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ABSTRACT: Guidelines have been established for the arrangement of artificial teeth based on the curve of Wilson, the curve of Spee and
the occlusal plate rule of Gysi. However, no scientific studies have been carried out to see whether these prosthodontic rules
are actually present in natural teeth. This study was carried out on a selected sample of children and adolescents with natural
dentitions using a 3D computer-aided measuring device to reevaluate these occlusal rules in order to establish whether occlusion
with anterior protected articulation is the occlusal scheme of choice. The previously estblished prosthodontic rules were
confirmed to be present in the complete natural dentitions of adolescents at completion of tooth eruption period and support
their use as guiding principles in diagnosis and treatment.
KeywordsAdolescent–Dental occlusion–Dental models–Occlusal guidance–Occlusal wear
international journal of stomatology & occlusion medicine 04/2012; 4(1):20-27.
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ABSTRACT: Long-term stability is an important measure of the success of orthodontic treatment. Research in the 1970s suggested that premolar extraction treatment had poor stability over the long term. The purpose of this prospective follow-up study was to investigate changes in intercanine widths and the irregularity index during the postretention phase in patients treated with and without extractions. Associations between the maxillary canine guidance angle and the mandibular intercanine widths and the mandibular irregularity index were also examined.
Two groups of 30 patients each, with and without premolar extractions, were studied and the results compared. Records were taken at pretreatment, at bracket removal, at the end of retention, and out of retention. The times out of retention were 6.3 years for the nonextraction group and 6.5 years for the extraction group. Stone casts were mounted on an articulator with an anatomical facebow and a central wax record. The measurements were made with a 3-dimensional digitizer.
Maxillary and mandibular intercanine distances behaved differently. The mandibular intercanine distance showed a net decrease between pretreatment and follow-up, whereas the maxillary arch had a net increase. The maxillary canine guidance angle at the end of retention, measured to the axis-orbital plane, was highly associated with relapse of mandibular anterior alignment and change of the mandibular intercanine distance.
Methods are needed that consider the anatomical configuration of the teeth for bracket selection before treatment. Individualized brackets (torque) should then be coordinated with the guidance angle of the maxillary teeth.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 06/2008; 133(5):669-80. · 1.33 Impact Factor
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ABSTRACT: Mechanical axiography was performed on 49 (37 female, 12 male) patients prior to orthodontic treatment, after removal of the fixed appliance, and at the end of retention. Twenty-five subjects (mean age 12.8 years) underwent orthodontic treatment without premolar extractions (group 1) and 24 subjects (mean age 13.5 years) with premolar extractions (group 2). The axiographic tracings of the protrusive movements were analysed using a digitizer and specially designed software. A statistically significant increase (P < 0.05) in the values for horizontal condylar inclination (HCI) was found for both groups over the entire observation period. Group 1 showed a higher increase (P < 0.05) between the beginning of treatment and removal of the brackets, and group 2 between bracket removal and the end of retention. At the end of retention, a similar increase in HCI values was found for both groups. Over the observation period, the frequency of pathological axiographic findings decreased, which seems to be a positive effect of orthodontic treatment.
The European Journal of Orthodontics 08/2004; 26(4):427-33. · 0.89 Impact Factor
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ABSTRACT: The purpose of this study was to investigate changes in arch length, arch area, and irregularity index in patients treated with and without premolar extractions. Records collected at pretreatment, at bracket removal, at the end of retention, and 5 years out of retention were examined. Stone casts were mounted on an articulator with an anatomic face-bow and a central wax record, and measurements were made with a 3-dimensional digitizer. In general, the maxillary arch exhibited less relapse tendency than did the mandibular arch for both patient groups. In general, the extraction group showed the same relapse tendency as the nonextraction group.
American Journal of Orthodontics and Dentofacial Orthopedics 08/2004; 126(1):71-81. · 1.38 Impact Factor
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ABSTRACT: The purpose of this study was to investigate the changes in palatal volume and palatal height in patients treated with and without premolar extractions. Records were collected at pretreatment, at bracket removal, at the end of retention, and 5 years out of retention. Stone casts were mounted in a SAM 2 articulator with an anatomic face-bow and a central wax record, and measurements were made with a 3-dimensional digitizer. The hypothesis, that orthodontic treatment with premolar extractions changes the palatal form, was verified. Increases in palatal volume and height were demonstrated in the nonextraction group. The extraction group showed a decrease in palatal volume but could compensate for some loss by an increase in volume in the anterior segment.
American Journal of Orthodontics and Dentofacial Orthopedics 08/2004; 126(1):82-90. · 1.38 Impact Factor
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ABSTRACT: The purpose of this study was to investigate changes in the palatal form in patients treated with and without premolar extractions. Records collected at pretreatment, at bracket removal, at the end of retention, and 5 years out of retention were examined. Stone casts were mounted on an articulator with an anatomic face-bow and a central wax record, and measurements were made with a 3-dimensional digitizer. The hypothesis that orthodontic treatment with premolar extractions changes the palatal form was verified.
American Journal of Orthodontics and Dentofacial Orthopedics 08/2004; 126(1):91-9. · 1.38 Impact Factor
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ABSTRACT: This study aimed to evaluate the clinical success of a hydrophilic polyvinyl siloxane impression material for fixed dental restorations under various clinical conditions.
A total of 1,466 preparations for fixed restorations in maxillary and mandibular anterior and posterior teeth were evaluated. The study contained inlay, onlay, crown, veneer, post, and adhesive-wing preparations and implants for gold, porcelain-fused-to-metal, and ceramic restorations. The preparation finish line relative to the crest of the marginal gingiva, type of restoration, and position of the teeth were recorded. Three categories were established to rate impression quality: perfect impressions, with an absence of any voids or bubbles and perfect reproduction of the preparation finish line, were rated Criteria I; acceptable impressions, with minimal defects (< or = 2 mm) not involving the preparation finish line, were rated Criteria II; and unacceptable impressions, with larger voids or bubbles (> 2 mm) or defects involving the preparation finish line, were rated Criteria III.
Overall, 96.86% of the final impressions were clinically acceptable, 89.43% of which were rated Criteria I and 7.43% of which were rated Criteria II. Only 3.14% of the impressions were unacceptable and rated Criteria III. A significant influence on impression quality was found when the preparation finish line was more than 2 mm subgingival (P < .004), as well as when a beveled preparation was used (P < .004). The position of the teeth (P > .404) had no significant effect.
Surface-activated polyvinyl siloxane impression material offers high predictability to avoid bubbles and voids in the final impression.
The International journal of prosthodontics 20(3):270-4. · 1.38 Impact Factor
