The effect of a mandibular advancement splint in subjects with sleep-related breathing disorders.

OBJECTIVE: This study assessed the effectiveness of a mandibular advancement splint (MAS) in subjects with sleep-related breathing disorders using both objective and subjective outcome measures. DESIGN: The study was carried out as a retrospective analysis. SETTING: The study was conducted within the Sleep Studies Unit at the Queen Victoria Hospital, East Grinstead, between May 1997 and March 2000. SUBJECTS AND METHODS: Twenty subjects with obstructive sleep apnoea (OSA) and six with non-apnoeic snoring, diagnosed by overnight polysomnography, were fitted with a monobloc appliance between May 1997 and March 2000. MAIN OUTCOME MEASURES: The subjects were analysed for changes in the respiratory disturbance index (RDI) and Epworth Sleepiness Scale (ESS) scores. In addition each subject completed an outcome questionnaire following fitting of the appliance. RESULTS: Variability in response measured by the change in the respiratory disturbance index was found with no correlation to the baseline recording. Although median RDI values improved in both groups, significantly so in the obstructive sleep apnoea group (p<0.05), seven subjects exhibited an increased RDI score following mandibular advancement splint therapy. The median Epworth Sleepiness Scale scores decreased in both the OSA group and the non-apnoeic snorers although not significantly. Twenty-one of the 26 subjects completed the outcome questionnaire revealing an 81% reduction in snoring. Side-effects were generally transient and minor. Eighty-six per cent of the subjects' partners reported better quality of sleep as a result of MAS therapy. CONCLUSIONS: The monobloc appliance significantly improved the Respiratory Disturbance Index in the obstructive sleep apnoea group. Some subjects had increased RDI scores following splint therapy. This supports the need for an objective assessment in the follow-up of patients treated with mandibular advancement splints.

Aesthetic brackets: to perfect or to reject?

Orthodontists are now treating patients who are demanding high quality orthodontics which is also aesthetically pleasing. The quest for an aesthetic yet strong appliance has led to many innovative designs. This article summarizes the main advances.

Bond strengths of five different ceramic brackets: an in vitro study.

The purpose of this investigation was to compare the bond strengths to enamel obtained in shear/peel and tensile/peel modes of testing using five different ceramic brackets and two different light-cured composites. The site of failure was also examined. Shear/peel bond strength was significantly affected by adhesive type, with Heliosit having higher mean bond strengths than Prismafil. Bond strength was significantly affected by bracket type; the highest mean bond strength in both tests being attained using Transcend with Heliosit. All brackets resisted shear/peel forces better than tensile/peel forces. High bond strengths are associated with an increased incidence of bracket and enamel fractures with Transcend and Starfire.

A comparison between the old Transcend and the new Transcend series 2000 bracket.

The shear/peel and tensile/peel bond strengths of the original Transcend and the new Transcend series 2000 bracket were determined using two different light-cured composites, Prismafil (high filler) and Heliosit (low filler). Predominant sites of failure were recorded for each bracket with each cement in each mode of testing. Transcend series 2000 produced higher bond strengths than Transcend in shear/peel, but were significantly weaker in tensile/peel testing. Heliosit generally produced higher bond strengths than Prismafil. Enamel fractures were observed with Transcend in both modes of testing when bonded with Heliosit, but not with Transcend series 2000 when bonded with Heliosit. The new Transcend series 2000 brackets should only be removed in tensile/peel mode as suggested by the manufacturers, due to their very high bond strengths in shear.

An evaluation of zirconium oxide brackets: a preliminary laboratory and clinical report.

A pre-production sample of zirconium oxide (ceramic) brackets was examined in this study. A laboratory investigation of the tensile/peel bond strength of the brackets was carried out using two light-cured adhesives (Prismafil and Heliosit) and one chemically-cured adhesive (Delphic). The mode of failure was also investigated using optical and scanning electron microscopy. The bond strengths achieved with Prismafil were statistically significantly (P less than 0.05) lower than Heliosit and Delphic between which no significant differences were found. All samples failed at the bracket-adhesive interface. A clinical test demonstrated the extreme ease of sliding along stainless steel and nickel-titanium archwires, and revealed a low plaque adhesion. The principal disadvantage of these brackets appears to be their off-white highly opaque appearance which in addition to giving poor aesthetics may adversely affect bond strength with light-cured adhesives.

A clinical comparison of the quadhelix appliance and the nickel titanium (tandem loop) palatal expander: a preliminary, prospective investigation.

Maxillary expansion using either a quadhelix appliance (Qx) or a nickel titanium palatal expander (Nt) was prospectively compared in 28 consecutive new patients (19 female, nine male) presenting with posterior buccal segment crossbites. Study models taken at each activation were measured to determine the mean maxillary expansion efficacy (Emax) and the mean expansion rate (m(max)) across the first molars and first premolars. Patient discomfort was assessed using visual analogue scores, and cost-effectiveness was also considered. Neither Emax nor m(max) differed significantly between Qx and Nt across either the first molars or the first premolars. However, both Emax and m(max) were significantly greater across the first molars than across the first premolars only with Qx (Emax: 8.4 +/- 0.7 mm versus 5.1 +/- 0.6 mm, P = 0.001; m(max): 0.09 +/- 0.005 mm/day versus 0.05 +/- 0.006 mm/day, P = 0.0001). In addition, greater variance was apparent in m(max) with Nt than with Qx across both the first molars and the first premolars. Overall, Qx and Nt elicited similar discomfort. However, significantly less was reported with Nt on days 6 (P = 0.04) and 7 (P= 0.03) following the second 'activation'. These preliminary results suggest that Qx and Nt are equally efficacious maxillary expanders. However, Qx expansion appeared significantly more controlled, as well as more individually predictable in expansion rate. Overall, Qx and Nt probably elicit similar discomfort, but significantly less discomfort may be seen with Nt following the second activation. Finally, because more than one appliance is invariably required with Nt, Qx expansion is potentially less costly.