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At least 451 records · Page 25Linked to original sources
PubMed2002

Age as a factor in the complication rate after removal of unerupted/impacted third molars at the time of mandibular sagittal split osteotomy.

PURPOSE: This study was designed to investigate the effect that the presence of an unerupted third molar has on the mandibular sagittal split osteotomy (SSO). PATIENTS AND METHODS: One operator performed 139 SSOs (70 right side and 69 left side) in 70 patients during a period of 6 months. Data related to gender, age, presence or absence of unerupted third molar teeth, split difficulty during SSO, fracture complications of the segment, neurovascular bundle involvement at surgery, removal of unerupted third molar teeth, and the postoperative recovery of nerve function were recorded. RESULTS: The SSOs evaluated as technically difficult were significantly more prevalent in mandibles with unerupted third molar teeth. All fractures (4) occurred in the younger age group (<20 years) with unerupted third molars present at the time of surgery. Although inferior alveolar nerve recovery was slower in the patients in whom the unerupted third molar teeth were present at the time of surgery due to increased frequency of neurovascular bundle manipulation, the recovery rates at 1 year were equal. CONCLUSIONS: The presence of unerupted third molar teeth increases the degree of difficulty of the SSO. Fracture of proximal and/or distal segments during SSO tend to occur more frequently in the younger age group (<20 years) with an unerupted third molar present.

Adolescent↗
PubMed2000

An investigation into the relationship between mandibular third molars and angle fractures in Nigerians.

We examined the relationship between the presence or absence of mandibular third molars and angle fractures in Nigerians between January 1976 and July 1997. Information was obtained from patients' case records and radiographs.A total of 490 patients were seen during the study period, 408 of whom (83%) had their third molars present, and 76 of whom had angle fractures. Road traffic accidents (n =304, 62%) were the main cause of the fractures. Of these, 44 (14%) had angle fractures compared with 14/75 (19%) patients in whom the mechanism of injury was a fight or assault.Sixty-five of the 408 patients whose third molars were present (16%) had angle fractures, as did 11/82 (13%) who did not have third molars (p =0.57). Of the 77 patients whose lower third molars were not erupted, 24 (31%) had angle fractures compared with 52/331 (16%) in whom the lower third molars were erupted (p =0.002). These findings suggest that angle fractures are uncommon in this population because of their particular mechanism of injury. In addition, the presence of a lower third molar does not necessarily predispose to fractures of the angle of the mandible. However, angle fractures are more likely to occur in people with unerupted lower third molars than in those in whom they have erupted.

Adult↗
PubMed2003

The transfer of occlusal forces through the maxillary molars: a finite element study.

The morphology of the skeleton is known to reflect functional demand. A change in the intramaxillary position of molars can be expected to influence the transfer of occlusal forces to the facial skeleton. A finite element analysis allows us to simulate the displacement of a molar in relation to the well-defined morphology of the maxilla. Three 3-dimensional unilateral models of a maxilla from a skull with skeletal Class I and neutral molar relationships were produced based on CT-scan data. The maxillary first molar was localized so that the contour of the mesial root continued into the infrazygomatic crest. When the molar was loaded with occlusal forces, the stresses were transferred predominantly through the infrazygomatic crest. This changed when mesial and distal displacements of the molars were simulated. In the model with mesial molar displacement, a larger part of the bite forces were transferred through the anterior part of the maxilla, resulting in the buccal bone being loaded in compression. In the model with distal molar displacement, the posterior part of the maxilla was deformed through compression; this resulted in higher compensatory tensile stresses in the anterior part of the maxilla and at the zygomatic arch. This distribution of the occlusal forces might contribute to the posterior rotation often described as the orthopedic effect of extraoral traction.

Alveolar Process↗
PubMedDate not supplied

The third permanent molar eruption in Kenyan Africans and Asians.

Data on third permanent molar eruption was obtained from a cross-sectional study of 1343 African and 1092 Asian students aged 13-23 years attending various schools in Nairobi and the University of Nairobi, Kenya. Africans are significantly ahead of the Asians in third molar emergence. As seen from the median age of eruption, in Africans mandibular molars emerge at 17.6-18.3 years followed by the maxillary at 18.5-18.9 years, while in the Asians mandibular molars emerge at 19.9-20.3 years and maxillary at 20.7-21.0 years. African females appear to be earlier than the males in median age of eruption by 0.3-0.4 years, while the Asian females tend to be later than the males by about 0.3 years, but these differences are not significant. Third molar emergence starts earlier in Africans at 13 years of age, and by 18.5 years 50% of Africans have all four molars present. In the Asians, third molar emergence begins at about 15 years and by 21.5 years 50% have all four molars present.

Adolescent↗
PubMed1996

The effect of a transpalatal arch for the correction of first molar rotation.

The effects of a transpalatal arch for the symmetrical derotation of rotated first molars were evaluated in 50 children, 8-13 years of age. The positions of the molars were compared with those in 34 individuals, aged 12-18 years, with normal occlusion. Prefabricated (GAC) stainless steel arches were used for 60-198 days (median time 122 days). The effect was recorded with a measuring microscope on dental casts from before and after the treatment. Molar positions were determined from the tips of the four cusps of the tooth in relation to a coordinate system based on palatal reference points. The centre of rotation of the molars during derotation were calculated from the movement of their cusps. Before derotation the first molars were significantly mesiopalatally rotated compared with the normal occlusion group. The derotation overcompensated the initial rotation. In about two-thirds of the cases the mesiobuccal cusp of the molar moved distally during the derotation. In the remaining cases it moved mesially or remained unchanged. The median distal movement was 0.3 mm on the right and 0.5 mm on the left side. Because many molars moved mesially, on average there was no gain in space in the dental arch from the derotation. The location of the centre of derotation varied widely but it was on average located midway between the distobuccal and distopalatal cusps. In most cases the derotation resulted in a small, unintended, expansion. The study showed that mesiopalatally rotated first molars can effectively be derotated with a transpalatal arch. The effect on the mesiodistal position of the mesiobuccal cusp, and particularly with regard to space gain, is, however, unpredictable.

Adolescent↗
PubMed2000

Persistence of deciduous molars in subjects with agenesis of the second premolars.

The purpose of the present study was to investigate persistent primary second molars in a group of young people in their late twenties with agenesis of one or two second premolars. In 1982-83 it was decided, in connection with the orthodontic evaluation of 25 patients, to allow 35 primary molars (one or two in each patient) to remain in situ. All patients had mixed dentitions and agenesis of one or two premolars. The primary teeth were generally in good condition, although root resorption and infra-occlusion (compensated by occlusal composite onlays) occurred. In 1997, 18 of the 25 patients with a total of 26 retained primary molars were reexamined, comprising a clinical examination for exfoliation, extraction, loosening, and ankylosis, and a radiographic examination for root resorption, tooth morphology (crown and root), and alveolar bone contour. The examination showed that the degree of root resorption was unaltered in 20 of the 26 primary molars. In the permanent dentitions, where these primary molars persisted, there were no morphological deviations. Three of the six remaining primary molars had been extracted and three showed extensive resorption. In three of the 26 primary molars the infra-occlusion had worsened. The present study shows that persistence of primary second molars in subjects with agenesis of one or two premolars, and normal morphology of the permanent dentition can be an acceptable, semi-permanent solution for the patient. Whether this could also be an acceptable long-term solution will be shown by follow-up studies.

Adult↗
PubMed2005

Association between ectopic eruption of maxillary canines and first molars.

The purpose of this study was to elucidate a possible association between ectopic first molar eruption causing root resorption on the distal root of the primary maxillary second molar, and ectopic canine eruption causing root resorption on the permanent maxillary incisors. The subjects consisted of 30 patients, 22 females and eight males in the age range 8.3-15.0 years in whom root resorption of the permanent maxillary lateral and/or central incisor caused by the erupting permanent canine was diagnosed, and clinical and/or radiographic information concerning maxillary first molar eruption existed. It was found that of the 30 patients, seven (23.3 per cent) also had pathological root resorption of the second primary molar caused by ectopic molar eruption. It is suggested that patients with ectopic maxillary first molar eruption leading to pathological root resorption of the maxillary second primary molar are followed closely during the period of premolar and canine eruption, as the ectopic first molar could be an early warning of an increased risk of ectopic canine eruption leading to root resorption of the maxillary permanent incisors.

Adolescent↗
PubMed2000

Root canal morphology of human maxillary and mandibular third molars.

The anatomy of third molars has been described as unpredictable. However restorative, prosthetic, and orthodontic considerations often require endodontic treatment of third molars in order for them to be retained as functional components of the dental arch. The purpose of this study was to investigate and characterize the anatomy of maxillary and mandibular third molars. One hundred fifty maxillary and 150 mandibular extracted third molars were vacuum-injected with dye, decalcified, and made transparent. The anatomy of the root canal system was then recorded. Seventeen percent of mandibular molars had one root (40% of which contained two canals), 77% had two roots, 5% had three roots, and 1% had four roots. Teeth with two roots exhibited highly variable canal morphology, containing from one to six canals, including 2.2% that were "C-shaped." Fifteen percent of maxillary molars had one root, 32% had two roots, 45% had three roots, and 7% had four roots. Teeth with one root demonstrated the most unusual morphology, with the number of canals varying from one to six. An in vivo study of the canal morphology of treated third molars is suggested to provide the practitioner with an understanding of the clinical implications of third molar root anatomy.

Coloring Agents↗
PubMed1982

Mesial migration and lower third molar tilt.

The angulation of lower third molars is compared in two groups of radiographs of children aged 10.1--13.0 years, one group showing lower second deciduous molars present, the other showing mesial migration of lower first permanent molars and impaction of second premolars following early extraction of lower second deciduous molars. The lower third molar crypts are significantly less tilted in the group where deciduous molars had been removed, the difference between the means of the two groups being 12.5 degrees (p less than 0.001). The findings are discussed in relation to the hypothesis that early mesial migration improves the orientation of third molar crypts by enabling them to develop further forward. There is some evidence that the mean angle of tilt may be reduced by about 20 degrees when mesial migration occurs before third molar crypts begin to form.

Adolescent↗
PubMed1999

Uprighting molars without extrusion.

BACKGROUND: Orthodontic molar uprighting often results in extrusion of the molar, which is not always beneficial. The authors present a strategy for accomplishing molar uprighting without extrusion. DESCRIPTION OF THE PROCEDURE: The authors review and compare the benefits of molar uprighting with and without extrusion. The helical uprighting spring is probably the most popular appliance used for molar uprighting. It exerts an extrusive force on the molar during uprighting. The authors explain why this appliance produces an extrusive force and present a strategy to modify the appliance so that it can be used to upright without extrusion. CLINICAL IMPLICATIONS: The information presented in this article should help the dental practitioner select a suitable appliance, understand how it works and use it appropriately so that molar uprighting can be achieved without extrusion of the molar.

Dental Stress Analysis↗
PubMed2001

Third-molar removal patterns in an insured population.

BACKGROUND: The authors examined third-molar removal patterns in an insured population to see how these patterns compare with recommendations in the literature. METHODS: The source of treatment data was insurance claims for services rendered from July 1991 through December 1999; it included approximately 100 million dental procedures provided to about 7.4 million patients from all 50 states. The insured were public and private employees or retirees and their dependents. RESULTS: The authors found that third molars were the most commonly extracted permanent teeth, and they most often were removed from adolescents. Friday was the day of the week on which most extractions occurred, and the favored month was August, followed by July, December and June. Another important pattern revealed by the authors' analysis was that there was substantial variation among dental practices in whether patients had third molars removed and in the timing of the removal. They found that adolescent patients in some dental practices rarely were referred for third-molar removal, while in other practices, most or all had third molars removed. CONCLUSIONS: Third-molar removal patterns suggest that many third molars are not removed in response to acute pathology, and the observed variation in the likelihood and timing of these extractions reflects the lack of consensus on this topic in the dental literature. CLINICAL IMPLICATIONS: The apparent lack of consensus on third-molar removal should be resolved for the profession to maintain the confidence of the public that the recommended care is based on sound evidence.

Adolescent↗
PubMed2003

Influence of angular position and degree of impaction of third molars on development of symptoms: long-term follow-up under good oral hygiene conditions.

To determine the risk of developing symptoms due to the presence of maxillary and mandibular third molars, we analyzed a reliable population sample by age, and according to third-molar position and impaction level using long-term follow-up data under conditions of good oral hygiene. Of 308 graduates from our dental school, a total of 776 third molars were followed up for periods of 11 to 27 years by means of intraoral radiographs. The development of symptoms, the participant's age, and third-molar angular position and degree of impaction were investigated. For both maxillary and mandibular third molars, the risk of developing a symptom correlated neither with angular position nor with impaction level. The first symptom associated with a third molar developed most frequently in their 20's for both maxilla (16.2%) and mandible (17.5%), with the next highest frequency being in their 30's (12.6%, maxilla; 13.0%, mandible). The status of third molars shows no relation to the subsequent development of symptoms if good oral hygiene is maintained. The low rates of symptom-development do not support removal of asymptomatic third molars.

Adult↗
PubMed1980

Furcation involvement in maxillary and mandibular molars.

This is a sequel to a previous study that showed that many molars with furcation involvement (F.I.) can survive in a state of health and can function efficiently and without pain for many years. This finding is at variance with the views of others who believe that the prognosis for teeth with F.I. is unfavorable. The conclusions of the present study are: (1) F.I. of molars was a common finding; it occurred much more frequently than anticipated. (2) F.I. occurred three times more frequently among maxillary molars than among mandibular molars. (3) Many molars with F.I. functioned well from 5 to 24 years. (4) Based on these findings, it is suggested that two aspects of molars with F.I. be reevaluated, i.e. their prognosis and treatment. Further it is suggested that therapy for these teeth be designed to improve their functional environment and that in many instances removal of root or bone or extraction of the tooth is not necessary. (5) F.I. was detected more frequently in maxillary molars by radiographic examination than by clinical examination. On the other hand F.I. was detected more frequently in mandibular molars by clinical examination than by radiographic examination.

Adult↗
PubMed1999

Treatment of molar furcation involvement using root separation and a crown and sleeve-coping telescopic denture. A longitudinal study.

Because of the inconsistent results of periodontal and prosthetic therapy, periodontists may choose to treat maxillary molar furcation involvements (FI) with poor root morphology utilizing a root resection technique (RRT). In addition, poor root morphology of the remaining root following RRT is usually considered a high risk factor for long-term periodontal and prosthetic success. The purpose of this retrospective study was to investigate the differences in the clinical periodontal parameters between molar abutments with and without molar root separation and/or resection (RSR) before and after periodontal and prosthetic therapy, using a crown and sleeve-coping telescopic denture (CSCTD). A total of 85 molars (47 maxillary and 38 mandibular) were treated in 25 subjects. There were 33 abutments without root separation/resection and 52 abutments with RSR. Forty-three CSCTD were placed, 23 in the maxillary arch and 20 in the mandibular arch. The mean observation period was 6.7+/-1.9 years (range, 5 to 13 years). The plaque index, gingival index, probing depth, clinical attachment level, and alveolar bone change were recorded. The differences in these parameters before and after periodontal and prosthetic therapy between the advanced furcation-involved molars with and without RSR were evaluated. The results revealed a remarkable improvement in the periodontal parameters in advanced Class II and Class III FI in molars with RSR as compared to those without RSR. It was, therefore, concluded that molar abutments with RSR in conjunction with a specifically designed telescopic device provide a modified approach for treating molars with advanced Class II and III FI.

Adult↗
PubMed1989

[Study on grinding movements in chewing. 2. Relationship between grinding movement in chewing-like empty jaw movement and occlusal form of molar].

The purpose of this study is to clarify the relationship between the occlusal form of a molar and mandibular movement. For this purpose I measured the occlusal form of the upper first molar, and the 3-dimensional movement of the lower first molar during the grinding movement in chewing-similar to empty jaw movement. In this study the following three parameters were analyzed.; (1) the distance between the upper and lower first molars in the lateral occlusal position, (2) the inclination of the cusp-slope, (3) the inclination of the lower first molar path. Results were follows: 1) On the working side, the inclination of the cusp-slope is closely connected to that of the path, 2) On the non-working side, the correlation between the inclination of the cusp-slope, and that of the path was so weak, as to be statistically insignificant. 3) The distance between the molars tended to increase as the inclination of the path steepened. This tendency was marked on the non-working side. The results mentioned above proved that, in cases with steeper anterior guidance, the upper and lower first molars disclude more on both the working and non-working sides. On the working side, however, the steeper cusp-slope prevents excessive disclusion of molars.

Dental Occlusion↗
PubMed1989

[Frequency of three-rooted mandibular first molars. Survey by x-ray photographs].

The frequency of three rooted mandibular first molars was surveyed. Subjects were of 1,353 male and female students trained in radiology at Fukuoka Dental College whose average age was 24.3 years old. Dental (complete radiographic survey using 14 films) and panoramic radiographs of their mandibular first molars were taken during a period of 9 years from 1978 to 1986. The results were as follows: 1) The number of the three-rooted mandibular first molars was 440 (18.8%) of 2,331 teeth, including 240 (20.6%) of 1,163 in the right side and 200 (17.1%) of 1,168 in the left. 2) 274 (11.8%) of the three-rooted mandibular first molars were identified by radiographs of the premolar region, 42 (1.8%) by radiographs of the molar region, 124 (5.3%) by radiographs of both the premolar and the molar region. 3) Panoramic radiography identified 70 (15.9%) out of 440 three-rooted mandibular first molars. 4) 136 (12.7%) of 1,070 subjects who had bilateral mandibular first molars had three-roots on both sides 127 (11.9%) of 1,070 had them on one side.

Adult↗
PubMed2001

Pathologic changes in the pericoronal tissues of unerupted third molars.

OBJECTIVE: The purpose of this study was to determine whether the incidence of pathologic conditions affecting the pericoronal tissue of unerupted third molars justifies their routine removal. METHOD AND MATERIALS: The pericoronal tissue associated with completely unerupted third molars was submitted for histologic examination after surgical tooth removal was performed in 37 males and 55 females, aged 13 to 63 years. The 104 unerupted third molars comprised 68 mandibular third molars (65.38%) and 36 maxillary third molars (34.62%). RESULTS: The incidence of normal tissue of a dental follicle was 41.35%, and the incidence of pathologic tissue was 58.65% (dentigerous cyst, 50.96%; chronic nonspecific inflammatory tissue, 4.81%; odontogenic keratocyst, 1.92%; ameloblastoma, 0.96%). The incidence of pathologic conditions was higher than that of normal conditions in all third molar positions. In younger patients, normal tissue was more commonly found, but in patients older than 20 years, the incidence of pathologic tissue was higher than the incidence of normal tissue. CONCLUSION: Unerupted third molars should be removed before pathologic changes can occur in their pericoronal tissues. This justifies routine removal of unerupted third molars from patients older than 20 years.

Adolescent↗
PubMed2001

[A comparative study of clinical application of two types appliances for maxillary molar distalization].

OBJECTIVE: The aim of this study is to evaluate advantages and disadvantages of two types of appliances for maxillary molar distalization. METHODS: Totally, 28 patients with class II malocclusion resulting from molars shifting mesially were treated using two different molar distalization methods, including using removable and fixed appliances. An intra-oral removable acrylic appliance with headgear for extra-oral traction resulted in tipping the maxillary first molars distally. The modified rapid helix expansion appliance (MRHEA), which consisted of bands, anchorage teeth, Nance palatine bases, helix bars and connecting rods, made the maxillary first molars move parallel distally. RESULTS: The desired efforts were gained in 7 or 9 months by using removable appliances, but only 2 or 2.5 months if using MRHEA. The treatment results of using removable appliances were dependent on patients' cooperation, however, the method of using fixed appliance overcame some shortcomings of other molar distalization techniques, and this appliance would not lead to the distal inclination of the crown of the shifted teeth. CONCLUSION: These two methods could convert the class II molar relationship to class I. The MRHEA can save much chair-side time, and shorten the period of treatment, move molars distally parallel.

Child↗