirect restorations.

OBJECTIVES: The aim was to examine the influence of short-fiber composite (SFC) core on the fracture-behavior of different types of indirect posterior restorations. In addition, the effect of thickness ratio of SFC-core to the thickness of the veneering conventional composite (PFC) on fracture-behavior of bi-structured composite restorations was evaluated. MATERIALS AND METHODS: MOD cavities with removed palatal cusps were prepared on 90 intact molars. Five groups of direct overlay restorations (n = 10/group) were fabricated having a SFC-core (everX Flow) with various thicknesses (0, 1, 2, 3, 4 mm) and layer of surface PFC (G-aenial Anterior), remaining the thickness of the bi-structure restoration to be 5 mm. Four groups of CAD/CAM-made restorations (Cerasmart 270 and e-max CAD) were fabricated either with 2-mm layer of SFC-core or without fiber reinforcement. Intact teeth (n = 10) were used as control group. Restorations were statically loaded until fracture. Fracture patterns were evaluated visually. Data were analyzed using ANOVA (p = 0.05). RESULTS: With indirect overlay restorations, no statistically significant differences (p > 0.05) were observed in the load-bearing capacities between restorations reinforced by 2-mm SFC-core (bi-structured) and those fabricated from plain restorative materials. ANOVA displayed that direct overlay restorations made from 4-mm layer thickness of SFC-core had significantly higher load-bearing capacities (3050 ± 574 N) (p < 0.05) among all the groups tested. CONCLUSIONS: Restorations (direct/indirect) combining SFC-core and a surface layer of conventional material demonstrated encouraging achievement in reference to fracture behavior. CLINICAL RELEVANCE: The use of flowable short-fiber composite as reinforcing base with large direct and indirect restorations may result in more repairable failure.

Factors determining COVID-19 pneumonia severity in a country with routine BCG vaccination.

BACKGROUND: The impact of countries' bacillus Calmette-Guérin (BCG) vaccination policies on the course of coronavirus disease (COVID-19) outbreak is a curiosity. In this study, the relationship between BCG vaccination status and severity of COVID-19 pneumonia and the factors affecting disease severity were investigated. METHODS: A retrospective cross-sectional study was conducted between March and June 2020 in patients diagnosed with COVID-19 pneumonia, confirmed by severe acute respiratory syndrome coronavirus-2 polymerase chain reaction positivity in a nasopharyngeal sample and pulmonary infiltrates in computed chest tomography, in a state hospital in Istanbul, Turkey. Socio-demographic features, body mass index, smoking status, concomitant diseases, income rates and BCG vaccination status of subjects were analyzed. RESULT: The study population comprised 123 adults with COVID-19 pneumonia [mean age = 49·7 years, standard deviation = 13·3 years; 82 (66·7%) male]. While the rate of cases vaccinated with BCG is lower (68·5 versus 88·2%, P = 0·026), mean age (54·0 ± 11·5 years versus 38·3 ± 10·7 years; P < 0·001), diabetes (32·6 versus 5·9%, P = 0·002) and low income (84·3 versus 52·9%, P < 0·001) are higher in patients with severe disease compared to those with mild disease. According to multivariate analysis increasing age [odds ratio (OR) = 1·119; 95% confidence interval (CI) = 1·062-1·178, P < 0·001] and low income (OR = 3·209; 95% CI = 1·008-10·222, P = 0·049) are associated with severe disease in COVID-19 pneumonia. CONCLUSION: This study reveals that BCG vaccination is not associated with disease severity in COVID-19 pneumonia. Age and low income are the main determinants of severe COVID-19 pneumonia.

Comparison of deformation by stereophotogrammetry of various kinds of major connectors in maxillary Kennedy Class I removable partial dentures.

PURPOSE: Major connectors must be rigid to perform their functions with maximum efficacy. This study investigated the deformation of four major connectors for maxillary Kennedy Class I removable partial dentures. MATERIALS AND METHODS: The designs were palatal plate, U-shaped plate, palatal strap, and anteroposterior bar. The deformation properties of major connectors were comparatively analyzed by two methods. In the photogrammetric part, a stereometric camera, Avipan-100 glass films, and an analytic apparatus were used. A computerized hydraulic machine was programmed to load the eight test dentures at 4-Hz frequency under a vertical load of 100 kg and a maximum of 300,000 cycles. The fluorescence penetrant liquid inspection test was used to detect the surface microcracks. RESULTS: The anteroposterior bar showed the least deformation. The other connectors, ranked in increasing order for the amount of deformation, were the U-shaped plate, the palatal strap, and the palatal plate. There were no microcracks in the U-shaped plate and the anteroposterior bar designs. CONCLUSION: Anteroposterior bar major connectors showed the least deformation among the maxillary major connector types tested. Microscopic cracks were seen in major connectors showing the highest degree of deformation and located at the depth of the hard palate.

Changes in mandibular ridge height in relation to aging and length of edentulism period.

This study investigated the mandibular height reduction in relationship to aging and the length of edentulism period. Data were collected from 120 edentulous male subjects (complete denture wearers) who were divided into two resorptive age groups. The edentulism period of the subjects was classified as 1 to 5, 5 to 10, and over 10 years. Ridge resorption was estimated on the panoramic radiograph by estimating the original height of the alveolar process as being three times the distance from the inferior border of the mandible to the inferior edge of the mental foramen. According to statistical analysis, the amount of mandibular height reduction increased in the older age group. The mandibular resorption rate was greatest in the earlier stages of edentulism and slowed with longevity of edentulism.