Validity, reliability and reproducibility of three methods used to measure tooth widths for bolton analyses.

BACKGROUND: Vernier calipers have traditionally been used as the 'gold-standard' for tooth width measurements. New digital methods may prove to be as valid, reliable and reproducible as caliper measurements. AIMS: To determine the validity, reliability and reproducibility of mesiodistal crown measurements made with calipers, using the DigiModel method and on digital photographs, and to determine the validity, reliability and reproducibility when the measurements are employed in Bolton tooth size analyses. METHODS: Twenty-five consecutive study models were used. The maximum mesiodistal crown widths of 12 teeth in each arch (first molar to first molar) were measured with digital calipers, using the DigiModel software (OrthoProof, Caulfield South, Victoria, Australia) and on standardised digital photographs of the models by eight examiners. One examiner measured all models three times using the three measurement methods, two examiners measured all models once using the three measurement methods and five examiners measured all models once using the calipers only. Validity for the widths of individual teeth, the mean tooth width and the Bolton ratios were assessed using a general linear model two-way analysis of variance and pair-wise comparisons between the two digital methods and the calipers. Reliability was assessed with Cronbach's alpha and reproducibility with the intra-class correlation coefficient. RESULTS: There were statistically significant differences between the tooth widths measured with DigiModel and the calipers (p < 0.001) and with the calipers and digital photographs (p < 0.001). However these discrepancies were judged not to be clinically significant. The Cronbach's alpha scores for all methods were classified as 'excellent'. The intra-class correlation coefficient values exceeded 0.75 for the digital calipers, 0.79 for DigiModel and 0.54 for the digital photographs. CONCLUSIONS: The validities of DigiModel and digital photographs for tooth width measurements and Bolton analyses are clinically acceptable. The reliability of both methods is also excellent. However, DigiModel software provided more accurate Bolton's ratios and demonstrated greater reproducibility than the digital photographs.

Comparison of surgical and non-surgical methods of treating palatally impacted canines. I. Periodontal and pulpal outcomes.

BACKGROUND: Inferior periodontal and pulpal outcomes may follow surgical exposure of palatally impacted maxillary canines. OBJECTIVES: To compare the periodontal and pulpal health of palatally impacted maxillary canines following either surgical exposure and assisted eruption (SE) or unassisted eruption following extraction of the overlying deciduous canine and orthodontic creation of space in the arch (OT). METHODS: Twenty-eight subjects (OT group: N = 14; SE group: N = 14) with unilateral palatally impacted canines were examined at least six months after orthodontic treatment. The gingival index score, plaque index score, pocket depth, attachment loss, tenderness to percussion, pulpal responses to stimuli and radiographic assessment of changes in the pulpal cavities and peri-radicular areas were collected on the maxillary canines, lateral incisors and premolars. The contralateral teeth were used as controls. RESULTS: There were no significant differences in the plaque index scores, the gingival index scores or the periodontal outcomes between the impacted canines in the two groups (SE and OT). More impacted canines than control canines had lost some periodontal attachment in the SE group (p = 0.004). Although more lateral incisors, canines and premolars on the impacted side had partially obliterated pulps than the corresponding teeth on the control side, the teeth in both groups had similar pulpal responses (p = 0.064). CONCLUSIONS: Natural eruption and conservative surgical exposure with orthodontic alignment have minor effects on the periodontium. Impacted canines treated surgically and non-surgically had a higher prevalence of pulpal changes than the control canines. Ultimately, the choice of treatment may depend on the clinical indications, the patient's and the orthodontist's preferences.

Comparison of surgical and non-surgical methods of treating palatally impacted canines. II. Aesthetic outcomes.

BACKGROUND: Palatally impacted maxillary canines may appear unsightly after treatment because of changes in position and colour. AIM: To determine if palatally impacted canines treated either by surgical exposure and orthodontic repositioning or by creation of space in the arch and unassisted eruption have different aesthetic outcomes. METHODS: Twenty eight subjects with unilateral palatally impacted canines who had completed orthodontic treatment at least 6 months previously were recruited from three specialist practices. In 14 subjects the canines had been treated by surgical exposure, orthodontic extrusion and repositioning in the arch (SE group) and in the remainder the deciduous canines were extracted and excess space created in the arch for the canines to erupt naturally (OT group). The contralateral canines were used as controls. The mean pretreatment ages of the subjects in the SE and OT groups were 13.5 (SD:1.6) years and 13.5 (SD:1.3) years respectively. The position and colour of the canines were assessed on post-treatment study models and 35 mm slides using the American Board of Orthodontics Objective Grading System (ABO OGS) and subjective appraisal by two orthodontists. Each subject used a semantic scale to rate the aesthetic outcome of treatment. RESULTS: Sixty four per cent of the treated canines in the SE group were significantly more 'intruded' than the treated canines in the OT group (p = 0.004) and the control canines (p = 0.004). The ABO OGS grades of the canines in the SE and OT groups were similar (p = 0.173). While the assessors detected a lack of labial root torque and gingival margin changes in the canines in the SE group, the subjects in both groups were satisfied with the appearance of the canines post-treatment. CONCLUSIONS: Palatally impacted canines treated by surgical exposure, extrusion and orthodontic treatment were more likely to be displaced vertically ('intruded') after treatment than palatally impacted canines treated by extraction of the overlying deciduous canines and creation of excess space in the arch. Small occlusal and aesthetic changes detected by the orthodontists, but not the ABO OGS, did not appear to detract from the satisfaction of the subjects with the results of orthodontic treatment.

Predisposing factors to dental caries in children with cleft lip and palate: a review and strategies for early prevention.

OBJECTIVE: To review predisposing factors contributing to dental caries in patients with cleft lip, cleft palate, or both (CL/P). DESIGN: Patients with CL/P have a higher susceptibility to caries compared with the population group without clefts. A review of the literature was undertaken to determine factors that could account for the compromised oral hygiene and the high caries prevalence in patients with CL/P. RESULTS: After a literature review, modern strategies for the prevention of early childhood caries were developed and should be considered for integration into the overall management protocol of patients with CL/P. CONCLUSIONS: Preventive dental care is ever more so important in patients with CL/P compared with patients without clefts.

The influence of ligation on frictional resistance to sliding during repeated displacement.

OBJECTIVE: To determine if the type of ligation influences the frictional resistance between stainless steel wire and brackets when the wire is subjected to repeated vertical displacements. METHODS: Eight different types of ligation were used to secure a length of stainless steel wire in three stainless steel twin brackets. The wire was subjected to repeated vertical displacements in a simulated extraction space. Eighty per cent of the minimum force required to overcome static friction (F-m) between the wire and brackets was applied to the wire for eight minutes and any sliding measured. RESULTS: Frictional resistance to sliding was least when stainless steel ligatures twisted in a figure 8 pattern until taut then untwisted one quarter turn were used, and greatest when elastomeric modules in a figure 8 pattern (EM8) were used. The F-m difference between fully engaged standard and Super Slick elastomeric modules was significantly different (p = 0.007). The frictional resistance to sliding fell when the wire was secured with either of these two methods and subjected to vertical displacement loads. There was no significant difference in the rate of wire movement between these modules. CONCLUSION: Repeated vertical displacement reduced the frictional resistance to sliding for all methods of ligation except EM8.