D. T. Millett

Current Products and Practices: Applications of 3D imaging in orthodontics: Part II

Part I of this paper describes the background, general concepts, available techniques and the clinical applications of recording external craniofacial morphology in three dimensions. Part II explores the different 3D techniques of imaging the dental arches, and their possible uses in orthodontic diagnosis and treatment.Part I of this paper describes the background, general concepts, available techniques and the clinical applications of recording external craniofacial morphology in three dimensions. Part II explores the different 3D techniques of imaging the dental arches, and their possible uses in orthodontic diagnosis and treatment.Part I of this paper describes the background, general concepts, available techniques and the clinical applications of recording external craniofacial morphology in three dimensions. Part II explores the different 3D techniques of imaging the dental arches, and their possible uses in orthodontic diagnosis and treatment.

Fluorides, orthodontics and demineralization: a systematic review

Objectives To evaluate the effectiveness of fluoride in preventing white spot lesion (WSL) demineralization during orthodontic treatment and compare all modes of fluoride delivery. Data sources The search strategy for the review was carried out according to the standard Cochrane systematic review methodology. The following databases were searched for RCTs or CCTs: Cochrane Clinical Trials Register, Cochrane Oral Health Group Specialized Trials Register, MEDLINE and EMBASE. Inclusion and exclusion criteria were applied when considering studies to be included. Authors of trials were contacted for further data. Data selection The primary outcome of the review was the presence or absence of WSL by patient at the end of treatment. Secondary outcomes included any quantitative assessment of enamel mineral loss or lesion depth. Data extraction Six reviewers independently, in duplicate, extracted data, including an assessment of the methodological quality of each trial. Data synthesis Fifteen trials provided data for this review, although none fulfilled all the methodological quality assessment criteria. One study found that a daily NaF mouthrinse reduced the severity of demineralization surrounding an orthodontic appliance (lesion depth difference −70.0 μm; 95% CI −118.2 to −21.8 μm). One study found that use of a glass ionomer cement (GIC) for bracket bonding reduced the prevalence of WSL (Peto OR 0.35; 95% CI 0.15–0.84) compared with a composite resin. None of the studies fulfilled all of the methodological quality assessment criteria. Conclusions There is some evidence that the use of a daily NaF mouthrinse or a GIC for bonding brackets might reduce the occurrence and severity of WSL during orthodontic treatment. More high quality, clinical research is required into the different modes of delivering fluoride to the orthodontic patient.

Methods of assessment of cleft-related facial deformity: A review

Objective To review the stimulus media, measurements and scoring system, raters characteristics, and facial region used in assessment of the appearance of cleft-related deformity. Methods A review of the literature was conducted using MedLine from January 1966 to June 2003. Key orthodontic journals and The Cleft Palate–Craniofacial Journal were hand searched as well. Results Most studies used a static two-dimensional means of assessment. Direct clinical assessment, three-dimensional media, or both have been used to a lesser extent. Only one study utilized all three assessment media. Three studies, however, attempted to compare the direct clinical assessment with that obtained using two-dimensional media. Most of the studies demonstrated that appearance of the cleft-related deformity could be measured by a variety of judges. The reliability and validity of the three different media as methods of assessment have received limited attention. The facial area assessed has varied from the full face, nasolabial area, or specific features of the lip or nose. Conclusions Wide variation exists in the study design related to assessment of cleft-related deformity. An internationally agreed objective method of assessment for this facial deformity is required. A three-dimensional, rather than a two-dimensional, means of assessment should be adopted.

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 patients 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.

Current Products and Practices

Part I of this paper describes the background, general concepts, available techniques and the clinical applications of recording external craniofacial morphology in three dimensions. Part II explores the different 3D techniques of imaging the dental arches, and their possible uses in orthodontic diagnosis and treatment.Part I of this paper describes the background, general concepts, available techniques and the clinical applications of recording external craniofacial morphology in three dimensions. Part II explores the different 3D techniques of imaging the dental arches, and their possible uses in orthodontic diagnosis and treatment.Part I of this paper describes the background, general concepts, available techniques and the clinical applications of recording external craniofacial morphology in three dimensions. Part II explores the different 3D techniques of imaging the dental arches, and their possible uses in orthodontic diagnosis and treatment.

The effect of saliva on enamel and dentine erosion

The present study aims to assess the ability of saliva, both in vitro and in situ, to prevent surface mineral loss from enamel and dentine when exposed to an erosive challenge. Fifteen groups of four varnished thin tooth sections were stored in saliva collected from individuals taking part in the in situ study and a further eight groups, each containing four sections, were stored in deionised water. In vitro, sections were stored in saliva or water for 14 days. In addition, fifteen subjects each wore an appliance with four varnished sections. Appliances with sections were worn for 14 days. All sections were exposed to 25 ml of erosion solution for 5 min twice daily. Microradiography and image analysis of the recovered sections demonstrated significant protection of surface mineral loss from enamel and dentine by saliva in vitro and in situ compared with deionised water (p < 0.05). Significantly less mineral loss (p < 0.05) was observed for enamel and dentine stored in situ compared with storage in saliva in vitro. Generalised linear modelling demonstrated both the subject and protocol had significant effect on mineral loss. A weak positive correlation (r = 0.64) was noted when in situ and in vitro mineral loss from enamel were compared, demonstrating greater reactivity of the in vitro enamel specimens to the erosion challenge. The dentine data did not show any linear correlation. Saliva protected against mineral loss by erosion and, for enamel, in vitro results demonstrated a weak positive correlation with in situ results.

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.

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.

Orthodontic retention: A systematic review

Objective To evaluate the effectiveness of different retention strategies used to maintain tooth position after treatment by orthodontic appliances. Data sources The search strategy was carried out according to the standard Cochrane systematic review methodology. The following databases were searched for randomized clinical trials (RCT) or controlled clinical trials (CCT): Cochrane Oral Health Group Trials Register, Cochrane Clinical Trials Register, MEDLINE and EMBASE. No language restrictions were applied. Authors of trials were contacted to identify unpublished trials. Inclusion and exclusion criteria were applied when considering the studies to be included and a quality assessment made for each paper. Data selection The primary outcome was the amount of relapse. Secondary outcomes were survival of retainers, adverse effects on oral health and patient satisfaction. Data extraction Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two reviewers. Five studies (2 RCTs and 3 CCTs) fulfilled the inclusion criteria. Data synthesis There was evidence, based on data from one trial, that there was a statistically significant increase in stability in both the mandibular (P<0.001) and maxillary anterior segments (P<0.001) when the CSF (circumferential supracrestal fiberotomy) was used in conjunction with a Hawley retainer, compared with a Hawley retainer alone. However, this evidence may be unreliable due to flaws in the study design. There was also weak, unreliable evidence that teeth settle quicker with a Hawley retainer than with a clear overlay retainer after 3 months. Conclusions There is currently insufficient evidence on which to base the clinical practice of orthodontic retention.

The Role of Sandblasting on the Retention of Metallic Brackets Applied with Glass Ionomer Cement

A laboratory investigation of the shear and strength of stainless steel brackets applied with glass ionomer cement (Ketac-Cem®) and a conventional adhesive (Right-on®) is described. Sandblasting of the bracket base was undertaken in half of the sample bonded with Ketac-Cem and produced a significant reduction in the probability of failure relative to the unsandblasted sample. Brackets with sandblasted and unsandblasted bases, bonded with Ketac-Cem were subjected to mechanical fatigue in a ball mill for a total of 20 hours. Mean survival time (MST) was then calculated for each group and was found to be significantly improved by sandblasting of the bracket base (P <0·01).