Indications for caesarean sections at ≥34 weeks among nulliparous women and differential composite maternal and neonatal morbidity.

OBJECTIVE: To compare composite maternal and neonatal morbidities (CMM, CNM) among nulliparous women with primary indications for caesarean section (CS) as acute clinical emergency (group I; ACE), non-reassuring fetal heart rate (group II) and arrest disorder (group III). DESIGN: A multicentre prospective study. SETTING: Nineteen academic centres in the USA, with deliveries in 1999-2002. POPULATION: Nulliparous women (n = 9829) that had CS. METHODS: Nulliparous women undergoing CS for three categories of indications were compared using logistic regression model, adjusted for five variables. MAIN OUTCOME MEASURES: CMM was defined as the presence of any of the following: intrapartum or postpartum transfusion, uterine rupture, hysterectomy, cystotomy, ureteral or bowel injury or death; CNM was defined as the presence of any of the following: umbilical arterial pH <7.00, neonatal seizure, cardiac, hepatic, renal dysfunction, hypoxic ischaemic encephalopathy or neonatal death. RESULTS: The primary reasons for CS were ACE in 1% (group I, n = 114) non-reassuring FHR in 29% (group II; n = 2822) and failed induction/dystocia in the remaining 70% (group III; n = 6893). The overall risks of CMM and CNM were 2.5% (95% confidence intervals, CI, 2.2-2.8%) and 1.9% (95% CI 1.7-2.2), respectively. The risk of CMM was higher in group I than in group II (RR 4.1, 95% CI 3.1, 5.3), and group III (RR 3.2, 95% CI 2.7, 3.7). The risk of CNM was also higher in group I than in group II (RR 2.8, 95% CI 2.3, 3.4) and group III (RR 14.1, 95% CI 10.7, 18.7). CONCLUSIONS: Nulliparous women who have acute clinically emergent caesarean sections are at the highest risks of both composite maternal and neonatal morbidity and mortality.

The effect of eugenol-containing temporary cement on the bond strength of two resin composite core materials to dentin.

PURPOSE: This study investigated the effect of eugenol-containing temporary cement on the bond strength of two resin composite core materials (FluoroCore and Ti-Core) to dentin. MATERIALS AND METHODS: Dentin was exposed in three groups of extracted teeth (20 specimens each). In group one, dentin was covered with eugenol-containing temporary cement; the second group was covered with eugenol-free temporary cement; and the third group was left uncovered and served as a control group. All specimens were stored for 1 week at 37 degrees C and 100% humidity. The dentin surfaces were cleaned and treated using the GLUMA adhesive system, followed by placement of composite core build-ups. Debonding of the core material was accomplished using the Accuforce Elite test system. RESULTS: There was a significant reduction in bond strength for the specimens covered with eugenol temporary cement (p < .0001), but no significant difference was found between the control group and the group treated with eugenol-free temporary cement. Bond strength of the Ti-Core material to dentin was significantly higher than that of FluoroCore (p < .0001). CONCLUSION: Pretreatment of the dentin with eugenol-based temporary cement adversely affects the bond strength of resin composite core material to dentin.

Designs of bond strength tests for metal-ceramic complexes: review of the literature.

Despite the popularity of metal-ceramic restorations, the bonding mechanism remains the subject of theoretical discussion. Different experimental designs to evaluate bond strengths at the metal-ceramic interface are described. The effects of various stresses with each design are also discussed. A predictive experimental design should minimize variables and result in the least residual interfacial stresses. Dentists and dental technicians should benefit from comparisons of existing tests, and the discussion encourages introduction of more comprehensive approaches.

The effect of fluoride treatments on glazed and polished ceramic surfaces.

A scanning electron microscope (SEM) Study was conducted to evaluate the micromorphology of glazed and polished ceramic restoration surfaces after treatment with different types of fluorides with different concentrations and acidity. This study showed that glazed ceramic surfaces appeared to be smoother and more resistant to fluoride agents than polished ceramic surfaces. Fluoride agents with a lower pH (more acidic) and higher in fluoride concentration caused more surface damage to porcelain. Therefore, it is recommended to use a neutral fluoride agent with low fluoride concentration. If the ceramic restoration is to be polished after glazing due to clinical adjustment, it is advisable to reglaze it particularly before fluoride application.

A qualitative study for the bond and color of ceramometals. Part II.

Many dentists, porcelain manufacturers, and dental technicians empirically state that repeated firings tend to bleach out or alter the original shade of porcelain. This investigation used a sophisticated colorimeter to resolve the controversy. The effect of temperature rise and number of firings had varying effects on color relative to brand of porcelain and specific alloy.

A qualitative study for the bond and color of ceramometals. Part I.

A shear testing method was devised to study and evaluate the effect of various and repeated firing cycles, types of alloy, and brand of porcelain relative to the color and bond strength of ceramometal complexes specifically at the opaque porcelain-metal interface and the opaque-body porcelain juncture. Two alloys and two porcelain brands were chosen on the basis of their widespread clinical use and the marked contrast between them. An increase of the firing temperature significantly raised the bond strength for all alloy-porcelain combinations.

A shear test for the bond strength of ceramometals.

An innovative shear-testing method was introduced to study the effect of firing temperature, type of metal, and surface texture on the bond strength of the ceramometals. Two common ceramic/metal alloys were used: Olympia, a precious alloy, and Talladium, a base alloy. A Ceramco II Paint-O-Pake opaque was selected for the study. Each porcelain alloy was prepared in a similar manner before porcelain application to achieve uniform surfaces. A separate category of base alloy samples was subjected to etching after sandblasting. Each category was then divided into two groups. Opaque porcelain was fired according to the manufacturer's instructions in one group and 65 degrees F higher in the other. The bond strengths were compared by statistical analysis and post-tested samples were evaluated visually and microscopically with a scanning electron microscope.