William A. Wiltshire

Shear bond strengths of a glass ionomer for direct bonding in orthodontics

This study was undertaken to compare the shear bond strengths of mesh-backed orthodontic buttons bonded to human enamel using a glass ionomer marketed for direct bonding in orthodontics, both in conjunction with, as well as without, enamel etching and to compare the results with a no-mix composite bonding resin. Freshly extracted noncarious human premolar crowns were used, to which mesh-backed metal orthodontic buttons were bonded to the lingual surfaces with one of three methods: group 1, glass ionomer without enamel etching; group 2, glass ionomer with enamel etching; and group 3, with a no-mix orthodontic bonding resin with enamel etching. After being stored in water for 48 hours at 37 degrees C, the samples were tested to failure in an Instron with the Bencor testing system. The data were statistically analyzed with the Mann-Whitney U test. The debonded specimens were visually inspected in respect of failure mode. The no-mix bonding resin had a significantly higher shear bond strength than the glass ionomer cement. Enamel etching with 37% orthophosphoric acid increased the mean shear bond strength of the glass ionomer, however, not significantly. Less cement remained on enamel after debonding when the glass ionomer was used when compared with residual resin when the no-mix bonding resin was used. Clinical research by several investigators is advised to determine the bond failure rate of glass ionomers when used in conjunction with orthodontic bracket bonding.

Manual and computer-aided space analysis: a comparative study.

Recently, computers have been used to measure key landmarks from photocopies of upper and lower study models to increase simplicity, accuracy, and informatics. This is a comparative study to evaluate the accuracy and reliability of computer-aided space analysis. Data were collected from a series of randomly selected study models. All subjects had Angle Class I molar relationships with minor malocclusions such as crowding, rotations, or diastemas. Two investigators independently measured teeth on models with a Vernier gauge that had sharpened caliper tips. Intraexaminer and interexaminer reliability was determined at 0.2 mm. All teeth, to and including the first molars, were measured. Two photocopies of each set of models were made on a photostat machine (Xerox, Japan) and were coded. A template with a ruler was used, to allow the investigator to compensate for any reduction or enlargement error during the photocopying process. The mesiodistal sizes were measured with a digitizer, and results were processed by using a dedicated computer program. Evaluations were done in a double-blind manner. The nonparametric Wilcoxon signed rank test for paired observations to compare median differences between measurements was used. Intraexaminer digitized measurements were almost identical and differed (p < 0.0001) for only one measurement. However, interexaminer manual and digitized measurements differed significantly (p < 0.001) for 20 of the 24 teeth. Nineteen of these digitized tooth measurements were smaller. The mean arch length measurements differed by 4.7 mm (p < 0.0001) in the maxilla and by 3.1 mm (p < 0.0001) in the mandible. The difference between the manual and digitized analyses may be due to the photocopying process. The inability to accurately measure a three-dimensional study cast that has been duplicated in two dimensions, convex structure of teeth, curve of Spee, tooth inclination, and tooth position may play a role. The computer-aided measuring system is reliable, but accurate mesiodistal measurements cannot be made from photocopies of dental models. Manual measurements that use a calibrated gauge produce the most accurate, reliable, and reproducible results.

Determination of fluoride from fluoride-releasing elastomeric ligature ties

Unaesthetic white spot lesions or larger unsightly areas of decalcification around orthodontic brackets remain a significant problem during fixed appliance treatment. This study determined the in vitro fluoride release from 200 fluoride-containing elastomeric ligature ties. With the potentiometric analytic method, the fluoride release was determined in distilled water, for 10 groups of 20 elastomerics, representing the clinical usage in a patient. Readings were taken every 24 hours for 5 days and then every second week for 6 months. The data were analyzed with the Wilcoxon matched pairs signed ranks test. Fluor-I-Ties (Ortho Arch Company Inc., Hoffman Estates, III.) released significant amounts of fluoride compared with the control readings. The fluoride release was characterized by an initial burst of fluoride during the first day and second day, followed by a logarithmic decrease. By the end of the second week 88% of the total fluoride had been leached from the elastomerics, but adequate magnitudes of fluoride were released over the remainder of the test period to aid theoretically in the prevention of demineralization and enhance remineralization of enamel through calcium fluoride and fluorapatite formation. For optimum clinical benefit, Fluor-I-Ties should be replaced monthly. Future prospective longitudinal clinical studies are indicated.

Fluoride release from four visible light-cured orthodontic adhesive resins

Decalcification of enamel during fixed orthodontic appliance treatment remains a problem. This study determined the in vitro fluoride (F) release from four light-cured orthodontic adhesives since cariostatic potential of such adhesives is related to their F releasing ability. Two nonfluoride and two fluoride-containing adhesives were tested. By means of the potentiometric analytical method, the F release of each resin was determined daily for 7 days and thereafter weekly for a month and then monthly until week 85. The data were analyzed with Kruskal-Wallis, Mann-Whitney, and Wilcoxon matched-pairs tests. The F release of all the resins were characterized by an initial burst of F release during the first day, followed by a tapering down in magnitude. FluorEver (MacroChem, Billerica, Mass.) outperformed the other adhesives in all aspects of F release and continued to release F for up to 85 weeks. Fluorapatite formation resulting from F release from orthodontic adhesives could be more advantageous in reducing decalcification during fixed appliance treatment than other preventive modalities.

Nickel allergy and orthodontics, a review and report of two cases

Nickel is a common component in many orthodontic materials. An allergy to nickel is commonly seen in the population, more frequently in women. This allergy has increased with the more frequent use of nickel containing jewellery and intraoral piercings. As a result, this allergy can be expected to be more readily encountered in dental practice. Possible allergy to nickel should be a question in the initial patient health history questionnaire. The dental practitioner should be mindful of this allergy during the course of orthodontic treatment, and know how to diagnose a nickel allergy if it appears and subsequent action in treatment and referral if it is suspected. This paper provides a summary of nickel allergy, its epidemiology, diagnosis and recommendations and alternatives to treatment. A detailed description of two cases where it was discovered in orthodontic patients is also reported.

In vitro and in vivo fluoride release from orthodontic elastomeric ligature ties

Clinically, demineralization of enamel around orthodontic attachments can occur after only 1 month. Fluoride incorporation into elastomeric ligature ties may provide additional protection against decalcification through fluoride release. This study compared the fluoride release of fluoride-impregnated and nonfluoride elastomeric ligature ties (Ortho Arch Company) both in vitro and in vivo. A total of 260 fluoride-impregnated and 260 nonfluoride elastomerics were evaluated in this study, 400 in vitro and 120 in vivo. For the in vivo part of the study, six patients had fluoride and nonfluoride elastomerics placed in cross-quadrant fashion in their mouths; these were removed and tested for residual fluoride release after 1 month. With the use of the potentiometric analytical method, the fluoride release of the elastomerics was determined in distilled water as the 24-hour residual release, to compare the in vitro and in vivo fluoride leached into solution. The data was analyzed with the Wilcoxon matched-pairs signed ranks test. The distilled water control yielded an F- reading of 0.03 +/- 0.01 microgram/F/mL. In the in vitro part of the study, an average of 0. 38 microgram/F/mL/elastomeric was released over the 1 month period by the fluoride-impregnated elastomerics; this decreased significantly (P <. 05) to a 24-hour residual value at 1 month of 0.02 microgram/F/mL/elastomeric ligature, which is in the same order of magnitude as the distilled water control solution. The nonfluoride ties produced a calculated 24 hour residual fluoride release of 0. 003 microgram/F/mL/elastomeric after 1 month; this is much less than the distilled water control and would not be possible to measure accurately. After 1 month in vivo, significantly greater (P >.05) amounts of 24-hour residual fluoride were apparent: F- elastomerics = 1.43 microgram/F/mL/elastomeric and nonfluoride elastomerics = 0.44 microgram/F/mL/elastomeric. Fluoride ties gained weight intra-orally. Residual, leachable fluoride was present in fluoride-impregnated and nonfluoride elastomeric ligature ties after 1 month of intraoral use, due to imbibition. The clinical efficacy of fluoride-impregnated elastomeric ligature ties to prevent decalcification in the presence of plaque needs to be investigated.

Profile changes in orthodontic patients treated with mandibular advancement surgery

INTRODUCTION The potential to improve facial esthetics is often the deciding factor in treatment planning of borderline orthodontic patients who can be treated with either orthognathic surgery or dental camouflage. The purpose of this study was to determine the degree of skeletal and soft-tissue Class II disharmony necessary before a significant esthetic benefit is derived from mandibular advancement surgery. METHODS Twenty laypeople, 20 orthodontists, and 20 oral surgeons rated the attractiveness of before and after treatment profiles of 20 mandibular advancement patients using a 5-point Likert scale. The Spearman rank correlation tested for relationships between amount of profile change and varying pretreatment ANB and profile angles. Plots of the distribution of profile changes with varying ANB and profile angles were then examined. RESULTS There was a tendency for inverse correlations between profile change and profile angle, and for positive correlations between profile change and ANB angles, but only the relationship between profile change and ANB angles judged by the orthodontists was statistically significant (P <0.05). Orthodontists, oral surgeons, and laypeople found that profiles consistently improved when profile angles were < or = 159 degrees, < or = 158 degrees, and < or = 157 degrees, respectively. Orthodontists and oral surgeons found profiles consistently improved when ANB angles were > or = 5.5 degrees and > or = 6.5 degrees, respectively, whereas laypeople showed no trend between ANB angle and profile change. The incidence of having less desirable profiles after treatment was 2.6 to 5.0 times higher when the pretreatment profile angles were larger than the threshold profile angles, and 4.5 to 7.9 times higher when the pretreatment ANB angles were less than threshold ANB angles. CONCLUSIONS Pretreatment profile angles < 160 degrees and ANB angles > 6 degrees are necessary for profiles to be consistently perceived as improved after surgery and to minimize the incidence of the profile worsening after treatment.

Future practice plans of orthodontic residents in the United States

INTRODUCTION The purpose of this study was to investigate the future clinical practice plans of orthodontic residents in the United States. METHODS All program chairs and directors of the 65 US orthodontic residency programs were contacted by e-mail and telephone and asked for permission to e-mail their residents and invite them to take part in an anonymous 57-item questionnaire online. A total of 335 e-mails from 37 programs were obtained, and the survey was sent in May 2007. Basic statistics including chi-square comparative analyses were performed by sex, age, and year of program. RESULTS A total of 63.04% of orthodontic residents plan to use self-ligating brackets; 84.06% plan to use Invisalign (Align Technology, Santa Clara, Calif); 92.03% plan to use temporary anchorage devices, and 72.26% plan on placing them themselves; 28.26% plan to use cone-beam computerized tomography; 92.75% plan to use a digital imaging program; 45.65% plan to use indirect bonding; and 10.87% plan to use lingual orthodontics. A total of 70.07% plan to use 2-phase treatment, and 61.59% said they will use functional appliances. A total of 81.16% plan to become certified by the American Board of Orthodontics, but only 18.12% thought certification should be mandatory for licensure; 36.50% indicated that a master of science degree should be required in their program, and 77.94% believe that a 24- to 30-month program adequately prepares them for future orthodontic practice. CONCLUSIONS Newer orthodontic technologies such as self-ligating brackets, temporary anchorage devices, and Invisalign as well as functional appliances are expected to grow in popularity in the United States because of projected future use by orthodontic residents. Two-phase orthodontic treatment with functional appliance mechanics will continue to be used. Most orthodontic residents will become certified by the American Board of Orthodontics but do not believe it should be necessary for licensure. Orthodontic residents in the United States believe that a 2-year program adequately prepares them for private practice.

In Vivo Bonding of Orthodontic Brackets to Fluorosed Enamel using an Adhesion Promotor

OBJECTIVES To determine the success of bracket retention using an adhesion promoter with and without the additional microabrasion of enamel. MATERIALS AND METHODS Fifty-two teeth with severe dental fluorosis were bonded in vivo using a split-mouth design where the enamel surfaces of 26 teeth were microabraded with 50 microm of aluminum silicate for 5 seconds under rubber dam and high volume suction. Thirty-seven percent phosphoric acid was then applied to the enamel, washed and dried, and followed by placement of Scotchbond Multipurpose Plus Bonding Adhesive. Finally, precoated 3M Unitek Victory brackets were placed and light cured. The remaining teeth were bonded using the same protocol but without microabrasion. RESULTS After 9 months of intraoral service, only one bond failure occurred in the control group where microabrasion was used. Chi-square analysis revealed P = .31, indicating no statistical significance between the two groups. CONCLUSIONS Bonding orthodontic attachments to fluorosed enamel using an adhesion promoter is a viable clinical procedure that does not require the additional micro-mechanical abrasion step.

Impact of orthodontic retainers on periodontal health status assessed by biomarkers in gingival crevicular fluid.

OBJECTIVE To evaluate whether biomarkers of inflammation and periodontal remodeling are differentially expressed in the gingival crevicular fluid (GCF) of patients wearing different types of orthodontic retainers. MATERIALS AND METHODS Thirty-one adult subjects (17 men and 14 women with an age range of 20 to 35 years) were allocated to three different groups. Group 1 consisted of 10 patients wearing fixed retainers, group 2 included 11 patients using lower removable retainers, and group 3 comprised 10 patients without retainers (control). Periodontal health assessment and GCF collection were carried out at two sites per subject: the lingual side of a central lower incisor and the lingual side of a lower second premolar. Aliquots from diluted GCF were screened for the presence of biomarkers using a microarray technique. RESULTS Group 1 patients exhibited a higher percentage of sites with visible plaque in the incisor region than the other groups (P = .03); no differences were noted in gingival bleeding and probing depths. The median concentrations (pg/mL) of interferon-gamma and interleukin-10 were significantly higher in the premolar sites of patients in group 2 (P = .01 and P = .04, respectively), whereas the concentration of matrix metalloproteinase-9 was significantly higher at the incisors of patients wearing fixed retainers (P = .02). A significant difference between the two sites was seen only in group 2. CONCLUSIONS The presence of different orthodontic retainers may promote specific alterations in the GCF composition. With retention periods potentially becoming longer, this finding may be of clinical significance.