Psychiatric disorders in a dental clinic

This paper describes the psychiatric disorders seen in 138 consecutive attenders at a psychiatric clinic in a dental hospital. The disorders were rated using a standardised interview, and assigned a diagnosis in accordance with a multiaxial classification known as the DSM-III. The rate of psychiatric disorder seen in these patients was over 90% and the implications of this are discussed.     

Clinical measurement of palatal tooth wear following coating by a resin sealing system

This study investigated the hypothesis that coating eroded teeth with a resin-based dentin bonding agent gave protection from tooth wear. Nineteen adults with palatal tooth wear exposing dentin were recruited, following referral by their general dental practitioner. Alternate teeth were coated with the resin adhesive, while the uncoated teeth acted as controls. Accurate impressions of the eroded teeth, onto which were cemented machined stainless steel discs to act as reference areas, were scanned with a non-contacting laser profilometer at 3, 6, 12 and 24 months. The mean thickness of resin at baseline application was 0.15 mm and, from 0 to 6 months, the rate of wear of the control teeth was higher than those covered with Seal & Protect. There was a statistically significant difference in "wear" measured between resin covered and control teeth at three months. The Inter Class Correlations (repeated measurements) for the step heights obtained for the original and repeat impressions was excellent at 0.99. This study shows that coating eroded teeth with a resin-based adhesive has the potential to prevent further tooth wear.     

Ostene, a new water-soluble bone hemostasis agent

Traditional formulations of bone wax are composed largely of beeswax and are well known to interfere with bone healing and cause inflammatory reactions. Ostene, a newly available bone hemostasis agent made of water-soluble alkylene oxide copolymers, was evaluated. The soft tissue response to Ostene was compared with bone wax and a polyethylene control after implantation into the paravertebral muscles of three rabbits. After 2 weeks, Ostene elicited no fibrous response, the polyethylene elicited a thin (less than 0.5 mm) fibrous response, and the bone wax was encased in a fibrous capsule 0.6 to 1.0 mm thick infiltrated with inflammatory cells. The effects of Ostene were compared with bone wax in a femur defect model in eight rabbits. Ostene showed no evidence of an adverse response in the cortical defect site, medullary cavity, or the surrounding tissue at 4 and 8 weeks. In contrast, bone wax at both time intervals elicited a foreign body response consisting of fibrous tissue infiltrated by macrophages, giant cells, and lymphocytes at the sites of the bone defects. Bone wax also displaced the bone marrow and interfered with bone ingrowth into the defects. Ostene provides the clinician a water-soluble bone hemostasis material that does not demonstrate the adverse tissue response or the interference with bone healing seen with the use of bone wax.     

EDTA or H3PO4/NaOCl dentine treatments may increase hybrid layers’ resistance to degradation: A microtensile bond strength and confocal-micropermeability study

Objectives

The aim of this study was to reduce hybrid layer degradation created with simplified dentine adhesives by using two different methods to condition the dentine surface.

Methods

A smear-layer was created on flat dentine surfaces from extracted human third molars with a 180-grit/SiC-paper. Dentine specimens were conditioned before bonding with the following procedures: 37% H₃PO₄; H₃PO₄/0.5% NaOCl; 0.1 M EDTA; 0.1 M EDTA/0.5% NaOCl. Two etch-and-rinse adhesives: (Scotchbond 1XT or Optibond Solo Plus) were applied and light-cured. Composite build-ups were constructed. The bonded teeth were sectioned into beams, stored in distilled water (24 h) or 12% NaOCl solution (90 min) and finally tested for microtensile bond strengths (μTBS). Additional dentine surfaces were conditioned and bonded as previously described. They were prepared for a pulpal-micropermeability confocal microscopy study and finally observed using confocal microscopy.

Results

μTBS results revealed that both adhesives gave high bond strengths to acid-etched dentine before, but not after a 12% NaOCl challenge. Bonds made to acid-etched or EDTA-treated dentine plus dilute NaOCl, gave high μTBS that resisted 12% NaOCl treatment, as did EDTA-treated dentine alone. A confocal micropermeability investigation showed very high micropermeability within interfaces of the H₃PO₄, etched specimens. The lowest micropermeability was observed in H₃PO₄ + 0.5% NaOCl and 0.1 M EDTA groups.

Conclusions

The use of dilute NaOCl (0.5%) after acid-etching, or the conditioning of dentine smear layers with 0.1 M EDTA (pH 7.4) produced less porous resin–dentine interfaces. These dentine-conditioning procedures improve the resistance of the resin–dentine bond sites to chemical degradation (12% NaOCl) and may result in more durable resin–dentine bonds.     

The effect of clenching on condylar position: A vector analysis model

STATEMENT OF THE PROBLEM: Clinicians often disagree about the acceptable position of the condyle in the articular fossa. Agreement as to what position the condyle-disk assembly assumes on the articular eminence while subjected to the forces of the elevator muscles of the mandible is important. PURPOSE: This simulation study investigated the position of the condyle-disk assembly on the articular eminence while subjected to the forces of the elevator muscles of the mandible during clenching. MATERIAL AND METHODS: Using the 2 conditions of static equilibrium, a vector analysis of a 2-dimensional model of the temporomandibular joint was developed. The dynamics of the condyle-disk assembly during muscle loading were analyzed. The vector sum of the masticatory muscle forces was determined by assuming that the maximum force developed by each contributing muscle was proportional with the physiologic cross section of the muscle. The effect of the resultant force vector of the combined muscle action applied to the condyle was analyzed for the orthogonal and acute angle situations. RESULTS: When the vector sum was orthogonal on the eminence, the condyle was in stable equilibrium. The stable equilibrium was found in the anterior-superior position in the fossa. When the vector sum was at an acute angle to the eminence, the condyle was subject to a translation force that displaced it into the anterior-superior equilibrium position. CONCLUSION: Within the limitation of this study, vector analysis suggested that the anterior-superior position of the condyle-disk assembly on the eminence was the most stable equilibrium position. All other tested positions of the condyle were less stable and maintained at the expense of other structures.     

The hyoid bone in malay infants with cleft lip and palate.

OBJECTIVE: To compare morphological and positional variations of the hyoid bone in unoperated infants with cleft lip and palate (CL/P) with those in noncleft infants. DESIGN: Retrospective, cross sectional. PATIENTS AND METHODS: Three-dimensional computed tomography scans were obtained from 29 unoperated CL/P infants of Malay origin aged between 0 and 12 months and from 12 noncleft infants in the same age range. Observations were made and measurements were obtained with a software package developed at the Australian Craniofacial Unit. The sizes of the hyoid bones and the position of the hyoid body and epiglottis in relation to the cervical spine were measured. Anatomical anomalies of the hyoid and prevalence of aspiration pneumonia were also documented. RESULTS: The hyoid bones and epiglottis were found to be located more inferiorly in CL/P infants compared with the noncleft infants. Also, 17% (5/29) of the CL/P infants had nonossified hyoid bodies. CONCLUSION: The results suggest that there are differences in the location and genesis of the hyoid bone in infants with CL/P that warrant further investigation.