Colagem de "brackets" ortodônticos metálicos com dyract em esmalte bovino: resistência ao cisalhamento em funçäo do uso ou näo de condicionamento ácido e de "primer" / The metallic orthodontic bracket bonding with Dyract in bovine enamel the shear bond strength with or without acid conditioning \"Primer\"

O objetivo deste trabalho foi avaliar a resistência ao cisalhamento da colagem de brackets ortodônticos metálicos com o compômero Dyract (De Trey - Dentsply) em esmalte bovino, com condicionamento ácido seguido ou näo de Primer PSA (respectivamente os grupos A e B), ou sem condicionamento ácido seguido ou näo de Primer PSA (respectivamente os grupos C e D). Nas quatro situaçöes (grupos A, B, C e D), os brackets foram colados de acordo com a maneira convencional. Os resultados relativos à resistência ao cisalhamento em kgf/cm2 foram: grupo A, 108,24; grupo B, 78,04; grupo C, 98,51; e grupo D, 21,93. Conclusäo: houve diferença estatística entre os grupos; exceto entre os grupos A e C

Dental composite for the fixation of mandibular fractures and luxations in 11 cats and 6 dogs.

Twenty-one mandibular fractures in 11 cats and 6 dogs were repaired during a 20-month period. A new technique using dental composite was used to stabilize the mandible. The canine teeth were pumiced, acid etched, and aligned with dental composite, leaving the mouth opened approximately 1 cm. Six weeks after surgery the composite was removed so that radiographs of the mandible could be made with the animal under general anesthesia. In 1 dog in which the fracture had not healed, the composite was replaced. The composite broke before 6 weeks in 8 animals; 2 required replacement of the dental composite. There were no other complications. The median time for fracture healing was 6 weeks. All fractures healed with anatomic dental occlusion. The advantages of this technique are that no further damage is caused to the teeth or to the blood supply of the bone, the occlusion is anatomic, dermatitis (which is seen with tape muzzles) is not a complication, and the technique is easy to use in brachycephalic breeds, cats, and animals with poor bone quality. The limiting factor of this technique is that it does require four salvageable canine teeth. This repair technique is still a viable option even if one or more of the canine teeth are fractured. Dental composite stabilization is fast, easy, inexpensive, and, in our series, it was 100% effective for the repair of mandibular fractures.

Organic structures of the hypercalcified peritubular matrix in horse dentine.

EDTA-insoluble organic structures of the hypercalcified peritubular matrix (PM) in horse dentine were observed by scanning electron microscopy. The PM was enveloped in double cylindrical structures composed of fibrillar sheaths in the inner and outer peripheries. Between the outer fibrillar sheath and intrinsic fibrils of the intertubular matrix, a calcified cementing membrane existed. Within the PM, warped cone-shaped structures of fibrillar sheaths, overlapping at intervals of 4-6 microns and semiconcentrically surrounding the dentinal tubule, extended from the inner fibrillar towards the outer fibrillar sheath. The cone-shaped fibrillar sheaths following the inner and outer fibrillar sheaths were identified as the incremental lines of the PM. Most of these fibrils may be collagen although it could not be confirmed, whereas non-collagenous organic materials in the lateral branches of the dentinal tubule are radially arranged in the PM. These EDTA-insoluble structures were three-dimensionally illustrated using an image-analysing system.