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At least 649 records · Page 36Linked to original sources
PubMed2003

Deciduous dentition-anchored rapid maxillary expansion in crossbite and non-crossbite mixed dentition patients: reaction of the permanent first molar.

This preliminary report describes our evaluation of the behavior of permanent maxillary first molars subsequent to rapid maxillary expansion (RME) in the mixed dentition in crossbite and non-crossbite cases; maxillary deciduous canines and second molars were used as anchorage. The RME appliance was cemented on the maxillary deciduous second molars and canines in 19 (13 females, six males) patients with unilateral or bilateral permanent molar crossbites (Group A) and in 13 (10 females, three males) patients who had no crossbites (Group B). After a mean appliance activation period of 15 days for 4-8 mm expansion, the appliance was stabilized and kept in place as retention for 5-10 months. Neither active nor passive retention was applied on first permanent molars. Impressions of dental arches were made before insertion of the appliance (T1), at stabilization (T2), and at debanding (T3). Dental measurements were registered at T1, T2, and T3. In Group A, the mean maxillary permanent intermolar width was 40.6 mm at T1, 46.0 mm at T2, and 46.3 mm at T3. In Group B, 42.4 mm at T1, 46.3 mm at T2, and 45.4 mm at T3. In all subjects, the intermolar width increased during the active phase, and in Group A the crossbite was corrected and the correction was spontaneously stable. In these patients, deciduous teeth could support the heavy forces produced by the RME appliance. The maxillary intermolar distance was spontaneously increased and then maintained with no retention in Group A. The mean spontaneous expansion of permanent maxillary molars was approximately half of the mean expansion of the screw and the anchor deciduous teeth.

Child↗
PubMed1996

An investigation of the rationality of lower third molar removal, based on USA National Institutes of Health criteria.

The appropriateness of surgical removal of lower third molars was audited in relation to 500 consecutive patients referred to hospital for third molar management during 1993/4. The National Institutes of Health (NIH) criteria were used as the validating standard. Immediately after patients had been seen for treatment planning, research workers repeated history taking and clinical examination and recorded the treatment that was planned. Appropriateness of treatment planning was then assessed. A total of 95% of patients had bilateral and 5% had unilateral lower third molars (976 teeth in all); 69% were partially erupted, 35% unerupted and 5% fully erupted. There was a weak correlation between eruption status of bilateral third molars. The most frequent reason for removal of third molars (31%) was pericoronitis, though the next most frequent reason was that the contralateral tooth had been scheduled for removal under general anaesthesia. Allowing this as a legitimate reason for surgery, of 859 teeth scheduled for removal, 59% were justified according to NIH criteria. Some 169 (34%) of patients might have avoided surgery altogether if NIH criteria had been the basis for intervention and a further 147 (30%) could have been scheduled for removal of only one lower third molar. These findings suggest that criteria for removal other than NIH criteria are being applied. Further research is necessary to identify these.

Adolescent↗
PubMed1997

Prophylactic removal of impacted third molars: an assessment of published reviews.

OBJECTIVE: To evaluate published reviews of the appropriateness of prophylactic removal of impacted third molars. DESIGN: Systematic review and critical appraisal of relevant reviews. METHODS: Computerised databases (Medline and Embase), the Index to Dental Literature, and the references of articles were searched to identify relevant reviews. MAIN OUTCOME MEASURES: Pathologies associated with impacted third molars and outcomes following surgical removal of third molars. RESULTS: Twelve published reviews were assessed. Major methodological problems in these include that authors did not describe review methods such as literature search strategy and criteria for inclusion of primary studies. Reviews with similar aims included different sets of primary studies as evidence. Details of primary studies quoted were seldom sufficient for readers to judge the reliability of the evidence. With the exception of two reviews with poorer quality, the reviews concluded that there is a lack of evidence to support the prophylactic removal of impacted third molars. Two decision analyses also concluded that, on average, patients' long-term wellbeing is maximised if extraction is confined to those impacted third molars with pathology. CONCLUSIONS: In the absence of good evidence to support prophylactic removal, there appears to be little justification for the removal of pathology-free impacted third molars.

Contraindications↗
PubMed1998

Intra-observer reliability regarding removal of asymptomatic third molars.

OBJECTIVE: To investigate reliability of practitioners' removal decisions and judgements of risk of pathology associated with asymptomatic third molars. SUBJECTS: 10 oral surgeons and 18 family dentists from South Wales with experience ranging from 5 to 28 years. METHOD: Participants were presented with periapical radiographs of 36 asymptomatic, mandibular third molars and were informed of the age and sex of the patients and the degree of eruption of the third molars. Participants were asked to assess, using visual analogue scales, the likelihood of future pathology if the third molars were left in situ and to indicate if they should be removed or not. To assess intra-observer reliability, the 36 cases were duplicated and presented to the participants on a different occasion, a month later. The same questions were asked as on the first occasion. RESULTS: Significant correlations (Pearsons correlation coefficients) were found between initial and repeat assessments of all measures but there was little agreement about the need for removal (Kappa values: 0.54 for oral surgeons and 0.41 for the family dentists). For every item studied, changes in position on the visual analogue scale of two-thirds or more of the total length occurred from the first to the second assessment. CONCLUSION: Treatment decisions about whether or not to remove asymptomatic third molars were not made on a rational basis. Since similar conclusions were recorded in a previous Swedish study, it is inferred that until further high quality evidence of disease prediction is published, decisions to remove third molars prophylactically cannot be made reliably.

Adult↗
PubMed2004

Initial intrusion of the molars in the treatment of anterior open bite malocclusions in growing patients.

The treatment of the hyperdivergent phenotype and/or anterior openbite is one of the common problems facing orthodontists. The purpose of this study is to present a new appliance (Molar Intruder) for molar intrusion and to determine its effects in the treatment of anterior openbite. The study group comprised 14 patients (eight girls and six boys), with a mean age of 10 years and 7 months. All presented anterior open bite malocclusions between the second premolars. The study was carried out on lateral head films taken before (T1) and after (T2) molar intrusion. Periapical radiographs, study models, and standard photographs of all the patients were also obtained before and after molar intrusion. The paired sample t-test was used to determine the differences between the parameters. The average treatment time with the Molar Intruder was five months. The mean intrusion of maxillary and mandibular molars was 1.86 mm and 1.04 mm, respectively. Maxillary incisors extruded 0.54 mm with a labial tipping of 1.46 degrees and overbite increased by 4.00 mm. The mandibular plane angle was decreased by 1.57 degrees, and the anterior face height was decreased by 1.86 mm on average. The mandible showed a counterclockwise rotation, the chin moved forward, and the posterior facial height/anterior facial height ratio was increased. Anterior openbites of the patients were significantly rehabilitated at the end of the intrusion period, simplifying further orthodontic treatment.

Cephalometry↗
PubMed2005

Efficiency of noncompliance simultaneous first and second upper molar distalization: a three-dimensional tooth movement analysis.

Objective of this prospective study was the three-dimensional (3D) analysis of tooth movements after the noncompliance simultaneous distalization of the first and second maxillary molars. Ten patients (five girls and five boys; mean age: 13.2 years) with bilateral Class II molar relationships were treated with a noncompliance, fixed intraoral appliance. Upper second molars had already erupted in all cases. Dental casts and lateral cephalometric radiographs were taken immediately before placement and after removal of the appliance. The casts were 3D digitized and superimposed on a predefined area in the palate. The resulting holograms, as well as the cephalometric radiographs, were digitized and analyzed by means of customized cephalometric software. The whole procedure was repeated after a two- to four-week interval to estimate the error of both methods. The cast assessment of 3D sagittal and vertical tooth movements was more reliable than the cephalometric record. The average maxillary first molar distal movement was 2.8 mm. Anchorage loss was expressed by a 1.9-mm proclination of the central incisors. A substantial variation among patients and among the right and left side in the same patient was observed. Noncompliance simultaneous distalization of the first and second maxillary molars can be an efficient treatment option for the correction of Class II molar relationship. However, anchorage loss and individual variation have to be seriously considered. Bilaterally symmetrical effectiveness should not be relied upon.

Adolescent↗
PubMed2005

The effects of first premolar extractions on third molar angulations.

The purpose of this study was to determine the relationship between the inclinations of second and third molars during a two- to 2.5-year period in patients treated orthodontically both with and without premolar extractions. Records of 37 first premolar extraction patients and 33 nonextraction patients were examined. The pretreatment and posttreatment panoramic radiographs were analyzed. The angles were measured between the long axis of the third molar and the occlusal plane and between the long axis of the third molar and the long axis of the second molar. Changes in third molar angulations from pretreatment to posttreatment for two groups were compared by Mann-Whitney U-test. Statistical analysis revealed that mandibular third molars showed an improvement in angulation relative to the occlusal plane in the first premolar extraction group.

Adolescent↗
PubMed2002

C-shaped root canal configuration in maxillary first molars.

AIM: This clinical report presents the endodontic treatment of two maxillary first molars and the anatomical study of two additional maxillary first molars with a C-shaped distally located root canal system. This configuration is not a common finding. SUMMARY: According to the endodontic literature, the C-shaped root canal is most frequently seen in the mandibular second molar. The occurrence of C-shapes in maxillary first molars, however, has only been described in a limited number of case reports. We observed this configuration in two out of 2175 root-filled maxillary first molars treated at the Department of Endodontology, Ghent University Hospital, during the last 10 years. In order to study and visualize this particular aberration, cross-sections in two additional two-rooted maxillary first molars were made. From these cross sections it can be concluded that the C-shaped canal configuration is the result of a fusion of the distobuccal and the palatal roots.

Adolescent↗
PubMed2001

Root resorption in retained deciduous canine and molar teeth without permanent successors in patients with severe hypodontia.

AIMS: The ability to predict the morbidity of retained deciduous teeth with no permanent successors, a characteristic of hypodontia, would be of considerable value in treatment planning, but is hampered by lack of data. METHODS: This problem was studied using 356 orthopantomogram radiographs (OPGs) from the records of 249 patients who had attended a specialist hypodontia clinic, and had retained deciduous teeth with no permanent successors. Due to their clinical importance, canine and molar teeth were chosen for examination. Resorption was assessed subjectively by three experienced clinicians. RESULTS: Un-weighted Kappa values for reproducibility were > 0.8, and for interobserver error 0.60-0.83. Gender related differences were minimal. Regardless of gender or radiographic age, the lower canines appear to show the least amount of resorption and the upper first molars the most. The upper and lower second molars have particularly unpredictable life spans. Whilst the lower first molars have a predictable life span that is poor, the life span for the upper first molars is slightly worse. CONCLUSIONS: Lower canines have a predictable life span that appears to be good, as do upper canines, but of lesser duration than lower canines. Molars have poorer and less predictable life spans.

Adolescent↗
PubMed1998

Difference in the mechanism of balancing-side disclusion between 1st and 2nd molars.

This study investigates the cusp angle and movement variables related to balancing-side disclusion and compares the characteristics between the 1st and 2nd molar regions. Fifty-six normal young adults were divided into two groups according to balancing-side contact: a disclusion group consisting of 40 subjects (80 excursions), and a non-disclusion group consisting of 16 subjects (20 excursions). Lateral excursions were measured in six-degrees of freedom, and the inclinations of the frontal paths were calculated on the working-side canine, balancing-side 1st and 2nd molars and balancing-side condylar point. The cusp angle was measured using a three-dimensional digitizer. While there were no differences between disclusion and non-disclusion groups in the inclination of the balancing-side condylar path, significant differences were found in the cusp angle and the inclination of the working-side canine path. In the non-disclusion group, the cusp angle of the 2nd molar was markedly greater than that of the 1st molar. It was concluded that the inclination of the anterior guidance and the cusp angle of related teeth have a great effect on the occurrence of balancing-side disclusion and that the mechanism of high frequent balancing-side contacts at the 2nd molar was characterized by its greater cusp angle compared to the 1st molar.

Adult↗
PubMed2001

Complications of the mandibular sagittal split ramus osteotomy associated with the presence or absence of third molars.

PURPOSE: This study compared the number of unfavorable fractures after sagittal split osteotomies (SSOs) of the mandible when third molars were present or absent. PATIENTS AND METHODS: The treatment records of 262 patients (500 SSOs) were retrospectively evaluated. Group 1 consisted of 250 SSOs and concomitant removal of impacted mandibular third molars and group 2 consisted of 250 SSOs with absence of third molars. A modified SSO technique with inferior border cuts was used on all patients, and the third molars, when present, were removed after separation of the proximal and distal segments. Rigid fixation was applied using bicortical bone screws. Bone plates with monocortical screws were additionally used to secure the free bony segments of the proximal segment in cases with unfavorable fracture. RESULTS: There were 11 (2.2%) unfavorable fractures in 500 SSO procedures. The incidence of unfavorable splits was 3.2% in group 1 and 1.2 % in group 2. In group 1, all fractures occurred in teenagers, with 7 of 8 fractures extending through the extraction socket in the distal segment. Six of the 8 fractures were associated with completely impacted third molars, and 2 involved partially impacted teeth. All 3 fractures in group 2 occurred in the proximal segment. No significant difference was seen in the amount of relapse in patients with unfavorable or favorable splits. CONCLUSIONS: The occurrence of unfavorable splits is uncommon when using a modification of the SSO that includes an inferior border osteotomy. Although more unfavorable fractures occurred in teenage patients with third molars, this had no impact on the stability of the final result.

Adolescent↗
PubMed2001

The role of third molar surgery in the exacerbation of eating disorders.

PURPOSE: Eating disorders are a major public health problem. This study was undertaken to investigate the role of dental surgery in the etiology and clinical course of these serious and occasionally life-threatening disorders. METHODS: Three questions concerning dental therapy were included in a pretreatment assessment of 97 consecutive patients entering an eating disorder therapy program during a 22-month period. These questions were designed to determine the influence of dental surgery, including frequency and severity, on eating disorders. RESULTS: All 97 patients, of which 96 were female, complied with the questionnaire. Seventy-five of 97 were 25 years or younger, and 53 of 97 were diagnosed as having anorexia nervosa. Sixteen patients (16.5%) reported having had orthodontic therapy, and 21 (21.6%) had undergone third molar surgery. Nine patients (9.3%) (1 orthodontic, 8 third molar surgery) indicated that dental procedures had caused exacerbation or relapse of their eating disorders; 8 of 21 (38%) who had undergone third molar surgery were positive respondents. None of the patients linked dental care to the initial onset of their eating disorders. CONCLUSIONS: These data reveal that dental procedures, specifically third molar surgery, can significantly alter the course of eating disorders, causing exacerbation or relapse. No patient indicated that dental therapy was the primary cause of these multifactorial psychonutritional disorders. A history of eating disorder should alert the practitioner to the risks of performing third molar surgery without a medical or psychotherapy consultation unless there is documentation of remission. Delay of surgical intervention is recommended if third molars are asymptomatic. If surgery is necessary, the surgeon and other members of the psychotherapy team should establish clear guidelines regarding behavior and postoperative nutrition and should monitor the patient's nutritional status.

Adolescent↗
PubMed1999

Mandibular third molars: oral surgeons' assessment of the indications for removal.

The aim was to examine oral surgeons' assessment of the indications for removal of mandibular third molars. Questionnaires were distributed to seven oral and maxillofacial surgery clinics. The oral surgeons were asked to record whether or not there was associated disease. Three other factors were recorded: patient's age, and angular position and extent of eruption of the molars. The strength of the indication for removal was rated on a visual analogue scale (VAS) where 0= weakest and 100= strongest indication for removal. The results were based on data from 666 molars: 118 (18%) had no disease, 465 (70%) had one associated disease, 77 (11%) had two and 6 (1%) had three. The indication for removal as expressed by the mean VAS for molars with no disease was assessed to be weaker (P<0.05) than that for molars with one, two, or three diseases. The only factor that influenced the indication for removal in molars with no disease was the patient's age.

Adolescent↗
PubMed2002

Impacted third molars and risk of angle fracture.

The purpose of this study was to assess the influence of the presence, position, and severity of impaction of the mandibular third molars, on the incidence of mandibular angle fractures. A retrospective cohort study was designed for patients presenting to the Division of Oral and Maxillofacial Surgery, Toronto General Hospital (Toronto, Canada), for treatment of mandibular fractures from January 1995 to June 2000. The independent variables in this study were the presence, position and severity of impaction of third molars. The outcome variable was the incidence of mandibular angle fractures. Hospital charts and panoramic radiographs were used to determine and classify these variables. The demographic data included age, sex, mechanism of injury and number of mandibular fractures. The study sample comprised 413 mandibular fractures in 214 patients. The incidence of angle fractures was found to be significantly higher in the male population and was most commonly seen in the third decade of life. Assault remained the most significant aetiological factor. Patients with third molars had thrice the increased risk of angle fractures when compared to patients without (P<0.001). Impaction of third molars significantly increased the incidence of angle fractures (P<0.001). The severity and angulation of third molar impactions were not significantly associated with angle fractures. This study provides evidence that patients with retained impacted third molars are significantly more susceptible to angle fracture than those without. The risk for angle fracture, however, does not seem to be influenced by the severity of impaction.

Adult↗
PubMed2000

Tooth anomalies associated with failure of eruption of first and second permanent molars.

The occurrence of tooth anomalies in association with failure of the first and second molars to erupt was assessed in a sample of 1520 nonsyndromic subjects with uncrowded dental arches (mean age, 14 years 4 months) and compared with the prevalence rate calculated in a matched control group of 1000 subjects. The tooth anomalies examined included infraocclusion of deciduous molars, palatal displacement of maxillary canines, rotation of maxillary lateral incisors, aplasia of second premolars, and small size of maxillary lateral incisors. Associations among arrested eruption of first and second permanent molars and anomalies in tooth eruption and position (infraoccluded deciduous molars, palatally displaced canines, rotated maxillary lateral incisors) were highly significant (P <. 001). No significant association was found among the occurrence of molar eruption disturbances, aplasia of premolars, and small-sized laterals. These findings point to a common biologic cause for the appearance of failure of eruption of molar teeth and other disturbances in tooth eruption and position, most likely under genetic influence.

Adolescent↗
PubMed2001

Presence of third molar germs in orthodontic patients in Japan.

The purpose of this investigation was to evaluate the existence of third molar germs in orthodontic patients in Japan and to examine the relationship between the existence of third molars and sagittal maxillomandibular jaw relationships. The subjects comprised 306 patients from the orthodontic clinic of Hokkaido University Dental Hospital who were younger than 15 years. The subjects were divided into 2 groups: 1 group included 144 patients who were born between 1966 and 1969 (60s group), and the other group included 162 patients who were born between 1980 and 1987 (80s group). Assessments were made from panoramic radiographs and lateral cephalograms. The following results were obtained: (1) all 4 third molar germs were present in 77% of subjects, (2) mandibular third molars were present significantly more often than maxillary third molars, and (3) the percentage of skeletal Class III subjects who had all 4 third molars was lower than that of skeletal Class II subjects. The chi(2) test was used to determine statistical significance in differences.

Adolescent↗
PubMed2002

Transition of molar relationships in different skeletal growth patterns.

This study investigated maxillary and mandibular growth differences and their effect on the changes in molar relationships from early transitional dentition to adult permanent dentition. Various landmarks were identified and measurements made on the longitudinal cephalometric radiographs of 40 people. The subjects were classified into 3 groups based on the amount of sagittal skeletal growth difference between the jaws. In group A, the mandible grew more than did the maxilla; in Group B, growth was about the same; and in group C, the maxilla grew more than did the mandible. The results revealed that skeletal growth differences between the jaws significantly influenced the changes in molar relationship during the transitional dentition, not only by translating basal bones but also by altering the amount of physiologic mesial shift in the dentition. However, the skeletal growth difference during the permanent dentition did not influence the changes in molar relationship. The sagittal growth difference between the jaws was largely absorbed by a dentoalveolar compensation. Tooth movement showed different characteristic features depending on the amount of the skeletal growth difference: (1) If the mandible grew more than did the maxilla, the growth difference was mostly absorbed by mesial displacement of the maxillary first molars and counterclockwise rotation of the occlusal plane. Anterior occlusion was adjusted by mesial displacement and labial inclination of the maxillary incisors and lingual inclination of the mandibular incisors. (2) If the maxilla grew more than did the mandible, the growth difference was mainly absorbed by mesial displacement of the mandibular molars. Then the maxillary molars showed minimal mesial displacement. The occlusal plane also showed minimal rotational change. Anterior occlusion was adjusted by lingual tipping of the maxillary incisors and mesial displacement and labial tipping of the mandibular incisors.

Adaptation, Physiological↗
PubMed2002

A 3-dimensional analysis of molar movement during headgear treatment.

Superimposition of serial cephalograms provides a limited description of tooth movement that could be complemented by data obtained from serial dental casts. The aim of this study was to develop a mathematical method for superimposing 3-dimensional data obtained from selected landmarks on longitudinally collected dental casts to describe maxillary first molar movement during headgear treatment. The material consisted of dental casts taken bimonthly from 36 children whose Class II Division 1 malocclusion was treated with straight-pull headgear during a 24-month period. Control data were collected from initial and final models of 38 subjects with a similar malocclusion who were not treated during a 24-month observation period. Spatial data from each subject's initial model were oriented similarly in an anatomically derived coordinate system, and a best-fit superimposition of palatal rugae landmarks from subsequent models allowed the measurement of molar movement. On average, headgear treatment resulted in distal movement of the molars, and the fitted net difference between treated and control subjects was 3.00 mm (SE, 0.37 mm; P < .001). Also, the headgear caused significantly more molar extrusion (0.56 mm; SE, 0.20 mm; P < .006) and buccal expansion (0.58 mm; SE, 0.17 mm; P < .001) on average than in the control group. Poor reliability of the method for measuring molar rotations indicated that they could not be determined accurately. Longitudinal description of molar movement for each subject revealed great individual variability in the amount and pattern of tooth movement. Several reasons could account for the wide range of individual variation and warrant exploration.

Case-Control Studies↗