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At least 433 records · Page 24Linked to original sources
PubMed2001

Application of the Third Molar Eruption Predictor to periapical radiographs.

The aim of this study was to test whether the Third Molar Eruption Predictor, developed for panoramic radiographs, can also be applied to periapical radiographs. The Third Molar Eruption Predictor is a transparent device (US patent 5,816,814), not commercially available, and developed for prediction of future eruption or impaction of third molars. The material consisted of periapical radiographs of mandibular third molars taken from the lateral projection without angulation of the central beam. The radiographs taken at the mean age of 20.6 years (SD +/- 1.4 years) were retrospectively available from a four-year follow-up study of third molars carried out at the University of Copenhagen, Denmark. Initially unerupted or partially erupted third molars (n=43) in 28 dental students were analyzed. Clinical statuses of the third molars were available at baseline and four years later. The device was calibrated using the method of simple proportions and Bayes' Decision Theory. The predictions made with the calibrated device were in conformity with the final clinical outcome in 84% of the cases. It was concluded that the Third Molar Eruption Predictor may also be used on periapical radiographs after calibration of the device.

Adult↗
PubMed1984

The effects of space closure of the mandibular first molar area in adults.

There is little information regarding the orthodontic closure of remodeled, edentulous spaces in the posterior area of the mandible. The present study was undertaken to determine the dental and periodontal changes that occur when mandibular first molar areas are closed in adults. Fourteen adult patients were selected from private orthodontic practices. Pre- and posttreatment study models were used to measure the mesiodistal length of the edentulous space and the buccolingual width of the alveolar ridge. The amount of crown and root movement of the second molar and premolar was measured from lateral cephalometric radiographs. From pre- and posttreatment panoramic or periapical radiographs, the anatomic changes of the second molar and adjacent periodontium were also measured. Every case showed significant space closure (x = 6.2 mm) ranging from 2.7 to 11.5 mm. There was crestal bone loss (x = 1.3 mm) mesial to the second molar in all but five cases. These latter cases showed bone addition. As the molar moved mesially , the alveolar ridge increased in width an average of 1.2 mm. The adult patient who showed the greatest amount of space closure and the least amount of molar bone loss had (1) mesiodistal space of 6.0 mm, (2) buccolingual ridge width of 7.0 mm, and (3) mesial molar bone level 1.0 mm apical to the cementoenamel junction. The results of this study indicate that space closure is not only possible but may aid the treatment of certain cases. Space closure should be considered as a potential solution to the absence of mandibular first permanent molars.

Adult↗
PubMed1992

Asymptomatic mandibular third molars: oral surgeons' judgment of the need for extraction.

Ten oral surgeons were asked to judge the need for extraction of asymptomatic mandibular third molars. Thirty-six mandibular third molars with equal distribution of angular position, impaction status, and patient's sex and age were selected. To estimate the consistency of judgment, the 36 cases were duplicated so that, in all, 72 cases were judged. The judgment of the oral surgeons was compared with that of 30 general dental practitioners (GDPs). The number of mandibular third molars the oral surgeons proposed to extract varied from 3 to 21 of 36 teeth. The mean number of molars proposed for extraction was 12 for the oral surgeons and 13 for the GDPs. There was no third molar that all the observers in the two groups agreed should be extracted. About three times as many observers in both groups proposed extraction of molars partially covered by soft tissue. The oral surgeons were unanimous in their judgment not to extract 11 molars, and the GDPs were also unanimous in judgment not to extract two of these. The mean intraobserver agreement within the two groups was comparable, 94% for the oral surgeons and 92% for the GDPs. We conclude that there is a great variation among oral surgeons in their judgment on the need for removal of asymptomatic mandibular third molars. A similar variation in judgment also was observed among GDPs.

Adolescent↗
PubMed1983

Dental nerve regeneration in rats. I. Electrophysiological studies of molar sensory deficit and recovery.

Return of sensory nerve function in rat molars following cut or crush injury to the inferior alveolar nerve (IAN) was measured by observing the jaw opening reflex (JOR) response of the digastric muscle to electrical stimulation of individual molars or the gingiva. The IAN was injured from a lateral approach to the mandibular ramus at a site approximately 2 mm proximal to the incisor apex. Following nerve injury, the JOR threshold to stimulation of the first molars increased 6-fold: preoperative threshold mean = 47.4 +/- 21.3 microA (n = 27), postoperative threshold mean = 248.5 +/- 127.1 microA (n = 25). A 4-fold postoperative increase in JOR threshold was found for the second molars, and the thresholds were not significantly affected for third molars or gingiva. These postoperative results indicated that the major pathway of sensory innervation to the first and second molars was affected by the IAN injury, whereas the third molars and gingiva had alternate sources of innervation which remained unaffected by the IAN injury. At 1 week following injury, there was partial return of sensitivity, by 3 weeks there was approximately 50% recovery, and by 6 weeks complete return to normal JOR thresholds was found. The degree of sensory deficit, as reflected in JOR inhibition, and the rate of recovery were not significantly different after cut or crush injury in these experiments; however, there was a tendency for greater sensory loss and for more rapid recovery after crush injury. This study forms the basis for a subsequent autoradiographic analysis of nerve location in rat molars of known sensory deficit, partial recovery, or full sensory recovery.

Alveolar Process↗
PubMed2003

Retained deciduous mandibular molars in adults: a radiographic study of long-term changes.

Management of retained deciduous second molars in the absence of permanent successors can be challenging. The purpose of this retrospective radiographic study was to examine long-term changes in retained deciduous mandibular second molars in adult patients. Specifically, we sought to answer the question, "If an adult has a retained deciduous mandibular second molar and a missing successor, is retaining the deciduous molar a viable treatment option?" From more than 6000 adult patients at the University of Iowa College of Dentistry, 20 were identified who initially had at least 1 retained deciduous mandibular second molar without a permanent successor and who had radiographs spanning 5 or more years after the initial visit. The mean (standard deviation) age at the initial examination was 36.1 (12.9) years, the mean age at the final examination was 48.5 (12.6) years, and the mean examination time span was 12.4 (7.7) years. Of the 28 retained deciduous molars initially identified, 24 (86%) continue to function. The remaining 4 were lost at a mean age of 51.0 (13.9) years and a mean time span after initial examination of 14.3 (10.0) years; this approximates the lifespan of some prosthetic appliances. These 4 mandibular deciduous molars were lost because of caries or periodontal breakdown. Furthermore, we found that the average shortening of all deciduous root lengths was negligible (0.16 mm), and only 6 teeth underwent a change in restoration status. Based on this study in adults and earlier studies in adolescents, we conclude that retaining healthy deciduous mandibular second molars is a viable treatment alternative.

Adult↗
PubMed2005

Effects of cervical headgear and fixed appliances on the space available for maxillary second molars.

INTRODUCTION: This study examined the effects of cervical headgear and fixed appliances on the space available for the eruption of the maxillary second molars. Cervical headgear was the only intervention until a Class I molar relationship was achieved. METHODS: Thirty-four patients (18 girls, 16 boys) with Class II molar occlusions, treated without extractions, were included in this study. Five linear and 4 angular cephalometric measurements were made from pretreatment and posttreatment radiographs. RESULTS: Treatment prevented the mesial drift of the maxillary first permanent molars and the forward displacement of the maxilla, displaced the pterygomaxillary fissure posteriorly, and uprighted the first permanent molars. In the male group, the only significant changes were molar uprighting and clockwise rotation of the maxilla. CONCLUSIONS: These results suggest that posterior displacement of the pterygomaxillary fissure by treatment and growth at the maxillary tuberosity compensated for the restricted anterior movement of the maxillary first molars, allowing the second molars to erupt.

Adolescent↗
PubMed2004

Clinical outcome of third molars in adults followed during 18 years.

PURPOSE: The aim of the present study was to follow the clinical changes in third molar status during an 18-year period in patients aged 20 to 38 years. PATIENTS AND METHODS: The series consisted of 118 subjects (37 men and 81 women). In the beginning of the study, the mean age was 20.2 years (SD, +/-0.6 year), and at the end, it was 38.6 years (SD, +/-0.6 year). Panoramic radiographs were taken at baseline and at age 38. All of the subjects were clinically examined at baseline and at the end of the study. A portion of the subjects (n = 69) were also examined at age 32. RESULTS: Most of the initially unerupted third molars were removed during the follow-up period (73%, maxilla and mandible together). More than half of the initially partially erupted third molars were removed during the follow-up period (64%, maxilla and mandible together). The percentage of erupted third molars found in the mouth at age 38 increased significantly depending on the initial status. Of the initially unerupted, partially erupted, or erupted third molars, 10%, 33%, and 50%, respectively, were erupted at age 38 (maxilla and mandible together). Changes in the status of third molars continued from age 32 to age 38, although to a lesser extent (8%). The 3 third molars with advanced eruption were all maxillary teeth in men. CONCLUSION: Third molars undergo continuous clinical change on a reduced scale at least up to the age of 38 years.

Adult↗
PubMed2005

Use of autologous platelet-rich plasma (PRP) in periodontal defect treatment after extraction of impacted mandibular third molars.

PURPOSE: The extraction of mesioangular impacted third molars may cause multiple periodontal defects at the distal root of the second molar. Platelet-rich plasma (PRP) is a material containing many autologous growth factors that may be used in repairing and preventing periodontal complications at the distal root of the second molar adjacent to the extracted third molar. PATIENTS AND METHODS: We analyzed the effects of autologous PRP on periodontal tissues after extraction of the third molar in 18 young patients (age, 21-26 years). Inclusion criteria were the presence of a pocket distal to the mandibular second molar with a probing depth>or=7.5 mm and a probing attachment level>or=6 mm. RESULTS: We observed, at 12 weeks after surgery, a notable reduction in the probing depth and an improvement in the probing attachment level in those cases treated with PRP compared with the controls, as well as formation of new bone tissue in the bone defect. CONCLUSION: We showed that PRP is effective in inducing and accelerating bone regeneration for the treatment of periodontal defects at the distal root of the mandibular second molar after surgical extraction of a mesioangular, deeply impacted mandibular third molar.

Adult↗
PubMed2006

Chronic oral inflammation and the progression of periodontal pathology in the third molar region.

PURPOSE: To assess the association between risk markers of chronic oral inflammation and changes over time in periodontal probing depth (PD) in the third molar region, the distal of a second molar, or around a third molar. SUBJECTS AND METHODS: The data from these analyses are part of a study of subjects enrolled with 4 asymptomatic third molars with adjacent second molars in an institutional review board-approved longitudinal trial. Full-mouth periodontal probing was conducted at enrollment and follow-up. Enrollment levels of periodontal pathogens and gingival crevicular fluid inflammatory mediators were assayed as indicators of the degree of oral inflammation. Subjects were categorized as those who had at least a 2 mm change in periodontal PD between baseline and follow-up in the third molar region and those who did not. The relationship between aggregated subject baseline PD, levels of periodontal pathogens, and gingival crevicular fluid IL-1 beta, and the proportion of subjects with changes in PD >or=2 mm versus those with PD <2 mm were compared with Cochran-Mantel-Haenzsel statistics. Level of significance was set at 0.05. Risk assessment models for a change in PD >or=2 mm were developed using logistic regression analysis. RESULTS: Twenty-four percent of 254 subjects exhibited a change in PD from baseline to follow-up of >or=2 mm in the third molar region. Of these, 95% had a baseline PD of >or=4 mm. Both high (>or=10(5)) "orange" and "red" complex bacteria and PD of >or=4 mm detected at enrollment were significantly associated with a change in PD >or=2 mm. Odds of a change in PD >or=2 mm were increased if baseline pathogen levels were >or=10(5) or a PD of >or=4 mm was detected at enrollment. CONCLUSION: Our findings are consistent with chronic oral inflammation leading to a progression of periodontal disease in the third molar region.

Adolescent↗
PubMed2000

Long-term evaluation of estimates of need for third molar removal.

PURPOSE: The aim of this study was to evaluate the estimates on need for third molar removals made at age 20 after 12 years. PATIENTS AND METHODS: The series consisted of 81 university students followed from age 20 to 32 years. At baseline and at study end, these students were clinically examined, and panoramic radiographs were taken. At baseline in 1982, a qualified oral surgeon had made estimates on need for removal of third molars within 5 years; 75% of students needed removals. Actual treatment performed was evaluated after 12 years. A questionnaire served to determine symptoms related to third molars during the 12-year period. RESULTS: During the follow-up, one or more third molars had been removed from 67% of the former students. A total of 155 third molar removals had been estimated, but by age 32 years the percentage actually removed was only 59%. Of the 79 third molars taken out at the Finnish Student Health Service, 77% were initially estimated to need a surgical procedure, but actually 66% were simply extracted. Most were removed at around age 27 years. According to the questionnaire, 67% of the students were asymptomatic in the third molar region during 12 years. CONCLUSION: Because need for surgical removal decreases during early adulthood, routine prophylactic extraction of asymptomatic third molars in young adults cannot be recommended. Well-defined indications for prophylactic removals are needed.

Adult↗
PubMed2003

Radiographic evaluation of third molar development in Spanish children and young people.

Third molar development was evaluated in 786 young people aged between 4 and 20 years, all patients at the School of Dentistry of the University of Granada. The development of third molars and of mandibular second premolars and second molars was determined according to the stages proposed by Nolla. The onset of mandibular third molar formation was observed at very variable ages in this series, ranging from 5.86 to 14.66 years. The first developmental stages of maxillary third molars are not usually visible radiographically, which can lead to an incorrect diagnosis of agenesis. We found no significant relationship between the gender or age of the patient and the presence or absence of third molars. However, the presence/absence of the third molar can be predicted in 82.82% of cases when there is some degree of calcification of mandibular second molars and second premolars.

Adolescent↗
PubMed1999

Symptoms of unerupted mandibular third molars.

OBJECTIVE: The purpose of this study was to analyze the occurrence of symptoms in patients with unerupted mandibular third molars and to investigate the associated pathoses. STUDY DESIGN: Through a review of clinical records and periapical radiographs of completely unerupted and partially erupted mandibular third molars, a retrospective study was carried out. For each axial inclination, symptoms and pathoses associated with these teeth were analyzed. Statistical differences were tested by chi square analysis. RESULTS: Most of the patients were between 16 and 30 years of age. In 83% of cases, the mandibular third molars were partially erupted; in the other 17% of cases, the mandibular third molars were completely unerupted. Pain was the most frequent symptom in both groups. Pericoronitis was found mostly in third molar teeth with vertical and distal inclinations (P< .05), whereas caries was found mainly in mesially tipped third molars (P < .05). CONCLUSIONS: Most of the patients were in the third decade of life. Partially erupted mandibular third molars had more symptoms than completely unerupted teeth. Pain and pericoronitis were the most common problems in patients with unerupted third molars.

Adolescent↗
PubMed1977

The etiology and prediction of mandibular third molar impaction.

1. Skeletal Class II dental base relationship with a shorter, narrower, more acute angled madible was found in association with impacted third molars, compared with erupted teeth. 2. These differences were found at age 18+ years but were less obvious at age 10 to 11 years. 3. There was a reduced amount of mandibular growth in impacted third molar cases. 4. There was a slight tendency for impacted third molars to be larger than those which erupted. 5. The presence of a space between second and third molars in the early stages of development is not an indication that the third molar will erupt. 6. The developmental angulation of the third molar to the mandibular plane was higher in the impacted third molar group. 7. Accurate prediction of third molar impaction from radiographic measurements is not possible at age 10 to 11 years.

Adolescent↗
PubMed1985

Extraction of four second molars.

The cases presented here clearly demonstrate that the removal of second permanent molars can be effective in many cases where removal of first or second bicuspids would otherwise be recommended. Third molars can be useful components of the dentition. The Author has found that when the proper diagnosis is made and the extraction of second molars is recommended, third molars will assume their position in juxtaposition to the first permanent molar in over 75% of the cases. Although we used several methods of measuring developing mandibular third molars, we were unable to predict accurately and consistently which teeth would erupt in the proper upright position (Fig. 10). With rare exception, maxillary third molars will erupt uneventfully, but in the mandibular arch there is a much greater possibility that it may be necessary to upright or reposition the third molars.

Adolescent↗
PubMed1992

A comparison of the effects of first premolar extractions on third molar angulation.

The effect of third molars on the stability of orthodontic treatment has been studied extensively. Yet the effect of orthodontic treatment, particularly premolar extractions, on third molars has not been substantially studied. The purpose of this investigation was to compare the changes in third molar angulation in patients treated with and without extractions. Records of 45 Class I, nonextraction and 33 Class I, first premolar extraction patients were examined. The pretreatment and posttreatment pantographs were digitized, and the angles between the third molar long axes and the occlusal plane were measured. Changes in third molar angulation from pretreatment to posttreatment for the two groups were compared for statistical differences using a Student's t-test. Statistical analysis revealed there were no significant differences in the change in third molar angulation in either group. On average, the maxillary and mandibular third molars showed an improvement in angulation relative to the occlusal plane. The results suggest that factors other than first premolar extractions may influence third molar angulation.

Adolescent↗
PubMed2004

Statistical evaluation of possible factors affecting the sagittal position of the first permanent molar in the maxilla.

A cephalometric analysis was designed to evaluate several factors that may affect the sagittal position of the maxillary first permanent molar. A total of 184 Class II and Class I malocclusion patients were randomly selected before orthodontic treatment. The mandibular and palatal planes were related to Frankfort Horizontal and used to create the interjaw or B angle. Age and cephalometric landmarks (Ba, N, point A, pterygomaxillary fissure, and maxillary molars) were projected at right angles to the Frankfort Horizontal for effective length. Actual maxillary length and actual molar location were determined by projecting landmarks at right angles to the palatal plane. Correlation coefficients and P values were used to evaluate the data with a minimal significance value of .05 to determine a 95% confidence level. A statistically significant linear and proportional positive correlation (P < .0001) existed between molar location, age, and maxillary size. There was a strong negative correlation (P < .0001), both linearly and as a proportion of the actual length of the maxilla, between the actual position of the maxillary molar and the interjaw and mandibular plane angles. A significant correlation also existed between the molar position and palatal plane angles. The results show that increased interjaw, mandibular, and palatal plane angles are accompanied by a more posterior position of the maxillary first molar in the maxilla, whereas the molar occupied a continuing more forward position in the maxilla with increasing age, cranial base length, and maxillary size.

Age Factors↗
PubMed2005

Anchorage provided during intra-arch distal molar movement: a comparison between the Nance appliance and a fixed frontal bite plane.

The aim of this retrospective study was to evaluate and compare the anchorage provided with the Nance appliance (NA) and the fixed frontal bite plane (FBP) during intra-arch distal molar movement. After a sample size calculation, 20 patients were recruited and randomly selected for each group from patients who fulfilled the following criteria: use of an intra-arch Ni-Ti coil appliance with either NA or FBP to provide anchorage during a six-month molar distalization period, no orthodontic treatment before molar distalization, and first and second maxillary molars in occlusion. The outcome measures assessed were anchorage loss, ie, anterior movement of maxillary central incisors, distal movement of maxillary molars, and bite opening effect. The mean age in the NA group was 14.7 years (SD 1.09) and in the FBP group 15.0 years (SD 0.99). The data revealed that the maxillary central incisors moved anteriorly 1.4 mm in the NA group and 1.9 mm in the FBP group. The difference in anchorage loss was not significant. The mean amount of molar distalization within the maxilla was 1.7 mm in the NA group and 1.8 mm in the FBP group. In both groups, the overbite was significantly reduced and the overbite was decreased significantly more in the FBP group. Because neither the NA nor FBP provided stable anchorage, a second treatment phase is recommended to reverse the anchorage loss after distal molar movement. If molar distalization is planned in deep bite cases, the FBP is the anchorage system of choice.

Adolescent↗
PubMed2000

Root canal anatomy of maxillary first and second permanent molars.

AIM: The aim of this investigation was to study the root canal anatomy of maxillary first and second molar teeth from an Irish population sample using a clearing technique. METHODOLOGY: Eighty-three extracted permanent maxillary right first molars and 40 permanent right maxillary second molars were included in this investigation. The specimens were demineralized and then cleared using methyl salicylate. The following observations were made: number of roots, prevalence of fusion, types of root canals using Vertucci's classification, presence and position of lateral canals, presence and position of transverse anastomoses, number and position of apical foramina and the frequency of occurrence of apical deltas. RESULTS: Eleven per cent of maxillary first molars and 43% of maxillary second molars had fused roots. A total of 78% of mesiobuccal roots in maxillary first and 58% in maxillary second molars had two canals. Sixty-two per cent of maxillary first and 50% of maxillary second molars had two apical foramina. There was a significant inverse relationship between age and the occurrence of two canals and between age and the occurrence of transverse anastomoses in both tooth morphotypes (P < or = 0.05). CONCLUSIONS: It is concluded that a significant proportion of the first and second molar specimens studied had two canals in the mesiobuccal root (78% and 58%, respectively) and that the occurrence of two canals and transverse anastomoses decreased significantly with increasing age.

Adult↗