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At least 541 records · Page 30Linked to original sources
PubMed2006

First molar eruption related to plaque acidogenicity in children of different socio-economic status.

OBJECTIVE: The aim of this study was to evaluate the association between the eruption stage of the lower first permanent molar and dental plaque acidogenicity. Socio-economic status (SES), gender, and oral hygiene condition were also variables considered. MATERIAL AND METHODS: 230 children between 6 and 8 years of age were recruited from one public and one private primary school with different SES in Lima, Peru. Clinical examinations were performed to assess lower first permanent molar eruption stage, plaque acidogenicity, and oral hygiene condition. Bivariate associations were analyzed through chi-square tests and the variable interactions were analyzed through a hierarchical log-linear analysis with backward elimination. RESULTS: 21.8% of the population had highly acidogenic plaque, 34.3% acidogenic plaque, and 43.9% non-acidogenic plaque. Of the lower first permanent molars, 46.1% were fully erupted, whereas 53.9% were partially erupted. According to the final log-linear model, children with fully erupted molars and non-acidogenic plaque are less frequent in low than in high SES. Also, the frequency of children with partially erupted molars and acidogenic to highly acidogenic plaque is higher in males than in females. Finally, fully erupted molars and non-acidogenic plaque are more frequent in children with good hygiene than in children with moderate to poor hygiene. CONCLUSIONS: Association between eruption stage of the lower first permanent molar and plaque acidogenicity was not significant in a bivariate context. However, in a multivariate context, socio-economic status, oral hygiene condition, and gender had an impact on the association between the two main variables.

Acids↗
PubMed1999

The effects of sandblasting on the bond strength of molar attachments--an in vitro study.

This study evaluated the effect of sandblasting foil mesh molar tube bases on the shear bond strength obtained when bonding to first molar teeth. Fifty-two recently extracted first molar teeth were etched with 35 per cent phosphoric acid gel for 30 seconds. Twenty-six sandblasted 'A' Company molar tube attachments and 26 non-sandblasted attachments were then bonded to the teeth using Phase II orthodontic bonding resin. After storage in water for 24 hours at 37 degrees C, the specimens were debonded in a direction parallel to the buccal surface. Survival analysis using the Weibull function revealed that for a 90 per cent probability of survival, the predicted bond strengths for sandblasted and non-sandblasted bases were 1.76 and 1.66 MPa, respectively. For larger shear stresses, the probabilities of bond survival with sandblasted molar tubes were greater than with non-sandblasted molar tubes although the differences were small, which may be explained by the large proportion of bond failures which occurred at the resin to enamel interface in both groups. It was concluded that sandblasting foil mesh bases is likely to provide only a minimal improvement in clinical performance when bonding to molar teeth.

Dental Bonding↗
PubMed2000

A comparative analysis of distal maxillary molar movement produced by a new lingual intra-arch Ni-Ti coil appliance and a magnetic appliance.

The aim of the study was to evaluate cephalometrically the dental and skeletal treatment effects of a new lingual intra-arch Ni-Ti coil appliance for molar distalization and to compare these with those of an established intra-arch appliance that uses repelling magnets for distal molar movement. Two groups of 21 adolescents, all girls, participated in this retrospective study. One group was treated with the new lingual Ni-Ti coil appliance for 6.5 months and the other with the magnetic appliance for 5.8 months. The treatment effects were analysed by measurements on lateral head radiographs at the start of treatment and after the molar distalization was completed. The mean amount of distal molar movement was 2.5 mm (SD 0.69) in the lingual coil group and 2.6 mm (SD 0.51) in the magnet group. A significantly higher degree of distal molar tipping was found in the magnet group, -8.8 degrees, compared with -2.2 degrees for the lingual coil group. Due to anchorage loss, the maxillary incisors moved forwards, and the overjet was increased by an average of 1.2 mm in the lingual coil group and 1.7 mm in the magnet group. The results indicate that the new lingual Ni-Ti coil appliance was better choice than the magnet appliance for distal bodily movement of maxillary molars. The benefits of the new Ni-Ti appliance were due to the design preventing molar tipping and its single activation.

Adolescent↗
PubMed2002

Analysis of quantitative trait locus effects on the size and shape of mandibular molars in mice.

While >50 genes have been found to influence the development of teeth in mice, we still know very little about the genetic basis for the adaptive characteristics of teeth, such as size and shape. We applied interval mapping procedures to Procrustes size and shape data obtained from 10 morphological landmarks on the mandibular molar row of the F(2) progeny from a cross between the LG/J and SM/J strains of mice. This revealed many more QTL for molar shape (18) than for molar centroid size (3), although levels of dominance effects were comparable among QTL for size and shape. Comparisons of patterns of Procrustes additive and dominance shape effects and ordination of QTL effects by principal components analysis suggested that the effects of the shape QTL were dispersed among the three molars and thus that none of these molars represents a genetically distinct developmental structure. The results of an analysis of co-occurrence of QTL for molar shape, mandible shape, and cranial dimensions in these mice suggested that many of the QTL for molar shape may be the same as those affecting these other sets of characters, although in some cases this could be due to effects of closely linked genes.

Animals↗
PubMed2002

Unilateral distalization of a maxillary molar with sliding mechanics: a case report.

INTRODUCTION: A unilateral Class II relationship could arise due to early loss of an upper second deciduous molar on one side during the mixed dentition period. This would allow the mesial drift of the molars, which may block the eruption of the second premolar. METHODS AND RESULTS: A 15-year 8-month-old male patient presented with a Class II molar relationship on the right, and Class I canine and molar relationship on the left side. His E was extracted when he was 5 years old. The 54 were impacted and the 3 was ectopically positioned due to the space loss from the mesial migration of the 76. In addition 21 1 were in cross-bite. Skeletally he had Class III tendency with low MMPA. He presented with a straight profile and retruded upper lip. For maxillary molar distalization, a newly developed 'Keles Slider' was used. The appliance was composed of one premolar and two molar bands, and the anchorage unit was composed of a wide Nance button. 46 were connected to the Nance button and, therefore, included into the anchorage unit. The point of distal force application was close to the centre of resistance of the 6 and parallel to the occlusal plane. Ni-Ti coil springs were used and 200 g of distal force was applied. Seven months later the space required for eruption of the permanent premolars and canine was regained, and the anterior cross-bite corrected. The appliance was removed and final alignment of the teeth was achieved with fixed appliances. CONCLUSION: At the end of the second phase treatment Class I molar and canine relationship was achieved on the both sides, the anterior cross-bite was corrected, inter-incisal angle was improved, and ideal overbite and overjet relationship was achieved. The active treatment time was 27 months.

Adolescent↗
PubMed2002

Clinical investigation of second mesiobuccal canals in endodontically treated and retreated maxillary molars.

An examination of 1873 conventionally treated and retreated maxillary first and second molars was made in an attempt to determine the percentage of second mesiobuccal (MB2) canals that could be located routinely and evaluate if there were any significant differences between initial treatments and retreatments. The teeth examined were 1193 first molars and 680 second molars treated consecutively over a 2-yr period by five endodontists. Overall the MB2 canal was found in 724 (61%) first molars and 245 (36%) second molars. The incidence of a MB2 canal in first molar retreatments was 67% compared to a 59% incidence in initial treatments. Whereas in second molars, the retreatment incidence was 44% compared with 35% in initial treatments. The significant difference in the incidence of a MB2 canal between initial treatments and retreatments suggests that failure to find and treat existing MB2 canals will decrease the long-term prognosis.

Chi-Square Distribution↗
PubMed2005

A 5 yr clinical investigation of second mesiobuccal canals in endodontically treated and retreated maxillary molars.

An examination of 5616 endodontically treated and retreated maxillary first and second molars was made in an attempt to determine the percentage of MB2 canals that could be located routinely, and evaluate if there were any significant differences between initial treatments and retreatments. The teeth examined were 3578 first molars and 2038 second molars treated consecutively over a 5-yr period by six endodontists. Overall the MB2 canal was found in 2133 (60%) first molars, and 712 (35%) second molars. The incidence of a MB2 canal in first molar retreatments was 66% compared to a 58% incidence in initial treatments. Whereas in second molars the retreatment incidence was 40% compared to 34% in initial treatments. The significant difference in the incidence of a MB2 canal between initial treatments and retreatments suggests that failure to find and treat existing MB2 canals will decrease the long-term prognosis.

Chi-Square Distribution↗
PubMed2005

The effect of an early Le Fort III surgery on permanent molar eruption.

The purpose of this retrospective study was to evaluate the extent to which an early Le Fort III osteotomy affects the position and eruption of the permanent maxillary first and second molars. To test the null hypothesis that there are no changes in eruption patterns, 31 patients diagnosed with craniosynostoses (13 with Crouzon's syndrome, nine with Apert's syndrome, eight with Pfeiffer's syndrome, and one with Carpenter's syndrome) with a mean age at the time of surgery of 5.3 +/- 1.3 years were studied. All patients underwent a Le Fort III osteotomy performed by a single surgeon to correct the anatomical deformity for functional and psychosocial reasons. Eighteen patients with craniosynostoses who had not been operated on (11 with Crouzon's syndrome, four with Apert's syndrome, and three with Pfeiffer's syndrome) served as controls; they had a mean age of 21.2 +/- 9.5 years. First and second molar positions and eruption patterns were assessed separately on panoramic radiographs by three observers. For the patients who underwent surgery, long-term evaluation showed that although 79 percent of all first molars erupted compared with 100 percent for the control group (p < 0.001), only 18 percent of all second permanent molars erupted compared with 89 percent for the control group (p < 0.0001). The authors conclude that in a significant minority of cases, early Le Fort III osteotomy affects first molar eruption, whereas the probability of second molar eruption is significantly decreased in the majority of cases. Therefore, Le Fort III osteotomy sites should be positioned distal to the second molar tooth buds. If this is not possible, patients, parents, and dental professionals should be made aware of these early postosteotomy sequelae so that later treatment planning can be enhanced.

Adult↗
PubMed1987

Attachment loss in primary molars.

The view that primary teeth are only rarely affected by periodontitis has been generally adopted. The aim of the present work was to measure attachment loss and to establish its prevalence, severity and distribution in stained, extracted primary molars. The material consisted of 4 groups of 50 teeth each: first and second upper and first and second lower primary molars. Teeth were selected to fulfil 2 criteria: (1) a carious cavity not extending beyond the cemento-enamel junction and involving only 1 of the proximal surfaces, the other 3 surfaces being sound; (2) root resorption, if present, not affecting more than the apical third of the roots. The teeth were stained in 1% aqueous crystal violet and examined under a stereomicroscope fitted with an ocular micrometer. The distance between the cemento-enamel junction and the most coronal attachment fibres was measured in the mid-line of each surface. Attachment loss was found in 94% of the teeth and on 2/3 of the surfaces. This indicates that periodontitis in primary teeth is not a rare phenomenon. The mean loss of attachment was 0.26 +/- 0.32 mm, which cannot be regarded as clinically important. The maxillary molars and the first molars, and, the proximal surfaces showed more loss of attachment than did the mandibular molars and the second molars, and the buccal and lingual surfaces taken together. This pattern of attachment loss is similar to that seen in permanent molars. On the carious proximal surfaces, significantly more attachment loss was noted than on the sound proximal surfaces.

Connective Tissue↗
PubMed1980

Caries susceptibility of permanent first and second molars in children aged 5-15 years.

Clinical examinations of 276 5-year-old children were carried out twice yearly for 2 1/2 years, and a further 1104 11--12-year-old children were examined annually for 3 years. Fifty per cent of permanent first molar teeth had erupted by 6.4 years; the mean age of eruption for permanent second molar teeth was 12.2 years. One year after these mean eruption dates over 10% of first molars and 45% of second permanent molars were already carious. Although development of caries was initially slower in permanent first molars, between the ages of 7.5 and 8.5 years the caries increment rose to 18.8%. By the age of 15 years the DMF was 92% for first and 68% for second molar teeth. The missing and filled proportion of the total DMF rose consistently. This represents the amount of treated caries and exceeded the amount of untreated caries in permanent first molars at all age levels. The rate of caries initiation in the present investigation emphasizes that restorative programmes and preventive regimens for children must be based on frequent recall examinations of not more than 6-monthly intervals.

Adolescent↗
PubMed1992

General dental practitioners' evaluation of the need for extraction of asymptomatic mandibular third molars.

Thirty general dental practitioners were asked to evaluate the need for extraction of asymptomatic mandibular third molars. Thirty-six mandibular third molars with equal distribution of angular positions, impaction status, males and females and age groups were selected. To estimate the consistency of the evaluation, the 36 cases were duplicated so that, in all, 72 teeth were evaluated. The number of molars proposed to be extracted by the observers varied from 0 to 26. There was no third molar which all observers agreed should be extracted. The two molars which most observers, 25 and 23 of altogether 30 observers, proposed to be extracted were partially covered by soft tissue. The decision not to extract two molars was unanimous. Both of these were completely covered by bone tissue and positioned vertically. The mean overall intra-observer agreement for the therapeutical decision was 92%, with a range of 69-100%. The length of professional experience of the observer did not influence the evaluation whether or not to extract. We conclude that there is a great variation among general dental practitioners regarding their evaluation on the need for removal of asymptomatic mandibular third molars.

Adult↗
PubMed1992

Odontogenic lesions in opercula of permanent molars delayed in eruption.

Opercula of permanent first and second molars delayed in eruption were investigated histologically to detect possible causes of eruption failure. The material comprised operation specimens from exposure of 74 non-erupted molars in 63 young individuals (34 boys, 29 girls). Eighteen of the 74 specimens (or 24.3%) were diagnosed as "classical" odontogenic tumors belonging to the following entities: ameloblastic fibroma (seven), ameloblastic fibrodentinoma (six), ameloblastic fibro-odontoma (four) and complex odontoma (one). Twenty-two specimens (or 29.7%) showed a hitherto unrecognized odontogenic lesion of hamartomatous character, termed odontogenic giant cell fibromatosis (OGCF). Thus, 54.1% of the specimens could be diagnosed as odontogenic tumors or hamartomas. Histomorphologic changes could not be detected in the remaining 34 specimens (45.9%). Odontogenic tumors were associated with unerupted first molars much more frequently than with second molars (ratio 8:1). The OGCF had a strong association with unerupted mandibular molars. Further, opercula of mandibular first molars frequently revealed odontogenic lesions whereas tissue overlying the crown of unerupted maxillary second molars often was reported as normal operculum.

Adolescent↗
PubMed1995

Morphologic criteria for root canal treatment of primary molars undergoing resorption.

The endodontic anatomy of primary molars is difficult to predict because of the balance of resorption and hard tissue deposition. In particular, the resorption causes perforating lacunae across the wall of the root, even at the furcation level, and modifies shape, dimension and position of endodontic apex. The phenomenon can be so deep as to compromise endodontic therapy. The first aim of the study was to verify if reliable criteria can be found for treatability in primary molars undergoing resorption, i.e. if it is possible to predict if perforating lacunae are present or not. The second aim of the study was to verify if other informations needed for endodontic treatment, as shape, dimension and location of the apex, and curvature of the root canal can be predicted. For the study, 80 extracted primary molars, 75 of which pulpally involved by caries, were selected. The treatability was evaluated in term of root length, root shape, dimension and shape of endodontic apex, age of the patient and X-ray index of resorption. The association between variables was performed by multiple correspondence analysis. The results suggested that root length was the most reliable criterion of the integrity of the root. The borderline of treatability was at the length of 4 mm. The position of endodontic apex related to anatomical apex, and the lingual related to the buccal root length were analyzed by linear regression analysis. The canal length was often similar to the root length (i.e. the endo and anatomical apices were very close) in lower and upper molars. However, in lower molars, if two or more canals were present in the same root, a discrepancy was observed between buccal and lingual root length. This finding was constant in first lower molars. In addition regression analysis provided a linear function between the lengths of the buccal and lingual side of the same root in lower molars. Its coefficient b was 0.73.

Analysis of Variance↗
PubMed1988

Wear of composite resin restorations in primary versus permanent molar teeth.

The purpose of this investigation was to compare the wear rates of posterior composite resin restorations in primary versus permanent teeth. Based on theories of composite wear in primary molars, as well as on empirical observations, we hypothesized that wear would be greater in permanent tooth restorations. In Part I of the study, quantitative wear data from four different clinical trials (three permanent tooth studies and one primary tooth study) were compared. The same posterior composite restorative material was investigated in each of the four studies. In Part II of the study, quantitative wear data were drawn from a single clinical trial wherein the same experimental posterior composite material was placed in primary and permanent molars in the same children. In Part II, the baseline sample size included posterior composite restorations placed in 92 primary and 95 permanent molars in all children (ages 7-10). Quantitative wear data were obtained by the cast assessment method at baseline, six, 12, and 24 months. The 24-month sample size was based on 48 available primary molar restorations and 89 permanent molar restorations. The loss of primary restorations was due almost exclusively to natural exfoliations. Findings in Part I revealed no significant difference in the wear of primary versus permanent molar restorations. In Part II, wear findings for primary molar versus permanent teeth, respectively, were as follows (in micrometers): 47 versus 49 at six months; 86 versus 80 at 12 months; and 133 versus 131 at 24 months. With a Wilcoxon two-sample test and an alpha level of 0.05, there were no significant differences at any recall for the wear rate of primary versus permanent restorations. These results differ sharply from findings reported by others.

Child↗
PubMed1989

In vitro effects of calcitonin and/or parathyroid hormone on odontogenesis of mouse embryonic molars.

Mandibular first molars of mouse embryos were cultivated for examination of the effects of calcitonin (CT) and/or parathyroid hormone (PTH) on the odontogenesis of the molars, and for determination of whether and how CT, which is a PTH antagonist, has an influence on the effect of PTH on odontogenesis. On the second day, the inner enamel epithelium in the control group had already differentiated into pre-ameloblasts. Typical odontoblasts had secreted a layer of predentin. On the fourth day of culture, the pre-ameloblasts achieved terminal differentiation into secretory ameloblasts, and enamel and dentin had already been deposited. PTH (1 unit/mL) inhibited the odontogenesis of the cultured molars during the designated culture periods (two and four days), while CT (0.5 unit/mL) stimulated odontogenesis. On the second day, the development of the molars in the CT + PTH group showed an intermediate stage between the control and PTH-treated explants, but on day 4 it corresponded to that of the controls. Moreover, when the molars exposed to PTH for two days were untreated and treated with CT for an additional two days, the former produced a small quantity of enamel matrix, while the latter formed a large amount of the matrix. These histological findings were also supported by a morphometric analysis of the enamel matrix in the cultured molars. The present results suggest that CT stimulates, but PTH suppresses, the odontogenesis of the mouse embryonic molars, and that CT is an antagonist to the inhibitory effect of PTH on odontogenesis.

Amelogenesis↗
PubMed2005

Clinical evaluation of the effects of radiographic distortion on the position and classification of mandibular third molars.

OBJECTIVE: Panoramic radiographs are routinely employed for surgical planning of unerupted third molars. The objective of this study was to evaluate distortions in the position of mandibular third molars on panoramic radiographs. MATERIALS AND METHODS: Panoramic radiographs of 14 patients with indication for extraction of the mandibular third molars were used. Transurgical impressions of the crowns of the teeth to be extracted and adjacent second molars (n=19) were achieved with addition silicone and poured with type IV plaster for comparison of the inclinations of the third molars on the radiographs and study casts. RESULTS: There was a mean difference of -5.37 degrees between the position of the third molar on the panoramic radiograph and on the study cast (standard deviation 1.46, P<0.05, Student's t-test). CONCLUSION: There is distortion in the position of teeth on the panoramic radiograph, which may influence the surgical planning; however, this does not invalidate it as the main tool for diagnosis and surgical planning of mandibular third molars.

Artifacts↗
PubMed1987

Sensory innervation of the periodontal ligament in the incisor and molar of the monkey, Macaca fuscata. An immunohistochemical study for neurofilament protein and glia-specific S-100 protein.

Nervous elements in the periodontal ligament of the monkey, Macaca fuscata were investigated by means of immunohistochemistry for neurofilament protein (NFP) and S-100 protein. Thick nerve bundles with NFP-immunoreactivity entered the periodontal ligament through slits at the bottom of the alveolar socket, whereas thinner bundles, also NFP-immunoreactive, penetrated the ligament from the lateral wall of the alveolar socket. The NFP-immunopositive nerve fibers were densely distributed around the root apex in both incisors and molars. In the upper incisors, another dense distribution of NFP-positive nerves was found in the apical half of the lingual periodontal ligament and in the coronal half of the labial periodontal ligament. The periodontal nerve fibers in the incisors ramified in a dendritic fashion, terminating as free nerve endings within the periodontal ligament. Immunostaining for S-100 protein demonstrated the Schwann sheaths of nerves which showed the same distribution pattern as that of the NFP-immunopositive fibers in the periodontal ligament of the incisors. In molars, immunostaining for NFP and S-100 showed that nerves were numerous in the apical region of the periodontal ligament. However, NFP-immunopositive nerves were fewer than the S-100-positive nervous elements in the apical region in molars. This discrepancy suggests the presence of NFP-immunonegative nerves. Immunostaining for S-100 is thus useful for demonstration of neural elements in the periodontal ligament of molars. The S-100-immunoreactive neural elements in the periodontal ligament were more numerous in incisors than in molars. In addition to the free nerve endings, a small population of coiled nerve endings was observed in the periodontal ligament of molars. Most of the nerve fibers and cell bodies in the trigeminal ganglion showed NFP-immunoreactivity, whereas all in the mesencephalic nucleus of the trigeminal nerve were negative in NFP-reaction. This finding suggests that the periodontal ligament of molars receives a dual innervation from the trigeminal ganglion and mesencephalic nucleus.

Animals↗
PubMed1984

Molar and nonmolar teeth compared over 6 1/2 years following two methods of periodontal therapy.

Limited information is available comparing the relative longitudinal effectiveness with respect to tooth type of scaling and root planing alone and scaling and root planing followed by flap procedures. The purpose of this study was to investigate these treatment methods as applied to molar and nonmolar teeth on a longitudinal basis in humans. Seventeen subjects with chronic periodontitis received thorough scaling and root planning as well as oral hygiene instruction. A modified Widman flap was then randomly performed for one-half of each subject's dentition. Routine recall prophylaxis and oral hygiene reinforcement were administered postsurgically every 3 to 4 months. Pocket depth and clinical attachment levels were recorded by a single calibrated examiner before therapy and at intervals up to 61/2 years following active treatment. Ten subjects remained as participants after 61/2 years. A paired t test was used to test for the mean difference in pocket depth and clinical attachment level between molar and nonmolar teeth for each treatment method. For pockets initially 4 to 6 mm, the results indicated greater pocket depth and more apical clinical attachment level on molars than nonmolars treated by either method of therapy. For pockets initially greater than or equal to 7 mm there was no difference between pocket depth on molar and nonmolar teeth following scaling and root planing alone. However, there was less overall pocket depth on nonmolars than molars following the flap procedure, indicating a greater effect of pocket reduction on nonmolar than molar teeth with the flap procedure. No difference between tooth types was found for clinical attachment level in pockets initially greater than or equal to 7 mm with either treatment method. Both treatment methods resulted in at least maintenance of pretreatment attachment levels adjacent to molar and nonmolar teeth.

Adult↗