OrthoCAD: digital models for a digital era.
(73/340)
This article describes the use of OrthoCAD--a digital study model capture, assessment and storage system. It is estimated that approximately 10% of orthodontists in USA and Canada now utilize digital study models, and improving technology is making it increasingly popular worldwide. The technology behind digital study models is briefly reviewed. The OrthoCAD system is described, and the advantages and disadvantages of using digital study models are highlighted. (+info)
Scratch hardness of stone models--measuring conditions.
(74/340)
This study investigated the effects of scratch load, scratch speed, and storage period of specimen on the scratch hardness of stone models. Types 4 and 5 stone specimens were made from vinyl silicone rubber and alginate impressions respectively. After specimens were stored in a desiccator with silica gel at room temperature for 24 hours or 1 week, scratches were created on the surface with three different scratch loads (1N, 2N, and 3N) and two different scratch speeds (50 and 100 mm/min). Then, the depths of scratches were measured. Scratch depth of stone specimens increased with increasing scratch load. Scratch depths of Type 4 stone specimens after 1-week storage were smaller than those after 24-hour storage at a speed of 100 mm/min. However, the effect of scratch speed on scratch depth did not follow a specific trend. (+info)
Combined cephalometric and stent planning for palatal implants.
(75/340)
Several aspects of palatal implant usage are technique sensitive. In particular, problems during the insertion stage may compromise implant osseo-integration, or its subsequent ease of handling and effectiveness. This paper describes a systematic approach to combined cephalometric and model planning, and subsequent stent fabrication for Orthosystem palatal implants. The authors recommend this protocol in order to optimize three-dimensional control of implant positioning, and to both simplify and standardize the insertion stage. (+info)
Average arch widths and associated changes between initial, post-treatment and post-retention measurements.
(76/340)
Computer image monitoring was used for evaluation of dental arch changes. A new special device captured geometrically calibrated images permitting comparison of several different dental casts. In the first part of this study 792 sets of study casts were screened. Measurements of dental arch width between reference points of canines, first premolars and first molars were made: upper jaw: men: canines: 35.1 +/- 0.13 mm; first premolars: 37.5 +/- 0.13 mm; first molars: 48.1 +/- 0.19 mm; women: canines: 33.4 +/- 0.13 mm; first premolars: 35.6 +/- 0.15 mm; first molars: 46.7 +/- 0.19 mm. In the second part of the study, changes between initial, post-treatment and post-retention alignment (5-years after orthodontic therapy) of upper and lower dental arch of 36 subjects were analyzed. Upper and lower arch compression in first premolars and molars area was visible before treatment. We conclude that computer image monitoring can be used for evaluation of dental arch changes during the different steps of treatment. (+info)
Educational material of dental anatomy applied to study the morphology of permanent teeth.
(77/340)
The purpose of this report is to present educational material that would allow the dental student to learn to easily identify the morphologic characteristics of permanent teeth, and how they fit together (occlusion). In order to do this, macro models of permanent teeth with no attrition were carved in wax and later molded with alginate. These molds were filled with plaster, dental stone and/or cold-cured acrylic resin. The large individual dental stone tooth models were mounted on a wax base, thus obtaining maxillary and mandibular arches which were occluded. These dental arches were molded with plaster or dental stone. The authors suggest that these types of macro models allow an excellent visualization of the morphologic characteristics of permanent teeth and occlusion. Dental students are able to carve the permanent dentition in wax with great facility when they can observe macro models. (+info)
Changes in clinical crown height as a result of transverse expansion of the maxilla in adults.
(78/340)
The risk of developing bony dehiscence and gingival recession may lead clinicians to prefer extraction to expansion in borderline cases. The purpose of this research was to compare changes in clinical crown height that occur at the buccal aspect of the maxillary lateral teeth of adult patients in which the transverse dimension was increased with those occurring if no expansion had been performed. Secondly it was the intention to identify factors increasing the risk of development of gingival recessions. The material comprised the pre- and post-treatment study casts from two groups of 50 adult patients. In one group an average transverse expansion of 3 mm was performed while in the other no change in the arch width was generated during treatment. Clinical crown heights of the two groups before and after treatment were compared with a Student's t-test and correlation analysis was used to determine whether any demographic or treatment-related parameters could be applied to predict an increase in clinical crown height. The increase in transarch width was greater in males (2.4-3.4 mm) than in females (1.8-2.5 mm), and greater at the level of the premolars than at the molars. No significant increase in buccal crown height could be identified. The increase in width was, however, related to buccal tipping as a positive correlation was found between the amount of expansion and tipping (P < 0.01). No detrimental effect of slow maxillary expansion could be demonstrated. (+info)
An approach to maintain orthodontic alignment of lower incisors without the use of retainers.
(79/340)
The purpose of this investigation was to examine the long-term stability of orthodontic alignment of lower incisors without the use of retainers. The study sample comprised 56 patients treated according to a protocol that included over-correction of rotated teeth at an early stage of treatment and systematic enamel reduction (stripping) of the approximal surfaces in the mandibular anterior region, both during treatment and follow-up. Care was also taken to maintain dental arch form and to avoid lateral expansion of the lower dental arch and proclination of the incisors. Dental study casts were obtained pre-treatment, at the end of treatment, and 3 years post-treatment. Alignment of the mandibular incisors was recorded using Little's irregularity index. The inter-canine distance and the sum of the mesio-distal widths of the mandibular incisors and canines were also measured. The total amount of enamel removed from the approximal surfaces of the lower anterior teeth ranged from 0.3 to 5.0 mm (mean 1.9 mm). The mean increase in irregularity index score of 0.6 from post-treatment to 3 years follow-up indicated good stability. In 45 per cent of the patients the change in score during this period was less than 0.5, indicating that the treatment approach presented may be considered an alternative strategy to placement of lower retainers to safeguard the stability of alignment of mandibular incisors. (+info)
Space conditions and dental and occlusal features in patients with palatally impacted maxillary canines: an aetiological study.
(80/340)
The aetiology of palatal canine impaction is unclear. The aim of this research was to investigate the occlusal features that could contribute to the aetiology of palatal maxillary canine impaction. The material consisted of the pre-treatment dental casts of 34 patients (27 female and seven male) with unilateral palatal canine impaction (impaction group). The average age of this group was 17.7 years (+/- 4.6). These were matched according to age, gender and type of malocclusion with a comparison group of pre-treatment dental casts from unaffected orthodontic patients. From the dental casts the following parameters were obtained: (1) dentoalveolar arch relationship, (2) missing or anomalous teeth, (3) the mesiodistal width of each maxillary tooth, (4) the upper arch perimeter, (5) the maxillary inter-premolar and inter-molar widths. The arch length-tooth size discrepancy was only calculated for subjects with no missing teeth. Palatal canine impaction occurred most frequently in subjects with a Class II division 2 malocclusion. There was an association between palatal canine impaction and anomalous lateral incisors (P = 0.01). The transverse arch dimension was significantly wider in the impaction group than in the comparison group (P < 0.01). There was no statistically significant difference in the mesiodistal width of maxillary teeth or in the arch length-tooth size discrepancy between the palatal canine impaction group and their matched comparisons (P > 0.05). These results suggest that the presence of an 'excess palatal width' and anomalous lateral incisor may contribute to the aetiology of palatal canine impaction. (+info)