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At least 595 records · Page 33Linked to original sources
PubMed1976

The maintenance system and occlusal dynamics.

We have discussed the maintenance system and its relationship to occlusal dynamics and occlusion function. The premise has been set forth that to avoid untoward sequelae post-orthodontically in the areas of relapse of tooth positions, occlusal wear, periodontal disease, and temporomandibular pain-dysfunction, it is best to have an occlusion free from centric and excursive interferences. The practical approach to the desired goal for the orthodontist lies in an understanding and familiarity of occlusal dynamics that allows him to look at detailing of tooth positions with insight into their ramifications from a functional standpoint. The insight can only be gained by hard work and self-discipline in the study of occlusion. A knowledge of these concepts will alert the orthodontist ot the true severity of the cases he is treating, allow him to position teeth so as not to create problems and , lastly, to be able to competently handle those cases that do develop posttreatment problems.

Bruxism↗
PubMed2000

[Developmental tendencies of the sagittal tooth axis between 10-13 years of age and the end of life; impact on retention?].

In this study, 854 lateral cephalograms of normal toothed subjects from 10 to 87 years old who had no orthodontic treatment are analyzed. The posterior angles established by molars and sagitally examined maxillo-mandibular incisor-canine groups during occlusion are measured with age. These modifications are quantified in a general manner and then depending on facial typology.

Adolescent↗
PubMed2000

Combined periodontal-prosthodontic treatment of early-onset periodontitis--an alternative to implant therapy.

A variety of treatment systems should be available for patients whose dentitions are seriously compromised so that they may select customized treatment modalities that satisfactorily restore occlusal function, consider systemic conditions, and lessen the surgical and financial burdens. These requirements become more demanding when clinicians are faced with advanced cases of rapidly progressive periodontitis. Therefore, it is critical to establish sophisticated multidisciplinary treatment modalities for the successful management of these compromised patients. Obviously, because of various limitations, implant therapy cannot be the only solution. This article reports on the successful long-term management of seriously compromised early-onset periodontitis by a combined periodontal-prosthetic treatment as an alternative to implant therapy.

Adult↗
PubMedDate not supplied

Vertical position, rotation, and tipping of molars without antagonists.

PURPOSE: There has been a general belief that permanent teeth without antagonists overerupt, creating, after some time, considerable clinical problems. However, very few studies in the literature support this statement. The purpose of this investigation was to examine the position of molars that had been unopposed for a long period and to test the hypothesis that overeruption does affect every tooth without an antagonist. MATERIALS AND METHODS: Fifty-three individuals were examined clinically, and dental casts were taken to evaluate the position of unopposed molars. There were 84 molars (61 in the maxilla and 23 in the mandible) with a documented period of at least 10 years without antagonists. Among these teeth, 25 molars had neither an antagonist nor a mesially adjacent tooth. A qualitative method was used to evaluate the position of the molars in the vertical direction: (1) teeth with no sign of overeruption, (2) teeth with slight overeruption (< 2 mm), and (3) teeth with moderate to severe overeruption (> or = 2 mm). RESULTS: Of the 84 molars examined, 15 teeth (18%) revealed no signs of overeruption, 49 teeth (58%) displayed overeruption of less than 2 mm, and 20 teeth (24%) showed moderate to severe overeruption. Individuals with molars that had lost their antagonists in adult age had a lower risk for overeruption than the other subjects examined. The existence of adjacent teeth was important for the position of the unopposed molar in a mesiodistal or buccolingual direction. Molar rotation was more frequent in the maxilla, whereas tipping was more common in the mandible. CONCLUSION: It is concluded that not all molars without antagonists overerupt, not even in a long-term perspective.

Adult↗
PubMed2000

A cephalometric study of the effect of extraction of lower first permanent molars.

The sample consisted of 28 patients (16 female: 12 male) from the records of the Orthodontic Department for whom the extraction of both lower first permanent molars was considered due to caries. The age ranged from 8-14 years (mean age 12.4). A cephalometric radiograph was taken prior to the extraction and after a mean of 18 months. No other treatment was done during the observation period. The radiographs were traced arid digitized using the GeLa program. A total of 16 points were digitized yielding 19 measurements (7 angular and 12 linear). The data were analyzed using 't' test and Pearson Correlation Coefficients in SPSS PC and compared to a control group matched for age and sex. Results showed that on average, the lower second molar moved forwards 5.9 mm. On average there was no change in angulation of the incisors to the bases. There was no significant change in the vertical relations of the jaws save that caused by normal growth and development. A significant correlation was found between the change in overbite and original overbite (r = -0.55, P < 0.01), the change in Li/A-Pog (r = 0.41, P < 0.05) and the change in facial proportions (r = -0.59, P < 0.001). The change in overjet was correlated with the change in Li/A-Pog (r = 0.58, P < 0.001) and change in Li/mand (r = -0.55, P < 0.01). The extraction of the lower first molars results in deepening of the overbite on average, but has no effect on the anterior facial height or any other vertical relationship. However, the increase in overbite is associated with lingual positioning of the lower incisor and the change in facial proportions. The change in overjet is related to lingual positioning and retroclination of the lower incisors.

Adolescent↗
PubMed2000

[Long-term stability of orthodontic treatment].

Aim of this study was to assess long-term stability of orthodontic treatment in a sample of 1016 patients until 10 years postretention. Treatment outcome was measured with the PAR-index at 6 different stages. The mean age of the patients was 12.0 +/- 3.1 year at the start of treatment to 26.3 +/- 2.9 year 10 years postretention. The results show that 67% of the orthodontic treatment result, as measured with the PAR-index, was maintained 10 years postretention. The PAR-scores for the midline and the open bite remained about the same over the years. However, the scores for the lateral occlusion, overjet, reversed overjet, overbite, and contact point displacement of the upper and lower front teeth increased gradually over time. Nearly 50% of the total relapse took place the first two years after retention. The largest change was found for the position of the lower incisors. Ten years postretention their position was even worse than at the start of treatment.

Adolescent↗
PubMed2002

Effect of serial extraction alone on crowding: relationship between closure of residual extraction space and changes in dentition.

Mandibular dentitions from 33 subjects who had undergone serial extraction without appliances were analyzed at three stages: before extraction of deciduous canines (T1), after extraction of first premolars (T2), and at the end of the observation (T3). It was suggest that the mesial movement or tipping of the second premolars was associated with most of the space closure from T2 to T3, although the distal movement or tipping of canines might also contribute space closure.

Analysis of Variance↗
PubMed2002

[Repair and revision 8. Relapse of lower incisors: retreatment?].

Research into the long-term stability of orthodontic treatment at the University of Nijmegen (the Netherlands) until 10 years after retention has shown that nearly 50% of the total relapse takes place the first two years after retention. After that period certain stability is reached except for the lower front teeth. Ten years after the retention phase their position is even worse than at the start of treatment. The changes in lower front teeth alignment are the result of relapse, but also of normal physiological changes during ageing of the dentition. Therefore it is questionable whether late mandibular incisor irregularity should be (re)treated. Relapse of mandibular incisor alignment shortly after debonding can be restored by tightly tying the rotated incisor(s) to the C-C bar with a steel ligature, by using a spring-retainer or by rebonding of brackets to the lower front teeth. After correction of the incisor position the C-C bar should be bonded to all lower front teeth. (Re)treatment of mandibular incisor irregularity at an older age asks for more complicated treatment mechanics.

Humans↗
PubMed2002

[The dry skull model in orthodontics].

Orthodontic therapy aims to displace teeth by means of orthodontic appliances. Forces, applied on the teeth, induce remodeling of the alveolar process in upper and lower jaw resulting in a new position of the teeth into both jaws. In this publication an attempt has been made to test a model (dry skull model) which could provide a better understanding of the effect of force application on tooth and bone displacement. Initial tooth displacement (microscopical), right after force application, could give an indication for the longitudinal tooth displacement to be expected. Variables as the point of force application, the amount and direction of the force and the localisation of the centre of resistance are determining factors for the final tooth displacement. This study attempts to forecast the longitudinal tooth displacement by evaluating the initial displacement on the dry skull. Initial tooth displacement has been measured by means of laser measuring techniques (holography, speckle interferometry and laser reflection technique). These techniques are non-invasive (non-destructive testing) and permit the measurement of small tooth and bone displacements varying between 0.5 and 15 microns. According to the results of the animal studies, it became obvious that initial tooth and bone displacements are indicative for the longitudinal effect of the same sort of force application on a short time basis (5 to 8 weeks). The final conclusion is that initial tooth displacement measured on a dry skull has a predictive value for the longitudinal effect of orthodontic force application. Moreover, the creation of a finite element model looks very promising in this respect. More research is needed to test the finite element model further and to make it useful for testing the effect of force application on skull and tooth structures of a patient.

Animals↗
PubMedDate not supplied

Clinical performance and survival of space maintainers: evaluation over a period of 5 years.

The study investigated the clinical performance of 387 space maintainers fitted in 358 patients aged from 3 to 9 years in the Department of Pediatric Dentistry at the Faculty of Dentistry-University of Jordan from 1996 to 2000. Failure occurred in 119 appliances (30.7%), of which 49.6% were due to solder breakage, 32.8% from cement loss, 11% from soft tissue lesions, 4.2% from eruption interference, and 2.5% were completely lost. By using the Kaplan-Meier method, the estimated median survival time for space maintainers was 18 months. Lingual arches had the lowest median survival time of 14 months. Bands and loops, Nance appliances, and removable partial dentures had similar probability of survival. Fixed bilateral mandibular appliances recorded lower survival time than fixed bilateral maxillary appliances. Gender, age, type of dentition, fixed vs. removable, year of placement of the appliance and number of space maintainers fitted simultaneously in the same patient had no significant effect on survival of the appliances.

Chi-Square Distribution↗
PubMed1975

[The behavior of the lower front teeth after systematic extraction of the upper premolars].

Narrowly spaced frontal teeth in the lower jaw have been the object of repeated discussions in the orthodontic literature. There are a number of factors which either directly or indirectly cause the space between frontal teeth in the lower jaw to become narrower and narrower in the course of life. The purpose of the present work was to find out whether orthodontically indicated extraction of premolare in the upper jaw may, in the case of distal occlusion, result in the space between front teeth in the lower jaw becoming narrower and narrower.

Bicuspid↗
PubMed2003

[Establishment of normal value of posterior arch length of adolescence in Chengdu].

OBJECTIVE: To investigate the development of third molar embryo and establish the normal value of posterior arch length of adolescence in Chengdu. METHODS: The samples consisted of 40 males and 41 females with Class 1 dentitions, normal second molar occlusion, no history of orthodontic treatment, and good facial balance. Cephalometry and statistic analysis were conducted for all the subject. RESULTS: The normal value of posterior arch length of maxilla in male was(16.52 +/- 2.35) mm and in female was(16.42 +/- 2.55) mm. The normal length of mandible was(13.00 +/- 2.44) mm in male and(12.43 +/- 2.18) mm in female. But statistic analysis showed no gender difference. Most of the third molar embryo had been formed and their tooth crowns had been calcified, the occurrence ratio was 84.0% in maxilla and 85.2% in mandible. Most of them located in the middle and inclined mesially. CONCLUSION: The data obtained in this study will be valuable for our clinical practice and be helpful for the study concerning dento-facial growth and development.

Adolescent↗