Simplified method for determining fracture toughness of two dental ceramics.

This study compared the fracture toughness values (KIC), which were derived from simplified techniques: the indentation fracture (IF), the indentation strength (IS), and fractographic approach to that from a standard testing using surface cracks in flexure (SCF). Forty bar specimens, twenty IPS Empress(®) Esthetic and twenty IPS e.max(®)Ceram were prepared. Ten specimens in each material were tested by IF technique, IS technique and fractographic approach, and additional 10 specimens were tested by the SCF technique. This study showed that the mean KIC derived from fractographic approach were not significantly different from that of the SCF in both materials (p>0.05) whereas the mean KIC from indentation techniques rarely agreed with those of the standard technique. The KIC determination is sensitive to the methods used that affect accuracy. Consequently, test selection should be based on a sound understanding and inherent limitations of each technique.

Sectional collapsible complete removable dental prosthesis for a patient with microstomia.

Patients who have unusually small mouths may have difficulty in obtaining dental care and maintaining good oral hygiene. The fabrication of conventional complete removable dental prostheses for an edentulous patient with microstomia is challenging because of the limited access to the oral cavity. Sectional collapsible complete removable dental prostheses were designed as hinged maxillary and mandibular complete dentures that can be folded for denture delivery. This design also prevented denture deflection during function by using the upper part of the prosthesis, minimizing the possibility of breakage.

The relationship of maxillary canines to the facial anatomical landmarks in a group of Thai people.

PURPOSE: The objective was to evaluate canine positions, intercanine tip width (ICTW) and width of distal surface of canine (WDC), related to facial landmarks including interalar width (IAW), intercommissural width (ICoW), and distance between left and right projection lines drawn from inner canthus of eyes to alae of the nose (DPICa) in a group of Thai. MATERIALS AND METHODS: One hundred Thai subjects aged 18-35 years were selected. IAW and ICoW were measured on subject's face using digital vernier caliper. Irreversible hydrocolloid impression of the upper arch was taken, and a cast was poured with dental stone. Silicone impression material was used to take imprint of the incisal edge of upper six anterior teeth. DPICa was obtained from the subject's face using custom-made measuring equipment and marked on the silicone incisal imprint. The marks were then transferred from the imprint to the stone cast and measured with digital caliper. The ICTW and WDC were also measured on the stone cast. Pearson's correlation was used to determine the correlation. RESULTS: The results revealed that the correlation between ICTW-ICoW was 0.429 and ICTW-DPICa was 0.573. The correlation between WDC-ICoW was 0.426 and WDC-DPICa was 0.547. However, IAW did not show any correlation with ICTW or WDC (P>.05). CONCLUSION: The correlation between canine position and facial landmarks was found. ICTW and WDC had relationship with ICoW and DPICa. DPICa showed stronger correlation with the position of maxillary canine than that of ICoW.