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Biomedical subjects

J A Canut

Publications and source records attributed to J A Canut.

18 recordsLinked to original sources
PubMed1999

Molarization of the lower second premolars.

This paper presents a case of extreme tooth variation. The patient was first observed during the mixed dentition period, when she presented a mild Class II malocclusion with increased overjet and acceptable overbite. In a panoramic radiograph, the presence of lower second premolars of disproportionate dimensions was discovered. When these oversized premolars erupted, the Class I malocclusion tended toward Class III, with an edge-to-edge bite. This created an unstable occlusion and the possible need for extractions.

Bicuspid↗
PubMed1999

In vitro comparison of the retention capacity of new aesthetic brackets.

Tensile bond strength and bond failure location were evaluated in vitro for two types of aesthetic brackets (non-silanated ceramic, polycarbonate) and one stainless steel bracket, using bovine teeth as the substrate and diacrylate resin as the adhesive. The results show that metallic bracket had the highest bond strength (13.21 N) followed by the new plastic bracket (12.01 N), which does not require the use of a primer. The non-silanated ceramic bracket produced the lowest bond strength (8.88 N). Bond failures occurred mainly between bracket and cement, although a small percentage occurred between the enamel-cement interface with the metal and plastic brackets and within the cement for the plastic bracket. With the ceramic bracket all the failures occurred at the bracket-cement interface. This suggests that the problems of enamel lesions produced by this type of bracket may have been eliminated. The results also show that the enamel/adhesive bond is stronger than the adhesive/bracket bond in this in vitro study.

Acid Etching, Dental↗
PubMed1999

A long-term evaluation of treated Class II division 2 malocclusions: a retrospective study model analysis.

Pre-treatment, end of treatment, and post-retention study models of 30 subjects with a Class II division 2 malocclusion were assessed, after a period of at least 3 years, in order to evaluate the long-term changes in occlusion, alignment, and arch dimensions. Molar relationship correction was found to be stable after retention. There were no variables which could be used to establish a prognosis of vertical stability. Over-correction of overbite was seen to relapse. Ten per cent of the cases showed unacceptable anterior maxillary irregularities after retention. Mandibular arch width and length usually showed a decrease after retention. An increase in lower intercanine width and arch length achieved by orthodontic treatment always relapsed. This relapse was associated with post-retention mandibular irregularity and crowding. Nine cases (30 per cent) showed an unacceptable degree of mandibular irregularity after retention. Pre-treatment crowding in the mandible showed a relationship with post-retention lower irregularity and crowding. There was a correlation between the number of years which had elapsed after retention, overbite relapse and post-retention mandibular irregularity.

Adolescent↗
PubMed1997

Comparison of the changes in facial profile after orthodontic treatment, with and without extractions.

A study was made of 31 patients with Angle Class II malocclusion. Fifteen patients did not undergo extraction of teeth (Group A), while 16 underwent extractions of four premolars (Group B). Data was obtained from the corresponding lateral radiographs of the head taken both before and after orthodontic treatment. The main aim of the study was to compare the response of the soft and hard tissues of the facial profile in Class II malocclusion treated with the extraction of four premolars and the response of borderline cases presenting with similar malocclusions, but not subjected to extraction. In this latter group reasonable doubt existed as to whether or not to remove teeth in order to solve the occlusal and aesthetic problems. It is concluded that significant hard tissue differences between the groups at the end of treatment were limited to a more retruded position of the incisors and a reduced overbite amongst those patients subjected to extraction. The main soft tissue differences between the groups at the end of treatment were a more retruded lower lip and a more pronounced lower labial sulcus in those patients subjected to extraction.

Adolescent↗
PubMed1996

Mandibular incisor extraction: indications and long-term evaluation.

The extraction of a lower incisor constitutes a therapeutic alternative limited to certain occlusal situations, i.e. supernumerary incisors, tooth size anomalies (peg-shaped upper laterals), ectopic eruption and anterior crossbites. The effect of the extraction of a single incisor on the out of retention alignment of lower anterior teeth was studied in 26 treated cases. Initial (T1), final (T2) and 5-8 years out of retention (T3) dental casts were measured. Mean crowding at the start of treatment (T1 = 3.86 mm) relapsed out of retention (T3 = 1.49 mm), with a net mean improvement of 2.37 mm. Little's irregularity index at the start of treatment (T1 = 6.44) relapsed out of retention (T3 = 2.53), with a net mean improvement of T1-T3 = 3.91. Alignment stability seems to be better than that achieved in cases subjected to premolar extraction.

Adolescent↗
PubMed1995

Changes in the upper airway of patients who wear a modified functional appliance to treat obstructive sleep apnea.

This study was designed to investigate changes that occur in the upper airway of patients with obstructive sleep apnea who use a modified functional appliance. The experimental group included 10 men, all diagnosed with obstructive sleep apnea. Nuclear magnetic resonance imaging was carried out on each patient. One image was taken when the patient was in maximum habitual occlusion and another was taken while the patient wore the appliance. From the images gained, a three-dimensional reconstruction of the upper airway from the palatal plane was achieved. The images revealed statistically significant increases in the volume of the upper airway with the use of a modified functional appliance. Three-dimensional studies of the upper airway show greater detail and therefore seem likely to have more validity than two-dimensional studies.

Adult↗
PubMed1990

Effects of maxillary protraction determined by laser metrology.

In this work we studied some of the main effects of the maxillary protraction orthopedic device. The initial dento-craniofacial reactions induced by maxillary protraction similar to that commonly employed in clinical practice are reported. The fringe counting holographic interferometry technique is used to measure displacements. The experiments were performed on a dried human skull; traction application points were situated over the permanent lateral incisors or over the first permanent molars. The results fundamentally reveal an anterior rotation of the dentomaxillary complex, more intense when traction is applied to the lateral incisors, as shown by a more marked extrusion of the molars in this case. Moreover, major deformation patterns could be observed in inner hard structures of the skull base when applying orthopaedic forces.

Child↗
PubMed1975

Clinical management of the mandibular molars.

The complex variety of clinical problems posed by the lower molars requires maximum care in diagnosis and in treatment planning. In this article several therapeutic solutions to these problems are presented. The need to treat positional anomalies of the second molars and to control their drifting in cases of bracing and mandibular insertion, may be an effective auxillary means of treatment of those malocclusions in which lengthening of the dental bracing zones is indicated.

Bicuspid↗