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PubMed1999

Radiographic evaluation of mandibular third molar eruption space.

OBJECTIVE: The purpose of this study was to investigate variables in third molar and arch dimensions among subjects with impacted and erupted mandibular third molars. STUDY DESIGN: Standardized panoramic radiographs were taken for 134 subjects (60 males and 74 females with 213 third molars) with an average age of 19.8 years. For the impacted group, only those who had mesioangular inclination of the third molars were recorded. The radiographic features studied were angulation of tooth, level of eruption, development of root, mesiodistal crown width, retromolar space, and gonial angle. RESULTS: Third molar angulation in the impacted group (69 subjects with 101 third molars) averaged 16.28 degrees (SD +/- 11.88 degrees), with no significant gender differences. The retromolar space was significantly smaller in the impacted group than in the erupted group (P < .001). This space was also the only significant variable (P < .05) associated with lateral asymmetry in the eruption/impaction status of third molars. In the impacted group, 83% of subjects had third molar space/crown width ratios less than 1, whereas in the erupted group 69% had ratios of at least 1. The average space/crown width ratios in the impacted and erupted groups were 0.78 and 1.06, respectively (P < .001). The impacted and erupted groups did not differ significantly with respect to mesiodistal crown width and gonial angle. Approximately 76% of impacted third molars had complete root formation, 20% had two thirds root formation, and only 4% displayed one third root formation. Of the impacted third molars, 66% were partially erupted and the rest were unerupted. There was a strong positive relationship between frequency of third molar impaction and degree of angulation (P < .001), but the former was inversely associated with retromolar space (P < .001). CONCLUSIONS: The most significant variable associated with third molar impaction is inadequate space. The vast majority of impacted third molars had space/crown width ratios of less than 1.

Adolescent↗
PubMed2003

Molar apicectomy with amalgam root-end filling: results of a prospective study in two district general hospitals.

AIM: To determine the five-year success rates, site or sites of failure, prognostic indicators and lower lip morbidity associated with molar apicectomy using amalgam root-end filling. DESIGN: Multicentre, prospective study. SETTING: The departments of oral and maxillo-facial surgery in two district general hospitals. METHOD: One thousand and seven molar apicectomy procedures, combined with amalgam root-end filling were expedited during the period 1974-1995. A five-year review of each operated tooth was carried out or attempted between 1979-2000. RESULTS: Of the 790 (78%) operated molars successfully reviewed at 5 years or later 451 (57%) exhibited 'complete healing' and 39 (5%) 'uncertain healing'. Three hundred (38%) were classified as 'unsatisfactory healing' (failures), and these included 12 which were assumed to be of periodontal origin. Whilst longitudinal root fracture, perforation and/or infection in the furcation, periodontal disease or a non-restorable crown accounted for treatment failure and often the need to remove teeth subsequently, the study probably pointed to the apical ends of the roots rather than the furcation as being the major sites at which 'unsatisfactory healing' occurred. Mandibular first molars attracted the highest 'complete healing' rate (60%) and mandibular second molars the lowest (46%). 'Good' root canal treatment (RCT) at the outset improved the prognosis of a root-end filling (REF) whilst the absence of RCT compromised it. Cystic change pointed to a better prognosis than apical granulomatous change as did a deep compared with a shallow 'bone cuff'. Disease at the furcation suggested a worse prognosis. Teeth which showed 'complete healing' at 1 year had a 75% probability of maintaining this outcome at 5 years. Sensory disturbance of variable duration occurred in the lower lip following 20-21% of mandibular molar procedures. In the majority of cases (79-80%) this had remitted within 3 months. A permanent deficit occurred in 8 patients (1%) where the apicectomy could definitely be incriminated as causative. Four were associated with first molar apicectomy and four with second molar apicectomy. CONCLUSIONS: Molar apicectomy with amalgam root-end filling attracts an overall 'complete healing' rate at 5 years of 57%, the results being best with mandibular first molars and worst with mandibular second molars. The prognosis is also better where there is 'good' initial orthograde root filling, an associated radicular cyst as compared with granulomatous change and where the buccal sulcus is deep rather than shallow. It is worse when orthograde root filling is absent and when there is disease in the furcation. 'Complete healing' at 1 year can be expected to be maintained at 5 years in 75% of cases. The commonest site of subsequent periradicular rarefaction seems to be 'apical' whilst failure at the furcation is probably comparatively rare. There is a threefold increase in the occurrence of permanent lower lip sensory impairment following second molar surgery in comparison with first molar surgery, the overall incidence being 1%.

Adult↗
PubMed2005

Hypomineralized molars and incisors of unknown origin: treatment outcome at age 18 years.

OBJECTIVE: To assess the outcome of treatment of hypomineralized molars and incisors of unknown aetiology (MIH) in 18-year-olds. DESIGN: A follow-up study including clinical examination, panoramic radiography and intraoral photos. SAMPLE AND METHOD: Seventy-six individuals treated at the Eastman Dental Institute in Stockholm during 1978-2001 with the diagnosis MIH. Severity of enamel defects in molars and incisors, prevalence and distribution of extracted molars, type, quality and median duration of restorations, periradicular condition of affected molars, dental occlusion and space closure in cases of extraction, as well as the individual's satisfaction with the treatment, were assessed. RESULTS: Severe defects with enamel surface breakdown in all four molars occurred in 42% of the individuals and 29% had at least one incisor with yellow/brown opacity in the enamel. At follow up, 42% of the individuals had at least one molar extracted; 18% had all four molars extracted. The median duration of the molar restorations (n = 153) was 5 years. Of the individuals with restored molars, 48% had at least one unacceptable restoration. Periradicular pathology was observed in three molars. The sagittal relations did not differ between individuals with and without extraction of molars. Space closure was acceptable in 87% of the individuals with extracted molars. Eighty percent were satisfied with the treatment. CONCLUSIONS: Extraction of molars with severe enamel defects gave good or acceptable results in a majority of the patients while conservative restorative treatment resulted in a need for additional treatment in approximately half of the patients.

Adolescent↗
PubMed1997

Relationship between molar root fusion and localized periodontitis.

We investigated the relationship between molar root fusion and localized periodontitis in this study. A total of 143 individuals (1,109 molars) aged 23 to 68 years were examined for the presence of molar root fusion at diseased and healthy sites. Molar root fusions were diagnosed by periapical radiographs and clinical probing. Periodontal parameters measured included probing depth (PD), clinical attachment loss (CAL), gingival index (GI), and plaque index (PLI) around fused molars. Results indicated that the prevalence of molar root fusions in males and females was 15.2% (93/612) and 32.2% (160/497), respectively. The distribution of molars with root fusions occurs in the following order: maxillary second molars (51.8%), mandibular second molars (32.3%), maxillary first molars (5.7%), and mandibular first molars (0%). Statistically significant differences were observed between molar root fusions at healthy and diseased sites with respect to PLI, GI, PD, and CAL. The highest prevalence of molar root fusion was observed in females.

Adult↗
PubMed1989

[Molar size sequence in seven species of Cercopithecidae].

The size sequence of the molar teeth in three genera, including seven species, of the Cercopithecidae was examined on the basis of mesiodistal and buccolingual crown diameters, and rectangle measurements (mesiodistal d. X buccolingual d.). The determination of molar size order was estimated by the three methods of mean values, size sequences and reductive indices (M2/M1, M3/M1). The results obtained are summarized as follows: 1. The molar size sequence of the seven species. The pattern of sequence in the molars of the Cercopithecidae was divided into six types: (I) M1 less than M2 less than M3 or (M1M2) less than M3, (II) M1 less than (M2M3), (III) M1 less than M3 less than M2, (IV) (M1M2M3), (V) (M3M1) less than M2, and (VI) M3 less than M1 less than M2 or M3 less than (M1M2). 2. The upper molars. i) The most frequent pattern of mean values found was type II for all the species of the Macaca and Colobus. The two species of Cercopithecus showed predominantly the characteristics of types III, IV and V. ii) The molar size sequence individual data revealed that in the mesiodistal crown diameter types I and II were distributed frequently in the Macaca, types IV and V in the Colobus, and type VI in the Cercopithecus. The reduction of the third molar, therefore, seemed to be more pronounced in the Cercopithecus when compared with the other two genus, Macaca and Colobus, because type VI is the type with more size reduction in the third molar. In the case of the buccolingual crown diameters, the most common size sequences were found in types II and III for the Macaca and Colobus. In the Cercopithecus, however, type V exceeded other types in frequence. iii) The results of the reductive indices showed that the second molars in the Colobus were greatly reduced compared to the first, followed by those of the Cercopithecus and Macaca. In the third molar reduction, the Cercopithecus had a relatively small third molar compared to the first, following the Colobus and Macaca. 3. The lower molars. i) The pattern in the mean values were frequently found to be type I for the Macaca and Colobus, and types III and II for the Cercopithecus. ii) The size sequence in the frequency of the mesiodistal crown diameter was well presented in type I for the Macaca and Colobus, while types IV and V were distributed frequently for Cercopithecus in which the reduction of the third molar was noticeable.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

[The relation of pericoronitis to the position of the mandibular third molar].

Pericoronitis is the most commonly encountered pathologic condition involving the mandibular third molar. Because of the dangers associated with mandibular third molar pericoronitis, prophylactic extraction of third molar at high risk has been recommended. We studied 411 patients with mandibular third molar pericoronitis by clinical symptoms and radiographic measurement of mandibular third molar height, wideth and angulation. The results were as follows: 1. Mandibular third molar pericoronitis is frequently seen in third decade and there are no sexual difference significantely. 2. In inflammatory type of mandibular third molar pericoronitis, chronic pericoronitis occured more frequently than acute type. 3. In relation to angulation and height, mandibular third molar most likely to be afflicted with pericoronitis is vertical eruption at occlusal plane of the second molar. 4. In relation to angulation and width, it appears that the position of the mandibular third molar most likely to be afflicted with pericoronitis is in a vertically erupted tooth of which the space between the ramus and the distal side of the second molar is less than the mesiodistal diameter of crown. (Class II). 5. In relation to height and width, it appears that the position of the mandibular third molar most likely to be afflicted with pericoronitis is class II width (described above)at occlusal plane of the second molar.

Adolescent↗
PubMed1989

[A case of bilateral impaction of the lower second molars].

A case of bilateral impaction of the lower second molars is presented. A 15-year-old boy with an ill feeling at the right lower first molar was referred to us. X-ray examination revealed bilateral impaction of the lower second molars and the presence of bilateral teeth that seemed to be the unerupted third molars distal to the impacted second molars. Furthermore, a radiolucency approximately 3 X 3 mm in size was detected in the mesioapical region of the right lower first molar. These impactions were managed under local anesthesia by extraction of the right lower first molar and fenestration of the right lower second molar. After approximately 4.5 months, the right lower third molar was extracted. It was further followed approximately 1 month later by extraction of the left lower third molar and ipsilateral fenestration of the lower second molar. As a result, the right lower second molar erupted but it was considerably inclined in a mesial direction. The left lower second molar erupted normally almost up to the occlusal plane. In the absence of systemic abnormality, facial trauma, and maldevelopment of the jaw, impaction seemed to have been closely associated with some unknown local factor.

Adolescent↗
PubMed1996

[The study of molar furcation involvements in adult periodontitis. II. Age, sex, location and prevalence].

The purposes of the study were as follows: (1) to evaluate the molar furcation involvement and number of molar correlated with age and sex; and (2) to study the relationship between the means of alveolar bone loss and associated factors of molar furcation involvements (FIs). 1102 molars (703 males and 399 females) were measured in 219 individuals (136 males and 83 females) for the alveolar bone loss and associated factors of molar furcation involvements. Based on the results, we conclude the following: (1) the higher prevalence of FI was in the mandibular first molar (94.6%), whereas the lowest prevalence of FI was in maxillary second molar; (2) except for the mandibular first molar, the prevalence of molar FI markedly increased with an increased age group (16 & 26, r = 0.335, p < 0.01; 17 & 27, r = 0.345, p < 0.01; 37 & 47, r = 0.239, p < 0.01); (3) the prevalence of molar FI was significantly higher in males than in females (p < 0.05); (4) the mean number of molar FI was significant greater in males (mean = 3.45) than in females (mean = 2.69); (5) factors such as age (r = 0.222, p < 0.01), sex, (r = 0.145, p < 0.05), number of remaining teeth (r = -0.330, p < 0.01) and molar FI (r = 0.471, p < 0.01) are strongly associated with the mean alveolar bone loss of molars.

Adult↗
PubMed1988

Changes in the molar relationship between the deciduous and permanent dentitions: a longitudinal study.

The purpose of this study was to describe the changes in the molar relationship from the deciduous dentition to the permanent dentition in 121 subjects from the Iowa Longitudinal Growth Study. In addition, an attempt was made to determine the association between the various dentofacial variables and the changes in the molar relationship in 55 persons (33 male and 22 female subjects) with normal occlusion. All subjects were evaluated at three stages of dental development: stage I, completion of the deciduous dentition (means age = 4.94 years); stage II, when permanent first molars initially erupt into occlusion (means age = 6.91 years); and stage III, at the completion of eruption of the permanent dentition excluding third molars (means age = 13.01 years). The following sets of variables were evaluated: molar relationship, mesiodistal crown diameters of single and groups of deciduous and permanent teeth, dental arch widths, arch lengths, and various cephalometric dentofacial variables. Correlation coefficients and regression analyses were used to assess the relationships between these measurements and the changes in the molar relationship from the deciduous to the permanent dentition. The findings indicate that of the 242 sides evaluated in the deciduous dentition, 61.6% developed into a Class I molar relationship, 34.3% into Class II, and 4.1% into Class III. Those sides that started with a distal step in the deciduous dentition proceeded to develop into a Class II molar relationship in the permanent dentition. Of the sides with a flush terminal plane relationship in the deciduous dentition, 56% progressed to a Class I molar relationship and 44% to Class II in the permanent dentition. The presence of a mesial step in the deciduous dentition indicates a greater probability for a Class I molar relationship and a lesser probability for a Class II molar relationship. In the 55 subjects who achieved normal occlusion, the magnitude of change in the molar relationship was 1.91 mm in male subjects and 1.64 mm in female subjects. On the average, these cases had a mesial step in the deciduous dentition of 0.8 mm in male subjects and 1.0 mm in female subjects. There was a favorable difference between the maxillary and mandibular leeway spaces of 1.3 mm in male subjects and 1.1 mm in female subjects. There was also a favorable decrease in the Wits appraisal of 1.2 mm in male subjects and 0.6 mm in female subjects.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed2006

Radiographic evaluation of third molar development in relation to chronological age among Turkish children and youth.

A sharp increase in forensic age estimation of living persons has been observed in recent years. However, ethnic populations residing in different countries have been insufficiently analyzed. According to 2004 data compiled by the Essen-based Turkey Research Center, there are 3.8 million Turkish people living abroad, and 3.2 million of them reside in European Union countries. Despite the high number of Turks living abroad, little is known about third-molar development for forensic application in this population. Hence, it was considered worthwhile to determine the developmental stages of the third molar in a group of Turkish population, to assess chronological age estimation based on the developmental stages, and to compare third molar development according to sex, age and location. Orthopantomograms of 1134 Turkish patients, ages 4-20 years were examined and third-molar developmental stages were evaluated based on Demirjian's classifications. Orthopantomograms were scored by two different observers, and Wilcoxon matched-pairs signed-ranks test used to test intra- and inter-observer reliability revealed a strong agreement between both intra- and inter-observer measurements. Linear regression analysis was performed to correlate third-molar development and chronological age, and further statistical analysis was performed to determine the relation between sex, age and location. Results showed a strong linear correlation between age and molar development (males: r(2)=0.57; females: r(2)=0.56). Mineralizations of left and right third molars were compared using Wilcoxon tests, and no statistical differences were found. No significant differences were found in third-molar development between males and females. Mandibular third molar crypt formation was observed in 2.4% of patients at age seven and maxillary third molar crypt formation was observed in 1.3% of patients at age seven. A strong correlation was found between third-molar development and chronological age. Among the Turkish population, third molar crypt formation is observable at as early as 7 years in both the mandible and maxilla. Agenesis can be determined conclusively if no radiolucent bud is present by age 14.

Adolescent↗
PubMed2005

Molar scaling in strepsirrhine primates.

We examined how maxillary molar dimensions change with body and skull size estimates among 54 species of living and subfossil strepsirrhine primates. Strepsirrhine maxillary molar areas tend to scale with negative allometry, or possibly isometry, relative to body mass. This observation supports several previous scaling analyses showing that primate molar areas scale at or slightly below geometric similarity relative to body mass. Strepsirrhine molar areas do not change relative to body mass(0.75), as predicted by the metabolic scaling hypothesis. Relative to basicranial length, maxillary molar areas tend to scale with positive allometry. Previous claims that primate molar areas scale with positive allometry relative to body mass appear to rest on the incorrect assumption that skull dimensions scale isometrically with body mass. We identified specific factors that help us to better understand these observed scaling patterns. Lorisiform and lemuriform maxillary molar scaling patterns did not differ significantly, suggesting that the two infraorders had little independent influence on strepsirrhine scaling patterns. Contrary to many previous studies of primate dental allometry, we found little evidence for significant differences in molar area scaling patterns among frugivorous, folivorous, and insectivorous groups. We were able to distinguish folivorous species from frugivorous and insectivorous taxa by comparing M1 lengths and widths. Folivores tend to have a mesiodistally elongated M1 for a given buccolingual M1 width when compared to the other two dietary groups. It has recently been shown that brain mass has a strong influence on primate dental eruption rates. We extended this comparison to relative maxillary molar sizes, but found that brain mass appears to have little influence on the size of strepsirrhine molars. Alternatively, we observed a strong correlation between the relative size of the facial skull and relative molar areas among strepsirrhines. We hypothesize that this association may be underlain by a partial sharing of the patterning of development between molar and facial skull elements.

Animals↗
PubMed1999

Canal morphology of maxillary molars: clinical observations of canal configurations.

An examination of 1732 conventionally treated maxillary molars was made in an attempt to determine the percentage of MB2 canals that could be located routinely. The teeth examined were 1096 first molars, 611 second molars, and 25 third molars. The results were recorded on a modified computer program over an 8-yr period of time. An interesting trend was noted. The MB2 canal was found in 802 (73.2%) first molars, 310 (50.7%) second molars, and 5 (20.0%) third molars. It occurred as a separate canal in 54.9% of first molars, 45.6% of second molars, and joined in all third molars. However, as the operator became more experienced, scheduled sufficient clinical time, routinely employed the dental operating microscope, and used specific instruments adapted for microendodontics, MB2 canals were located in 93.0% of first molars and 60.4% in second molars.

Dental Pulp Cavity↗
PubMed1996

Evaluation of an intraoral maxillary molar distalization technique.

The purpose of this study was to determine the effects of the pendulum appliance on distalization of maxillary molars and the reciprocal effects on the anchor premolars and maxillary incisors. Initial and follow-up cephalometric radiographs were obtained on 41 subjects (26 girls and 15 boys) who were treated with the pendulum appliance for bilateral distalization of the maxillary first molar teeth, for correction of the Class II molar relationship or for gaining space in the maxillary arch. Dental casts were available on 31 patients. Dental, skeletal, and soft tissue changes were determined. The mean maxillary first molar distalization was 3.37 mm, with a distal tipping of 8.36 degrees. The mean reciprocal mesial movement of the first premolar was 2.55 mm, with a mesial tipping of 1.29 degrees. The maxillary first molar position intruded 0.1 mm, whereas the first premolar extruded 1.7 mm. The transverse width between the mesiobuccal cusps of the first molars increased 1.40 mm. The maxillary second molars were also distalized 2.27 mm, tipped distally 11.99 degrees, and moved buccally 2.33 mm. The effect of distalization on the maxillary third molars was extremely variable. The eruption of maxillary second molars had minimal effect on distalization of first molars. The lower anterior face height increased by 2.79 mm. This increase was greater in patients with higher Frankfort-mandibular plane angle measurements. The pendulum appliance is an effective and reliable method for distalizing maxillary molars, provided the anchor unit is adequately reinforced. Its major advantages are minimal dependence on patient compliance, ease of fabrication, one-time activation, adjustment of the springs if necessary to correct minor transverse and vertical molar positions, and patient-acceptance.

Adolescent↗
PubMed2002

Evaluation of maxillary molar distalization with the distal jet: a comparison with other contemporary methods.

Maxillary molar distalization is an increasingly popular option for the resolution of Class II malocclusions. This communication describes the effects of one particular molar distalizing appliance, the distal jet, in a sample of 20 consecutively treated and growing subjects (11 females, nine males; mean starting age of 13) and compares these effects with those of similar devices. Pre- and postdistalization cephalometric radiographs and dental models were analyzed to determine the dental and skeletal effects. The distal jet appliances were constructed using a biomechanical couple to direct the distalizing force to the level of the maxillary first molar's center of resistance. The distal jet was the only appliance used during the distalization phase of treatment. Examination of the cephalometric tracings demonstrated that the crowns of the maxillary first molars were distalized an average of 3.2 mm into a Class I molar relationship. In the process, the first molars were tipped distally an average of 3.1 degrees, however, the amount of tipping in each case was influenced by the state of eruption of the second molar. In subjects whose second molars had erupted only to the level of the apical third of the first molar roots, distal tipping was almost twice that seen when the second molar had completed their eruption. Anchorage loss measured at the first premolars averaged 1.3 mm, but the crowns tipped 3.1 degrees distally because of the design of the appliance. The maxillary incisors were proclined an average of 0.6 degrees with minimal effect on the mandibular plane angle and lower facial height. This study suggests that the distal jet appliance effectively moves the maxillary molars distally into a Class I molar relationship with minimal distal tipping, however, some loss of anchorage is to be expected during this process. The distal jet appliance compares favorably with other intraoral distalization devices and with mechanics featuring mandibular protraction for the resolution of patients with Class II, despite the fact that these types of mechanics address different jaws.

Adolescent↗
PubMed1987

The effect of plaque control and root debridement in molar teeth.

The healing response of non-molar sites, molar flat surface sites, and molar furcation sites was investigated in 19 adult periodontitis patients following a periodontal therapy of plaque control and root debridement. A total of 2472 sites were monitored by recordings of dental plaque, bleeding on probing, probing depth, and probing attachment levels every 3rd month for 24 months. The results demonstrated that in sites with initial probing depth of 4.0 mm or greater, molar furcation sites responded less favorably to the therapy as compared to molar flat surface sites or non-molar sites. This was demonstrated by higher mean scores for bleeding on probing, less reduction in probing depth, and a mean loss of probing attachment of 0.5 mm over 24 months. Site analyses using linear regression showed a higher % of deeper sites with probing attachment loss for the molar furcations than either molar flat surface or non-molar sites. Among sites initially 7.0 mm or deeper, 21% of molar furcations were identified as showing probing attachment loss as compared to 7% of the molar flat surface sites and 11% of the non-molar sites.

Adult↗
PubMed2005

Natural history of treatment outcomes of permanent first molars: a study of sealant effectiveness.

BACKGROUND: Few studies have used insurance claims data to retrospectively assess the natural history--a natural process or flow of events without any special interventions--and treatment outcomes of teeth with dental sealants. METHODS: The authors constructed treatment outcome trees (TOTs) from the Iowa Medicaid claims and eligibility data (1996-2000) of continuously enrolled 6-year-old children who routinely used Medicaid dental services. The authors used the TOTs to compare the restorative treatments of sealed permanent first molars with those of nonsealed permanent first molars. RESULTS: Forty percent of routine utilizers received a sealant during the four-year period. Overall, 25 percent of molars received at least one restoration. Sealed molars were less likely to receive further restorative treatment than were nonsealed molars (13 versus 29 percent). Sealed molars had fewer extensive restorative treatments (crowns, endodontic therapy and extractions) than did nonsealed molars. The median time to restorative treatment of the sealed molars also was greater than that of the nonsealed molars. All four first molars had comparatively similar patterns of subsequent care. CONCLUSIONS: Permanent first molars with sealants received less subsequent restorative treatment than did those without sealants. TOTs are useful tools for identifying necessary outcome information needed for program evaluations. CLINICAL IMPLICATIONS: Greater use of sealants could reduce the need for subsequent treatment and prolong the time until treatment may be necessary for permanent first molars.

Child↗
PubMedDate not supplied

Prevalence of cheese molars in eleven-year-old Dutch children.

In the Netherlands, first permanent molars with idiopathic enamel disturbances (IED) are called cheese molars. Though concern is expressed about their prevalence, adequate figures on the subject are missing. The porous enamel of cheese molars can be very sensitive to cold air and can decay rapidly. The aim of the present study was to investigate the prevalence in eleven-year-old Dutch children of cheese molars (IED). During an epidemiological study performed in four cities in the Netherlands, the first permanent molars and central incisors of eleven-year-old children were examined for hypoplasia, opacities, posteruptive enamel loss, premature extraction, and atypical restorations. The observation of a hypoplasia excluded the possibility of cheese molar. A total of 497 children were examined. Six percent (n = 128) of the molars (n = 1988) showed signs of IED (cheese molars), 10 percent of the children had cheese molars of which 8 percent two or more. Incisors (4 percent) with opacities were found in 3 percent in combination with two or more cheese molars. Among the four cities, no significant differences in occurrence were found. The results of this study showed that in 10 percent of the Dutch children eleven years of age, cheese molars (IED) were found. The cause for the phenomenon called cheese molars appears to be child centered. Further studies on prevalence, causes and prevention are mandatory.

Chi-Square Distribution↗
PubMed2002

Effect of in utero and lactational 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure on rat molar development: the role of exposure time.

We have previously shown that tooth development is a sensitive endpoint of dioxin toxicity. In the present study we determined the critical window of sensitivity for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced toxicity for the development of rat molar teeth. Dams were exposed to 1 microg/kg once over a time range covering the development of each molar tooth. A cross-fostering study also was conducted. Pups were killed at the age of 40 days. Erupted molars were observed by stereomicroscopy. The jaws were radiographed, the presence of molars assessed from the radiographs, and the molars measured. Pups exposed both in utero and via lactation lacked third molars and the frequency of missing molars was greater the earlier the dam was exposed: 100, 88, and 50% of the offspring exposed on gestation day (GD) 11, GD13, and GD19, respectively. All third molars developed in offspring of dams exposed on postnatal day (PND) 0, PND2, or PND4. None of the exposed pups lacked the first or the second molars. In the cross-foster study, 32 and 4% of offspring exposed only in utero and only via lactation, respectively, lacked molars. TCDD accelerated the eruption of the lower incisors and retarded the eruption of the third molars. The most critical window of sensitivity for the development of the third molar was during the early morphogenesis, from tooth initiation to the early bud stage, after which the sensitivity substantially decreased. Response to TCDD was increased if the exposure was started several days before this critical window of sensitivity or if it was continued thereafter. Dental epithelium is the likely target of TCDD.

Abnormalities, Drug-Induced↗