A comprehensive national survey on malocclusion prevalence among Palestinian children.

BACKGROUND: This study aims to evaluate the prevalence of malocclusion and orthodontic features among schoolchildren in the West Bank, Palestine. METHODS: A stratified cluster sample of 1278 schoolchildren (620 males, 658 females, mean age 12 years and 5 months (± 0.5)) were examined. Candidates who had not received any previous orthodontic treatment were only included. Dental anomalies like missing and ectopic teeth were recorded. The anteroposterior occlusal relationship was assessed based on Angle classification. Overjet and overbite were measured. Crowding and spacing were recorded subjectively. In addition, crossbite, openbite, and midline displacement were recorded. The chi-square test and descriptive analysis were used statistically. RESULTS: The study found Angle Class I molar relationship in 65%, Class II div 1 in 17%, Class II div 2 in 6%, and Class III in 12% of the sample. An overjet (OJ) of more than 4 mm was present in 17%, and 4% had OJ of more than 6 mm; an OJ of at least 0 mm or less in 36%, and 6% had a reverse OJ. A normal overbite was observed in 53%, while 28% had an increase and 19% had a decreased overbite. An anterior openbite (AOB) was present in 9%, and a scissor bite or anterior crossbite in 6% and 14%, respectively. A posterior crossbite was observed in 12% (9% unilateral and 3% bilateral). Midline displacement was found in (9%). Crowding was observed in 35% and 31% and spacing in 24% and 15% of the maxillary and mandibular arches, respectively. A statistically significant relationship between gender and midline shift, a diastema, spacing in the upper arch, and most dental anomalies was found; males were more affected (p < 0.05). CONCLUSION: This study reported a high prevalence of malocclusion among schoolchildren in Palestine. A collaborative effort should be directed to obtain more monitoring and surveillance of malocclusion more frequently to prevent and control the exacerbation of the problem.

Mechanical properties of coated superelastic archwires in conventional and self-ligating orthodontic brackets.

INTRODUCTION: Coated archwires have been introduced to improve esthetics during orthodontic treatment. Our aim was to investigate the mechanical properties of coated superelastic archwires compared with conventional superelastic archwires with conventional and self-ligating brackets. METHODS: Four types of orthodontic archwires were investigated, 2 superelastic nickel-titanium and 2 coated Ultraesthetic archwires in 0.016-in and 0.018 x 0.025-in dimensions (all from G&H Wire, Greenwood, Ind). To achieve the same nominal size, the coated archwire is constructed from a smaller archwire that, when coated, reaches the nominal dimensions stated for the archwire. Conventional edgewise Orthos and Damon 2 self-ligating brackets (both from Ormco, Orange, Calif) were used with each wire. All specimens were tested in a universal testing machine in a 3-point bending test at a speed of 1 mm per minute and deflected for 2 mm. Loading and unloading forces were recorded and load-deflection curves plotted. RESULTS: Coated superelastic wires produced statistically significantly lower forces in loading and unloading when compared with the superelastic nickel-titanium wires at most archwire deflections (P <0.01). For nickel-titanium wires, loading values ranged from 189 to 1202 g, whereas the respective values for coated wires were 124 to 772 g. For all wires, an increase in size resulted in an increase in force. Interactions between wire type (coated or uncoated) and bracket type were observed. CONCLUSIONS: Ultraesthetic coated archwires produced lower force values in loading and unloading compared with uncoated wires of same nominal size. The Damon 2 self-ligating bracket system produced lower force values in loading and unloading. The lowest forces were generated by the combination of Ultraesthetic coated archwires and Damon 2 self-ligating brackets.

Ex vivo surface and mechanical properties of coated orthodontic archwires.

This study examined the mechanical and physical properties of retrieved coated nickel-titanium (NiTi) archwires compared with unused samples. Ultraesthetic 0.016 inch coated archwires (G&H(R) Wire Company) were investigated. Ten as-received wires were subjected to a three-point bending test using conventional and self-ligating bracket systems. Surface roughness of the coating was measured with a contact stylus profilometer. Optical and scanning electron microscopes were used to assess surface topography. Ten archwires were used in vivo for a period of between 4 and 6 weeks. Retrieved archwires were subjected to the same tests. The percentage of the remaining coating was calculated using digital photography. Coated archwires were used in vivo for a mean period of 33 days. Differences between the mean values of the as-received and retrieved archwires were determined using t-tests. In the three-point bending test, with conventional elastomeric ligation, retrieved wires produced a lower unloading force (P < 0.001). Both retrieved and as-received coated archwires produced zero values of unloading force when deflected for 4 mm. When tested using a self-ligating bracket system, retrieved and as-received coated archwires produced the same amount of force (P > 0.05). With surface profilometry, all measured roughness parameters (except R(sm)) had greater surface roughness for the retrieved coated archwires (P < 0.05). Under microscopy, retrieved coated archwires showed discolouration, ditching, and delamination. Only 75 per cent of the coating was present in retrieved coated archwires. Retrieved coated archwires produced lower unloading force values than as-received coated archwires with conventional ligation. Surface roughness of coated archwires increased after use. Coated archwires have a low aesthetic value, with 25 per cent of the coating lost within 33 days in vivo.