The effect of core:dentin thickness ratio on the bi-axial flexure strength and fracture mode and origin of bilayered dental ceramic composites.

OBJECTIVES: The aim of the current study was to assess the effect of core:dentin thickness ratio on the flexure strength, fracture mode and origin of bilayered dental ceramic composite disc specimens. METHODS: Sets of 30 bilayered composite discs with core:dentin thickness ratio of 2:1, 1:1 and 1:2 were tested in bi-axial flexure with both the reinforcing core and veneering dentin loaded in tension. Mean flexure strengths, standard deviations and associated Weibull Moduli (m) were determined. A combination of optical and scanning electron microscopy was employed for identification of the fracture mode and origin. RESULTS: The core:dentin ratio influenced the bi-axial flexure strength and reliability of the flexure strength data when both the reinforcing core and veneering dentin porcelain were tested in tension. The strength and reliability was increased for a core:dentin thickness of 2:1. The number of fracture fragments, the frequency of occurrence of specimen delaminations, Hertzian cone formations and sub-critical radial cracking in the bilayered dental ceramic composite disc shaped specimens was also dependent on the core/dentin ratio and the surface loaded in tension. CONCLUSIONS: Core:dentin thickness ratio influences the bi-axial flexure strength and fracture mode and origin in bilayered dental ceramic composite specimens.     

Factors influencing defects of rotary nickel-titanium endodontic instruments after clinical use

This study examined used, discarded rotary nickel-titanium instruments obtained from 14 endodontists in four countries, and identified factors that may influence defects produced during clinical use. A total of 7,159 instruments were examined for the presence of defects. Unwinding occurred in 12% of instruments and fractures in 5% (1.5% torsional, 3.5% flexural). The defect rates varied significantly among endodontists. Instrument design factors also influenced defect rate, but to a lesser extent. The mean number of uses of instruments with and without defects was 3.3 +/- 1.8 (range: 1-10), and 4.5 +/- 2.0 (range: 1-16), respectively. The most important influence on defect rates was the operator, which may be related to clinical skill or a conscious decision to use instruments a specified number of times or until defects were evident.     

Severe proliferative congenital temporomandibular joint ankylosis: a proposed treatment protocol utilizing distraction osteogenesis

The classical treatment for temporomandibular joint (TMJ) ankylosis in children: 1) joint release; 2) arthroplasty; 3) reconstruction; and 4) postoperative physical therapy (PT), is often unsuccessful. Postoperative physical therapy is difficult in the young patient due to poor cooperation. Moreover, there is a subgroup of patients who have a refractory congenital proliferative bony process that is the cause of their disease. In these patients, a role for distraction osteogenesis (DO) has been defined. We present a series of young patients with congenital proliferative TMJ ankylosis. Some have failed classic treatment. In such cases, DO is used to expand the mandibular size and soft tissue matrix. This creates a static open bite, facilitates mid-facial growth, and avoids compromise of the airway, speech, nutrition, and oral hygiene. To maintain these objectives, mandibular DO may be repeated as the child matures. Once skeletal maturity is reached, DO is used to normalize occlusion and further expand the soft tissue envelope prior to definitive reconstruction and aggressive post-op PT. In seven patients, this protocol has been used. Five patients are currently in the active phase of growth and undergoing interim treatment with mandibular DO. Two patients have reached skeletal maturity and have completed the protocol of DO with definitive arthroplasty and reconstruction. DO is a valuable aid in the treatment of the problematic child with congenital proliferative TMJ ankylosis. Interim DO, prior to definitive arthroplasty and reconstruction, can provide a static open bite that prevents progressive deformity and its associated functional disturbances.     

Screening for cardiovascular risk factors in a dental setting

BACKGROUND: The authors assessed the utilization of oral health care professionals (OHCPs) as a resource for identifying patients who were unaware of their increased risk of developing cardiovascular disease (CVD). METHODS: OHCPs administered a CVD risk-screening questionnaire, measured blood pressure and tested cholesterol levels, high-density lipoprotein levels and hemoglobin A1c (HgA1c) levels using "finger-stick" blood testing in 100 patients treated in a dental school clinic who were unaware of their CVD risk status. The authors determined the prevalence of specific risk factors (that is, smoking and abnormal levels of systolic blood pressure, lipids, body mass index and HgA1c) and calculated Framingham 10-year coronary heart disease (CHD) risk scores. RESULTS: Seventeen percent of the 100 patients (35 percent of men, 5 percent of women) had an increased global risk of experiencing a CHD event within 10 years (Framingham risk score>10 percent). Seventy-three percent of participants had one or more risk factors and 31 percent had two or more risk factors present. More men than women had low levels of high-density lipoprotein (45 percent [18/40] of men versus 3.3 percent [2/60] of women; P<.0001). The mean Framingham CHD risk score increased with increasing risk factor burden. CONCLUSIONS: OHCPs identified patients with an increased CHD risk who could benefit from primary prevention activities. A substantial proportion of study patients who were unaware of their risk status were at an increased risk of experiencing a CHD event within 10 years. OHCPs could contribute to public health CHD control efforts.     

Australian Dental Research Fund Trebitsch Scholarship* Efficacy of antifungal prophylaxis in bone marrow transplantation

Oral candidal infection is a common problem in bone marrow transplantation. This prospective study compared the effectiveness of antifungal prophylaxis with topical antifungals (nystatin and amphotericin B suspensions) versus oral fluconazole in 196 patients undergoing bone marrow transplantation. Oral candidosis occurred frequently in the group receiving topical antifungals (61/113, 54%), but was rare in the group receiving fluconazole (6/83, 7%). The difference in efficacy between the two groups was highly significant (p<0.00001). There was no difference in the incidence of suspected systemic fungal infection between the two groups. While nausea was a problem with antifungal suspensions, no significant adverse reactions to fluconazole occurred. Because of greater efficacy in preventing oral candidosis and better patient tolerance, oral fluconazole is preferred to antifungal suspensions for prophylactic use in patients undergoing bone marrow transplantation.     

Effective recruitment and retention strategies for underrepresented minority students: perspectives from dental students

This study was designed to identify reasons underrepresented minority (URM) dental students select a dental school and to determine the factors that contribute to their resolve to complete their programs. A survey questionnaire developed from interviews with URM students was sent to Minority/Admissions Officers or deans of dental schools that enrolled URM students for distribution to their minority students. A total of 198 questionnaires were received from minority students in all levels of dental school. The results were that 74 percent said they selected a school for its reputation, and 49.5 percent chose a dental school even if the financial aid package was less than what was offered in other schools. African American, Hispanic, and Native American students prefer integrated interview days with nonminority applicants and disapprove of "special" days designated for URMs. The presence of other minority students was not an important factor in the selection of a school but is an important source of support while attending dental school. Dental school minority alumni also play a significant role in the selection of a school. Results of the study can be useful in planning recruitment and retention programs.     

Short-Term Results of IPS-Empress Inlays and Onlays

Purpose A leucite-reinforced, glass-ceramic material was recently introduced for clinical use. In this clinical trial, IPS-Empress inlays and onlays were evaluated using the modified United States Public Health Service (USPHS) criteria. Materials and Methods The teeth of 36 patients were restored with 105 posterior inlays and 25 onlays, fabricated by an indirect technique. After etching the restorations with hydrofluoric acid, they were silanized and luted using composite cements. The restorations were evaluated visually, clinically with a mirror and probe, and by bitewing radiographs and clinical photographs, using modified USPHS criteria. Restorations having neither charlie nor delta criteria were defined as successful, and their survival rate was calculated according to Kaplan-Meier analysis. Results The mean observation period for the 130 restorations was 23.4 ± 6.1 months. After 2 years, 127 restorations were successful with an estimated survival rate of 97.5%. Three restorations failed because of fractures. The esthetic results were excellent. Conclusions The initial clinical results of this esthetic restorative material are encouraging. However, because of fatigue phenomena for all ceramic materials, a longer observation period is needed to provide a definitive prognosis of the long-term clinical behavior.     

HIV infection and the dentist. 2. The diagnosis and management of gingivitis and periodontitis

In HIV infected patients, a distinct form of gingivitis and periodontitis was reported recently. This paper reviews the clinical and microbiological features of these lesions and makes recommendations regarding their clinical management. The need for early treatment and control of periodontitis in HIV seropositive patients is emphasized.