Influence of bio-lubricants on the orthodontic friction.

The Friction force of Stainless Steel (SS) and Nickel-Titanium (Ni-Ti) rectangular archwires against stainless steel brackets was investigated. Two types of brackets were used namely: Self-ligating brackets (SLB) and conventional brackets (CB). The friction tests were conducted on an adequate developed device under dry and lubricated conditions. Human saliva, olive oil, Aloe Vera oil, sesame oil and sunflower oil were used as bio-lubricants. The friction force was examined as a function of the ligation method and oil temperature. It is found that under oil lubrication, the friction behavior in the archwire/bracket assembly were the best. The SLB ligation was better than the conventional ligation system. The enhancement of the frictional behavior with natural oils was linked to their main components: fatty acids.

[Is it necessary to treat incisal protrusion in Tunisian children?]. / Faut-il traiter la biprotrusion des enfants tunisiens?

It is thought that incisor protrusion could be ethnic-related because Tunisians, as Africans, might reflect the genetic influence of the incisal protrusion of their darker skinned neighbors. We first compiled local standards by determining the normal incisor positions of children of the Sfax region with balanced facial patterns. We selected 95 teenagers from 5 different high schools in Sfax (average age: 16 years 9 months), all having a normal dentition and a balanced facial pattern. This first study showed that upper and lower incisors were protruded 3 mm beyond American standards. Second, we studied incisor stability after four-first bicuspid extraction treatment. We selected 26 patients all having Class I molar relationships and upper and lower incisor protrusion. We compared x-ray incisor measurements of 3 radiographs: before treatment, after treatment and 2 or 3 years post-treatment. This study shows that incisor relapse ranges between 20 and 30%.