Robert N. Staley

Maxillary expansion: Clinical implications

Clinicians frequently expand the maxilla to correct certain malocclusions. The effects of expansion on facial structures, dentition, and periodontium are reviewed. The implications of these findings for the treatment of patients who need maxillary expansion are discussed.

Effect of a fluoride varnish on demineralization adjacent to orthodontic brackets

Home fluoride regimens have long been used to reduce the amount of demineralization adjacent to orthodontic appliances. In the absence of patient compliance, another method of applying the fluoride must be used. The purpose of this study was to evaluate, in vitro, the ability of a fluoride varnish, Duraflor, to directly inhibit demineralization of enamel surrounding orthodontic brackets. Brackets were bonded to 36 extracted human canines and premolars with a traditional composite resin and randomly assigned to three equal groups of twelve. Group 1 served as the control with no topical application after bonding. Group 2 was treated with a single application of a nonfluoridated placebo varnish. Group 3 was treated with a single application of Duraflor. All groups were cycled in an artificial caries challenge for 1 hour two times daily for 37 days and were brushed with a medium bristled toothbrush to simulate mechanical wear of the varnish. Demineralization of enamel was evaluated in longitudinal buccolingual tooth sections using polarized light microscopy. Both average depth and area of demineralization were measured with a sonic digitizer. ANOVA (P </=. 0001) and Duncans test (P </=.05) indicated significant differences in depth and area of demineralized enamel. Those teeth treated with Duraflor exhibited 50% less demineralization than the control teeth and an even greater difference when compared to the placebo group. Fluoride varnishes should be considered for use as a preventive adjunct to reduce enamel demineralization adjacent to orthodontic brackets, particularly in patients who exhibit poor compliance with oral hygiene and home fluoride use.

A comparison of arch widths in adults with normal occlusion and adults with Class II, Division 1 malocclusion

This study compares arch widths and other cast and cephalometric measurements of 36 normal-occlusion subjects (19 males, 17 females) with 39 Class II, Division 1 subjects (20 males, 19 females). None of the subjects had received orthodontic treatment. Analysis of variance demonstrated that subjects with normal occlusion had larger maxillary molar widths, maxillary canine widths, and maxillary alveolar widths than subjects with malocclusion; only male subjects with normal occlusion had larger mandibular molar widths and mandibular alveolar widths than the malocclusion subjects; the normal occlusion and malocclusion groups had similar mandibular canine widths; and when the lower molar and alveolar widths were subtracted from corresponding upper widths, the remainders of the Class II group were negative instead of positive, contrary to the normal group. This revealed a posterior crossbite tendency in the Class II group.

Enamel demineralization adjacent to orthodontic brackets bonded with hybrid glass ionomer cements: An in vitro study☆☆☆★

Enamel demineralization is recognized as a possible side effect of bonding orthodontic brackets with composite resins. Fluoride-releasing restorative materials have been shown to inhibit tooth demineralization. The purpose of this study was to evaluate two fluoride-releasing hybrid glass ionomer bonding agents for inhibition of enamel demineralization surrounding orthodontic brackets under two experimental conditions. This in vitro study used 72 extracted human premolars. Twenty-four teeth were bonded with Advance resionomer, 24 were bonded with Fuji Ortho LC hybrid glass ionomer and 24 were bonded with Transbond XT composite resin as the control. The teeth were cycled in an artificial caries challenge three times daily for 30 days. Half of the teeth in each group were brushed twice daily with a fluoridated dentifrice, and the other half were not brushed. Demineralization of enamel surrounding orthodontic brackets was evaluated with polarized light microscopy. Enamel lesions were photographed under maximum illumination. Images were projected, and demineralized areas were traced. Both average depth and area were measured with a sonic digitizer. Analysis of variance (P <.0001) and Duncans test (P <.05) indicated significant differences in depth and area of demineralized enamel such that lesion size was: Transbond XT no brush > Transbond XT brush > Advance no brush = Advance brush = Fuji Ortho LC no brush = Fuji Ortho brush. The promising results of this in vitro study warrant further clinical investigation of hybrid glass ionomer adhesives as orthodontic bonding agents to minimize enamel demineralization.

Anatomy of cusps of posterior teeth and their fracture potential

Fracture of cusps on posterior teeth, especially those carious or restored, is a major cause of tooth loss, Nonfunctional cusps fracture more often than the functional; mandibular cusps fracture more often than maxillary cusps. This study examined functional and nonfunctional cusps of the maxillary and mandibular posterior teeth in four different parameters; (1) buccolingual width, (2) angle of cuspal inclination, (3) thickness of enamel, and (4) angle of inclination of the dentinoenamel junction. Measurements of functional cusps, except those in maxillary premolars established differences that may explain the frequency of frequency of fracture. These parameters of functional and nonfunctional cusps suggest that the cuspal anatomy has a relationship to the fracture potential of cusps.

IN VITRO STUDY OF 24-HOUR AND 30-DAY SHEAR BOND STRENGTHS OF THREE RESIN-GLASS IONOMER CEMENTS USED TO BOND ORTHODONTIC BRACKETS

Interest in using composite resin-glass ionomer hybrid cements as orthodontic bracket adhesives has grown because of their potential for fluoride release. The purpose of this pilot study was to compare shear bond strengths of three resin-glass ionomer cements (Advance, Fuji Duet, Fuji Ortho LC) used as bracket adhesives with a composite resin 24 hours and 30 days after bonding. The amount of adhesive remaining on the debonded enamel surface was scored for each adhesive. Mesh-backed stainless-steel brackets were bonded to 100 extracted human premolars, which were stored in artificial saliva at 37 degrees C until being tested to failure in a testing machine. The hybrid cements, with one exception, had bond strengths similar to those of the composite resin at 24 hours and 30 days. Fuji Ortho LC had significantly lower bond strengths (ANOVA p < or = 0.05) than the other adhesives at 24 hours and 30 days when it was bonded to unetched, water-moistened enamel. Adhesive-remnant scores were similar for all cements, except for cement Fuji Ortho LC when it was bonded to unetched enamel. The resin-glass ionomer cements we tested appear to have bond strengths suitable for routine use as orthodontic bracket-bonding adhesives.

A revision of the Hixon and Oldfather mixed-dentition prediction method

A revision of the Hixon and Oldfather prediction method was undertaken with measurements obtained from persons who participated in the Iowa Facial Growth Study, the same group of subjects used originally by Hixon and Oldfather to develop their prediction equation. A significantly improved prediction equation was developed. A graph was made for clinical use in the prediction of mandibular canine and premolar widths in mixed-dentition patients.

Inhibition of enamel demineralization by an enamel sealant, Pro Seal: an in-vitro study.

INTRODUCTION Enamel demineralization adjacent to fixed orthodontic appliances compromises both esthetics and oral health. The purpose of this in-vitro study was to evaluate the effectiveness of a new enamel sealant, Pro Seal (Reliance Orthodontic Products, Itasca, Ill), on inhibiting enamel demineralization. Two materials that have demonstrated success in white spot prevention and do not require patient compliance were used for comparison. METHODS Thirty-two noncarious extracted molars were divided into 4 groups and received 1 of the following treatments: no treatment (control), fluoride varnish (Fluor Protector; Ivoclar Vivadent, Amherst, Mass), unfilled resin sealant (Delton; Dentsply Professional, York, Pa), and filled resin sealant (Pro Seal). The teeth were subjected to 15,000 simulated brush strokes followed by acidic challenge for 96 hours. They were examined macroscopically and sectioned for quantitative examination with polarized light microscopy. RESULTS All surface treatments provided statistically significant (P <.05) reductions in lesion depth compared with controls. Pro Seal performed significantly better (P <.05) than the other products, decreasing lesion depth by 97% compared with the controls and completely inhibiting lesion formation in 3 specimens. CONCLUSIONS Pro Seal shows promise as an effective method of preventing enamel demineralization without patient compliance.

Prediction of the mesiodistal widths of maxillary permanent canines and premolars

Multiple regression equations for prediction of the mesiodistal widths of the maxillary canines and premolars were developed for the right and left sides of the arches of males and females. The equations were developed from longitudinal data taken from ninety-two Caucasian children (forty-six boys and forty-six girls) who participated in the Iowa Growth Study. The multiple regression equations, when compared with three currently used methods of prediction, were the best predictors. The newly developed equations and other prediction methods currently in use were tested on longitudinal data taken from a sample of forty-three Caucasian orthodontic patients (sixteen males and twenty-seven females). Again, the multiple regression equations had the best performance.

Prediction of lower canine and premolar widths in the mixed dentition

The purpose of this investigation was to determine whether, with multiple regression analysis, a more accurate method than is now available for predicting the widths of unerupted mandibular canines and premolars of mixed-dentition patients could be developed. Regression analyses were performed on data derived from 83 Caucasian subjects (42 males and 41 females) who participated in the Iowa Growth Study. Measurements were taken on plaster casts of the mandibular incisors, canines, premolars, and first molars. Measurements of the mandibular canines, premolars, and first molars were obtained from periapical radiographs taken with a long-cone technique. Newly developed regression equations for each sex had the highest correlation coefficients and smallest absolute errors of estimate when compared to previously published methods. The new equations and previous prediction methods were tested on a sample of 55 orthodontic patients (23 males and 32 females). The newly developed equations were also the most accurate method of prediction in the orthodontic patient sample.