Journal of Orthodontics

To investigate and compare the effects of superelastic nickel–titanium and multistranded stainless steel archwires on pain during the initial phase of orthodontic treatment.

A double-blind two-arm parallel design stratified randomized clinical trial.

A single centre in India between December 2010 and June 2012. A total of 96 participants (48 male and 48 females; 14.1±2.1 years old) were randomized (stratified on age, sex and initial crowding) to superelastic nickel–titanium or multistranded stainless steel archwire groups using a computer-generated allocation sequence.

We compared 0.016-inch superelastic nickel–titanium and 0.0175-inch multistranded stainless steel wires in 0.022-inch slot (Roth prescription) preadjusted edgewise appliances. The follow-up period was 14 days. Outcome was assessed with a visual analogue scale at baseline and 32 pre-specified follow-up points. Data was analyzed using mixed-effects model analysis.

One participant was lost to follow up and 10 were excluded from the analysis due to bond failure or incomplete questionnaire answers. Ultimately, 85 participants (42 males and 43 females; 14.1±2.0 years old) were analysed for the final results. No statistically significant difference was found for overall pain [F value = 2.65, degrees of freedom (df) = 92.6; P = 0.1071]. However, compared to multistranded stainless steel wires, pain in subjects with superelastic nickel–titanium archwires was significantly greater at 12 h (t = 2.34; P = 0.0193), as well as at day 1 in the morning (t = 2.21, P = 0.0273), afternoon (t = 2.11, P = 0.0346) and at bedtime (t = 2.03, P = 0.042).

For overall pain, there was no statistically significant difference between the two wires. However, subjects with superelastic nickel–titanium archwires had a significantly higher pain at peak level.

The aims of this study were to (1) investigate if there is a difference in skeletal maturation between tooth agenesis and control patients and (2) whether skeletal maturation is affected by the severity of tooth agenesis. The cervical vertebral maturation (CVM) index can be used to assess skeletal maturation.

A retrospective cross-sectional study.

Eastman Dental Hospital, London, UK.

A total of 360 cephalograms of patients aged 9–17 years (164 males and 196 females) allocated to four subgroups (mild, moderate and severe tooth agenesis patients, and controls) were assessed retrospectively. There were 90 patients in each of the four subgroups. The skeletal maturation of each subject was assessed both quantitatively and qualitatively using the CVM index. All patients in the study were either currently receiving treatment or had been discharged from the hospital.

There was no statistically significant relationship between skeletal maturation and the presence of tooth agenesis. Furthermore, there was no statistically significant relationship between the skeletal maturity of patients and different severities of tooth agenesis.

The data obtained from this group of patients and using this measurement tool alone does not supply sufficient reason to reject the null hypothesis. However, it suggests that it is possible that no difference exists between the groups.

To investigate whether there is an association between dental developmental anomalies (DDAs) and different manifestations of class II division 2 (CII/2) malocclusion incisor retroclination.

Retrospective comparative study.

Private orthodontic practice in the regions of Lisbon and Porto, Portugal.

The sample comprised 115 CII/2 malocclusions distributed into two groups on the basis of incisor retroclination: Group I composed of 48 CII/2 with retroclination exclusively of both maxillary central incisors; Group II composed of 67 CII/2 with retroclination of all four maxillary incisors. Using the initial orthodontic records, it was determined for each patient the presence of the following DDAs: tooth impaction, tooth agenesis, maxillary lateral incisor microdontia, tooth transpositions and supernumerary teeth.

Fifty-five per cent of patients were diagnosed with at least one of the DDAs studied. In the total sample the prevalence rates were: 20.0% of palatal maxillary canine impaction, 27.4% of third molar agenesis, and 15.7% of maxillary lateral incisor microdontia. No patient exhibited any transposition or supernumerary teeth. The distribution of the DDAs studied by groups revealed a strong association of palatal canine impaction, tooth agenesis and maxillary lateral incisor microdontia with Group II but not with Group I.

The association of DDAs with CII/2 malocclusion is not common to all types of maxillary incisor retroclination, suggesting different etiologic factors among the different manifestations of CII/2 incisor retroclination.

The main objective of this in vivo study was to determine the incidence and location of fracture in round nickel–titanium (NiTi) and round stainless steel orthodontic archwires, both commonly used in orthodontics. Secondarily, this study sought to determine if there is any correlation between archwire fracture and gender, diameter of the archwire, arch type (maxillary/mandibular) or bracket used.

In vivo study.

One thousand orthodontic patients (1434 archwires) were evaluated during regular treatment visits to assess archwire fracture and location. The patient's gender, age, type of archwire (round NiTi and round stainless steel), diameter of the archwire, arch type, location of fracture (anterior or posterior) and period of service before fracture were recorded.

Chi-square statistical test was utilized to address the frequency and the correlation between the different variables. Level of statistical significance (α) was set at 0.05.

Twenty-five archwire failures were reported (1.7%) of the total sample size. All fractured archwires were NiTi, and 76% of the fractures were located in the posterior region. No statistical significance was found between archwire fracture and gender, arch type (maxillary/mandibular), archwire diameter or bracket type.

The frequency of archwire fracture during regular orthodontic visits is very low. The most common archwire fracture site is the posterior region. NiTi wires are the most commonly fractured archwire. No statistically significant correlation exists between archwire fracture and gender, arch type, bracket type or diameter of archwire.

The aim of this study was to investigate changes in the lip-line in asymmetrical cases treated with mandibular osteotomy alone.

Retrospective study.

Hiroshima University Institute of Biomedical & Health Sciences, Hiroshima, Japan

The subjects in this study consisted of 30 patients with an altered lip-line inclination who underwent isolated mandibular osteotomy (bilateral or unilateral sagittal split ramus osteotomy or intraoral vertical ramus osteotomy) as part of their surgical correction. Frontal cephalograms and facial photographs, taken at the first examination and after treatment, were used to measure changes in the inclination of the lip-line and cant of the occlusal plane, as well as the lateral deviations of hard and soft tissue Menton.

Inclination of the lip-line after active treatment was significantly improved compared with that before treatment. Menton on the hard and soft tissues after active treatment also experienced a significant improvement compared with its position at first examination.

One-jaw mandibular osteotomy is able to improve the inclination of the lip-line even in the presence of an occlusal cant. The inclination of the lip-line is corrected in association with sufficient lateral movements of Menton on the mandible.

To evaluate retention protocols and use of vacuum-formed retainers (VFRs) among specialist orthodontists.

Postal/electronic (e-) questionnaire.

Republic of Ireland.

Members of the Dental Council of Ireland Specialist Register of Orthodontists and/or Orthodontic Society of Ireland.

A pilot-tested questionnaire was distributed to 123 eligible specialist orthodontists. Questions addressed respondent demographics, preferred retainer choice in the maxillary and mandibular arches, prescribed wear protocols, VFR characteristics and factors influencing retainer choice. Statistical analyses were performed using PASW® version 18.

The response rate was 82%. VFRs were the most commonly chosen retainer, prescribed by 53% of respondents in the maxilla and 33% in the mandible. Full-time followed by part-time wear of removable retainers (RRs) was the wear protocol favoured by the majority (70–76%). Full occlusal coverage was the VFR design favoured by 93%. VFR sheet thicknesses of 1.0 mm (68%) and 0.75 mm (16%) were most commonly prescribed. Seventeen per cent were aware that their patients used their VFRs as a receptacle for dental bleaching gel. Life-time wear of retainers was advised by 67–78%. The operator factor that most influenced retainer choice was the pre-treatment situation (88%).

VFRs were the most common retainer choice in the maxilla and mandible with full-time wear followed by part-time wear of RRs favoured by most. Full occlusal coverage with a thickness of 1.0 mm was the VFR design prescribed by the majority. More than one in six specialist orthodontists were aware that their patients used their VFRs as a receptacle for dental bleaching gel.