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D T Millett

Publications and source records attributed to D T Millett.

50 records · Page 3Linked to original sources
PubMed1999

A laboratory investigation to compare enamel preparation by sandblasting or acid etching prior to bracket bonding.

A laboratory investigation to compare the mean shear debonding force and mode of bond failure of metallic brackets bonded to sandblasted and acid-etched enamel is described. The buccal surfaces of 30 extracted human premolars were sandblasted for 5 seconds with 50 mu alumina and the buccal surfaces of a further 30 human premolars were etched with 37 per cent phosphoric acid for 15 seconds. Following storage for 24 hours at 37 degrees C in distilled water, shear debonding force was measured using an Instron Universal Testing Machine with a cross-head speed of 10 mm/minute. Mean shear debonding force was significantly lower for brackets bonded to sandblasted enamel compared to acid etched enamel (P < 0.001). Weibull analysis showed that at a given stress the probability of failure was significantly greater for brackets bonded to sandblasted enamel. Brackets bonded to etched enamel showed a mixed mode of bond failure whereas following sandblasting, failure was adhesive at the enamel/composite interface (P < 0.01).

Acid Etching, Dental↗
PubMed1998

Toward a perspective on orthodontic retention?

Retention is one of the most difficult challenges facing the clinician in orthodontics. In this article we collate current knowledge regarding the origin of orthodontic relapse and attempt to rationalize the necessary factors in planning orthodontic retention. Despite extensive research, the various elements leading to relapse of treated malocclusions are incompletely understood, giving rise to wide variation in retention protocols among clinicians. Informed consent-with emphasis on the features of the original malocclusion and the patient's growth pattern, the type of treatment performed, the need for adjunctive surgical procedures, the type of retainer, and the duration of retention-should be obtained during the planning of the retention phase. True perspective on orthodontic retention is lacking and there is a great need for further research to ensure that evidence-based clinical practice is adopted in retention strategies.

Adolescent↗
PubMed1998

Comparative laboratory investigation of dual-cured vs. conventional glass ionomer cements for band cementation.

This laboratory study compared the mean tensile bond strength, mode of band failure, and survival time of orthodontic bands cemented with dual-cured cement or conventional glass ionomer cement. Survival time was assessed following application of mechanical stress in a ball mill. Mean tensile bond strength was significantly higher for bands cemented with the dual-cured cement (p < 0.01), and mean survival time was significantly greater. Bands cemented with glass ionomer failed mainly at the cement/band interface. The results suggest that dual-cured cement is superior to glass ionomer for band cementation.

Chi-Square Distribution↗
PubMed1998

A 5-year clinical review of bond failure with a light-cured resin adhesive.

The purpose of this study was to investigate the time to first failure of stainless steel orthodontic brackets (Ormco Corp, Glendora, Calif) bonded with a light-cured resin adhesive (Transbond, 3M Unitek, Monrovia, Calif) and assess whether time to failure was related to the patient's age at the start of treatment or sex, the proficiency of the individual placing the brackets, or the presenting malocclusion. Data on 548 patients with 7118 bonded brackets were analyzed. Survival analysis was carried out on a single bracket per patient. In each patient, the first bracket to fail was studied. In cases where no brackets failed, the bracket with the shortest follow-up time was analyzed and handled as a censored observation in the formal analysis. Median time until first bracket failure was 442 days, and an overall failure rate of 6% was recorded. There were no significant differences in time to first failure of brackets with respect to the sex or age of the patient at the start of treatment (p = 0.168, and p = 0.261, respectively), operator proficiency in placing brackets (p = 0.189), or presenting malocclusion (p = 0.052). Performance of brackets bonded with Transbond does not appear to vary significantly according to the variables examined.

Adolescent↗
PubMed1996

Orthodontic bonding with glass ionomer cement--a review.

Orthodontic bonding with glass ionomer cement is comparatively new. The purpose of this article is to review the current literature covering both in vitro and in vivo studies of various glass ionomer cements that have been used for orthodontic bonding. The review indicates that there is little support in the literature to suggest that the currently available conventional glass ionomer cements are suitable for routine clinical use in orthodontics. Dual- or tri-cured hybrid materials, however, comprising both glass ionomer and resin components, appear to have greater potential with regard to clinical performance.

Dental Bonding↗
PubMed1995

The effect of sandblasting on the retention of first molar orthodontic bands cemented with glass ionomer cement.

This study examined the effect of sandblasting, in vitro, on the bond strength and survival time of first molar orthodontic bands. Survival time was assessed following simulated mechanical fatigue in a ball mill. The amount of cement left attached to the band after debanding was also assessed. In addition, the effect of sandblasting on the failure rate of 320 first molar bands cemented in 107 patients was examined in a half-mouth trial. Ketac-cem, mixed according to manufacturers' instructions was used as the luting agent for both laboratory and clinical trials. In vitro, sandblasting increased bond strength by 27 per cent (P < 0.01) and produced a three-fold increase in the median survival time relative to the untreated sample (P < 0.001) in the ball mill experiment. Sandblasting resulted in more cement remaining on the band rather than on the tooth enamel after band removal. In vivo, sandblasting reduced the clinical failure rate of the first molar bands (P < 0.001).

Adolescent↗
PubMed1994

A 5-year clinical review of bond failure with a no-mix adhesive (Right on).

The performance of 5941 stainless steel orthodontic brackets bonded with a no-mix adhesive (Right-on) in 563 patients was reviewed over a 5-year period. The effects of age and sex of the patient, treatment mechanics, operator experience, and arch location on the failure rate and mean survival time (MST) of bonded orthodontic brackets were examined. The overall failure rate was 8 per cent (MST 45.7 months). The failure rate of brackets was three times greater in patients aged less than 12 years at the start of treatment compared with those aged greater than 16 years at the start of treatment. The MST was significantly different between male and female patients. Brackets bonded in patients treated with Begg mechanics had a greater failure rate than those bonded in patients treated with other appliance mechanics. The failure rates and MST of brackets were significantly affected by all the variables examined.

Adolescent↗
PubMed1994

Orthodontic treatment in adults with periodontally involved labial segments.

During the last two decades notable advances have been made in the management of periodontal diseases. A better understanding of the basic biological principles of periodontal wound healing has provided a sound foundation for placing greater emphasis on conservative treatment regimes, including non-surgical treatments, less radical surgical techniques and the use of guided regenerative procedures to restore connective tissue attachment lost during disease progression. The consequence of these advances is that, even in cases of severely advanced periodontitis, careful planning and execution of treatment ensures that the disease does not continue to progress and the integrity of the dentition is maintained.

Adult↗
PubMed1992

The performance of first molar orthodontic bands cemented with glass ionomer cement--a retrospective analysis.

Various factors influencing the survival time of orthodontic bands cemented to first permanent molars with glass ionomer cement (KETAC-CEM, Espe) have been investigated. Data on 513 patients with 1424 first molar bands who completed orthodontic treatment between 1985 and 1989 inclusive were analysed. Performance of bands cemented to first permanent molars varied according to the operator, age of the patient and treatment mechanics, but not according to the sex of the patient or quadrant in which the band was fitted.

Adolescent↗
PubMed1988

Fracture of polycarbonate brackets--a related photoelastic stress analysis.

In clinical use polycarbonate edgewise bracket designs, patterned on metallic predecessors, have demonstrated slot-wing fracture. A preliminary two-dimensional photoelastic stress investigation is described in which two bracket designs, without angles in the edgewise slot component, are subjected to simulated palatal root torque mechanics.

Dental Stress Analysis↗
PubMedDate not supplied

The ball mill as a means of investigating the mechanical failure of dental materials.

OBJECTIVE: The main purpose of this paper is to present a new method of predicting clinical performance using mechanical loading in a ball mill. METHODS: A series of four experiments (two involving a hybrid composite and one each on orthodontic brackets and bands) is described in which the ball mill was used to subject specimens to mechanical fatigue. RESULTS: A reproducibility study using composite beam specimens showed no significant difference between the Mean Survival Time (MST) in all the three experimental runs (P = 0.42). When subjected to thermal cycling, the MST of the cycled group was 155.0 min compared to 247.0 min for the control group (P < 0.01). The MST of untreated and sandblasted brackets was 7.9 h and 14 h respectively (P < 0.01). There is also a significant difference (P < 0.001) in the MST of sandblasted bands when compared to the untreated bands. CONCLUSIONS: The ball mill proved to be a convenient and reproducible means of producing mechanical fatigue and may be useful in predicting the clinical performance of dental materials.

Bisphenol A-Glycidyl Methacrylate↗
PubMedDate not supplied

Fluoride release and cariostatic ability of a compomer and a resin-modified glass ionomer cement used for orthodontic bonding.

OBJECTIVES: The aims of this study were to compare the local and systemic uptake of fluoride released from a compomer material (Dyract Ortho) and a resin-modified glass ionomer cement (Vitremer) with that of a conventional resin adhesive (Right-On) and to compare the cariostatic ability of each of the test materials with that of the resin control. METHODS: Twenty six patients were randomly allocated to have a bracket bonded to a premolar on one side of the arch with one of the test materials and on the opposite side with the control material. Premolars destined for extraction as part of an orthodontic treatment plan were selected for bonding. A non-fluoride toothpaste was used by all participants for 4 weeks prior to bracket bonding and throughout the 4 week trial period. Fluoride release was measured in saliva, plaque and urine samples taken pre-bonding and 4 weeks post-bonding. Enamel demineralisation was assessed by scoring the buccal surface of each extracted tooth using a caries index. RESULTS: Neither Vitremer nor Dyract Ortho altered salivary or urinary fluoride concentration significantly 4 weeks post-bonding but plaque fluoride concentration increased significantly around premolars bonded with Vitremer. The test materials as a combined group were associated with significantly less demineralisation than the control material but there was no significant difference in cariostatic ability detected between either Dyract Ortho or Vitremer when each group was compared separately with the control. CONCLUSIONS: Fluoride released from Dyract Ortho or Vitremer is likely to exert a local and not a systemic effect. In a 4-week clinical study, the cariostatic ability of the fluoride-releasing cements, as a combined group, was superior to that of the non-fluoride releasing control but there was no significant difference in cariostatic ability between the two test materials when each test group was compared separately with the control.

Adolescent↗