Journal of Orthodontics

To investigate the association between certain occlusal anomalies and the occurrence and severity of dental caries in Brazilian preschool children.

Cross‐sectional study.

Twenty‐eight public nursery schools in Canoas, southern Brazil.

The study population comprised 890 three‐ to five‐year‐old children. Five trained and calibrated observers examined children for determination of decayed, missing and filled tooth (dmft) index (World Health Organization criteria including white spots) and orthodontic variables.

Caries severity (dmft) and caries occurrence (dmft⩾1).

Multivariable analysis was performed using Poisson regression with robust variance in order to determine the occlusal anomalies which represent risk factors for the occurrence of the binary outcome.

Caries severity was significantly higher among children without spacing in the maxillary anterior teeth (P = 0·001) and mandibular anterior teeth (P = 0·003) and among children without accentuated overjet (P = 0·023). The multivariable analysis demonstrated that children without spacing in maxillary anterior teeth had an increased risk of dental caries (prevalence ratio = 1·43; 95% CI, 1·05–1·93). Open bite, accentuated overjet and posterior cross‐bite were not associated with this outcome in the final model.

Absence of spacing in the maxillary labial segment represents a risk factor for dental caries in preschool children.

To evaluate the influence of autoclave sterilization on the fracture torque of five commercially available mini‐implants used for orthodontic anchorage.

In vitro laboratory study.

Ten mini‐implants from each of five different manufacturers were submitted to one cycle of autoclave sterilization and tested, compared to their control groups – consisting of 10 as‐received mini‐implants each – to assess their fracture torque values. The mini‐implants, connected to a digital torque gauge perpendicularly positioned to the bone surface, were inserted into swine femoral cortical bone segments until their fracture.

Maximum torque values.

A two‐way ANOVA to detect differences between implant products and the allocation group and one‐way ANOVA with the Tukey's honestly significant difference (HSD) post hoc test among autoclaved groups and among control groups separately to detect differences between manufacturers.

The effect of the autoclaving process was not significant (P = 0·411). The manufacturer factor, however, was significant (P<0·001). The one‐way ANOVA with the Tukey's HSD post hoc test results showed statistically significant differences between control groups.

The autoclave sterilization of the mini‐implants tested in this study did not affect their resistance to fracture; however, the mini‐implants from different manufacturers presented with statistically significant differences in their resistance to fracture.

To establish the Steiner's cephalometric norms for a Nepalese population, compare the gender and inter‐racial variations in dentoskeletal and soft tissue structures, and to test the null hypothesis that there are no racial differences in cephalometric measurements between Nepalese, Caucasians and other populations.

Prospective, cross‐sectional study.

One hundred and twenty lateral cephalograms of Nepalese subjects aged 16–21 years with class I normal occlusion and balanced facial aesthetics were selected. The cephalometric variables were measured. An independent one sample t test was used to compare the Steiner's ideal values with Indo‐Aryan Nepalese means and independent t test to compare Japanese means with Mongoloid Nepalese means and Mongoloids with Aryans. Intra‐investigator error was assessed with Lin's concordance method and the reliability of aesthetic evaluation of the photographs was tested with Cronbach's alpha.

Nepalese Mongoloid males possessed more protrusive lips (Z angle mean difference, 8°; P<0·001) than the Indo‐Aryan males. Mongoloid females had more protrusive mandible (SNB angle mean difference, 3·7°; P<0·001), greater class II skeletal bases (SND angle mean difference, 3·5°; P<0·001), longer SL length (mean difference, 5·6 mm; P<0·01), more proclined upper incisors (U1–NA mean difference, 6°; P<0·01) and a more protrusive lower lip (lower lip–S line mean difference, 0·9 mm; P = 0·003), lower lip–E line (2·0 mm; P<0·001) and Z angle (4·4°; P<0·001), than the Indo‐Aryan females. Differences between the Nepalese sample and published Caucasian and Japanese norms are also described.

Differences in the cephalometric values exist between the two ethnic groups in Nepal, as well as between our Nepalese sample and published Caucasians and Japanese norms. The norms published in this article will be useful when planning orthodontic treatment in Mongoloid and Indo‐Aryan individuals.

To compare the efficiency of orthodontic archwire sequences produced by three manufacturers.

Prospective, randomized clinical trial with three parallel groups.

Private orthodontic practice in Caloundra, QLD, Australia

One hundred and thirty‐two consecutive patients were randomized to one of three archwire sequence groups: (i) 3M Unitek, 0·014 inch Nitinol, 0·017 inch×0·017 inch heat activated Ni–Ti; (ii) GAC international, 0·014 inch Sentalloy, 0·016×0·022 inch Bioforce; and (iii) Ormco corporation, 0·014 inch Damon Copper Ni–Ti, 0·014×0·025 inch Damon Copper Ni–Ti. All patients received 0·018×0·025 inch slot Victory Series^TM brackets.

Mandibular impressions were taken before the insertion of each archwire. Patients completed discomfort surveys according to a seven‐point Likert Scale at 4 h, 24 h, 3 days and 7 days after the insertion of each archwire. Efficiency was measured by time required to reach the working archwire, mandibular anterior alignment and level of discomfort.

No significant differences were found in the reduction of irregularity between the archwire sequences at any time‐point (T1: P = 0·12; T2: P = 0·06; T3: P = 0·21) or in the time to reach the working archwire (P = 0·28). No significant differences were found in the overall discomfort scores between the archwire sequences (4 h: P = 0·30; 24 h: P = 0·18; 3 days: P = 0·53; 7 days: P = 0·47). When the time‐points were analysed individually, the 3M Unitek archwire sequence induced significantly less discomfort than GAC and Ormco archwires 24 h after the insertion of the third archwire (P = 0·02). This could possibly be attributed to the progression in archwire material and archform.

The archwire sequences were similar in alignment efficiency and overall discomfort. Progression in archwire dimension and archform may contribute to discomfort levels. This study provides clinical justification for three common archwire sequences in 0·018×0·025 inch slot brackets.

To evaluate the percentage force decay of elastomeric chain products utilizing three different design mechanisms simulating canine retraction; and to evaluate the percentage force decay of elastomeric chain products from four different companies.

In vitro, laboratory study.

LSUHSC Dental School, New Orleans, LA, USA.

Closed (non‐spaced), grey elastomeric chains from four companies were selected for the study. Three acrylic resin jigs were constructed to provide a framework for three simulated space closure mechanisms. The 6‐5‐3, the chain loop, and the 6‐3 were the configuration mechanisms used in the study.

An electronic force gauge was used to measure the percentage force decay associated with each elastomeric chain over 28 days at preselected times.

There was a significant difference in the mean percentage force decay for the three different mechanisms (P<0·001). For all four companies, the 6‐3 mechanical design had the smallest mean percentage force decay. There was a significant difference in the mean percentage force decay for the different companies (P<0·001). For all three mechanisms, Ormco had the smallest percentage force decay while Unitek had the highest percentage force decay.

The significant difference in the mean percentage force decay for the different mechanisms suggests that the 6‐3 design is a more efficient means of closing extraction spaces utilizing elastomeric chains.