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PubMed2005

Roots of the maxillary first and second molars in horizontal relation to alveolar cortical plates and maxillary sinus: computed tomography assessment for infection spread.

The purposes of this study were to investigate the horizontal relationship of the roots of maxillary molars with the cortical plates and the maxillary sinus and to investigate the influence of these relationships on the spread of odontogenic infection. Computed tomography images of 120 control subjects and 49 patients with infection originating in the maxillary first or second molar were investigated. In the control group, more than 60% of the first molar roots contacted both palatal and buccal cortical plates (type A), while such contact was not seen in more than 60% of second molars. The floor of maxillary sinus was most frequently observed at the level between the bifurcation and apices of roots in both first and second molars. In patients with infection, cortical changes were more frequently seen on the buccal side than on the palatal side, and 80% of patients with buccal cortical change showed the position in which the buccal roots were close to the buccal cortical plate. Mucosal thickening of the maxillary sinus was found in 87.8%. The buccopalatal spread of odontogenic infection originating in the maxillary first and second molars was influenced by the horizontal root position in relation to the cortices.

Adolescent↗
PubMed2006

Comparison of dynamic shear properties of the porcine molar and incisor periodontal ligament.

The role of the periodontal ligament (PDL) is to support the tooth during function and resist external forces applied to it. The dominant vertical component of these forces is associated with shear in the PDL. The mechanical response to vertical force may, however, be different between the molar and incisor as their loading regimen is different. The present study was designed to determine the viscoelastic behavior in shear of the PDL of the porcine molar and incisor (n = 10 for each). From dissected mandibles transverse sections including the mesial root of first molar and the incisal root were obtained and used for dynamic shear tests. Shear strain of 1.0% was applied in superoinferior direction parallel to the root axis with a wide range of frequencies (0.01-100 Hz). The viscoelastic behavior was characterized by the storage and loss modulus and loss tangent as a function of the frequency. For the incisor and molar, the complex and storage moduli increased significantly with the frequency. For the incisor, the loss modulus also increased with the frequency. The loss modulus and loss tangent were significantly (p < 0.05) larger in the incisor than in the molar. The present results suggest that the incisal PDL revealed more viscous behavior during dynamic shear than the molar one, which might have important implications for the principal role of the anterior teeth such as PDL sensation.

Animals↗
PubMed1982

Molar occlusion and mandibular rotation: a longitudinal study.

The human dentition undergoes a process of complex development. Growth of the skeleton, morphology and function of the soft tissues (muscles in particular and airway), space considerations, and other factors influence the development of the dentition. The present study considered two of the factors involved: molar relationship in the sagittal plane and mandibular rotation. Forty-two persons from the Burlington sample were studied to determine whether changes in molar relation between the mean of ages 7 to 12 years were correlated with the rotational growth pattern of the mandible. The sample was divided into forward rotators (FR) and backward rotators (BR), based on the changes in the SN-corpus axis angle over time. The statistically significant difference of 4.04 degrees in change of the SN-CA angle over time, between the FRs and BRs, indicates that this method of characterizing the two different types of growers is useful. It is interesting to note, however, that the FRs and BRs, on an average, initially had the same SN-corpus axis angles. The molar relationship was determined on the basis of the cusp-fossa relationship in the sagittal plane. In the twenty-eight forward rotators and fourteen backward rotators the molar relationship did not change in a predictable fashion. Statistically significant correlations were not found between molar occlusion and growth direction patterns. Also, the SN-corpus-axis angle, at a single point in time, is not a good predictor of whether an individual is going to exhibit a forward or backward mandibular rotational growth pattern. The change in molar occlusion during the process of growth and development is a multifactorial phenomenon and cannot be predicted on the basis of the direction of mandibular growth rotation between the ages of 7 and 12 years.

Cephalometry↗
PubMed1985

The effect of extraction of infraoccluded deciduous molars: A longitudinal study.

Infraocclusion of deciduous molars is often associated with ankylosis. Such teeth are believed to be potential sites of malocclusion, with a risk of tipping of neighboring teeth and loss of space. Extraction has therefore been the most widely recommended treatment. The aim of this study was to follow longitudinally the effect of extraction versus nonextraction treatment in twenty-three homologous pairs of mandibular deciduous molars with infraocclusion when unilateral extraction was performed. The study comprised fifteen children with a mean age at the start of 10.1 years. Recordings were made at the start of the study and every 6 months thereafter until eruption of permanent successors. Periodic identical periapical radiographs and study models were taken every 6 months. Ten of the twenty-three mandibular deciduous molars on the nonextraction side showed progression of the degree of infraocclusion. All infraoccluded deciduous molars exfoliated within the normal time. There was a normal alveolar bone height on both sides after eruption of the successors. Extraction resulted in a gradually increasing space loss in fourteen of the fifteen children. In two cases a definite space deficiency at the time of eruption of the successors was registered. It has been possible to confirm very few of the previously reported negative effects following nontreatment of infraoccluded deciduous molars on exfoliation, eruption, and occlusal development in this study. The results favor a more conservative approach to extraction therapy of infraoccluded deciduous molars.

Adolescent↗
PubMed1991

Crevicular IgG antibodies and Streptococcus mutans on erupting human first permanent molars.

The specific IgG antibody activity against indigenous Streptococcus mutans in gingival crevicular fluid (GCF) was determined in 25, 6-7-yr-old children. Samples of plaque and GCF were collected from all erupting first permanent molars. Plaque samples were also collected from the adjacent second primary molars. The presence of clinical caries was scored as defs. In the same individual a highly significant correlation (p less than 0.005) was found between the level of specific antibody activity in GCF when comparing first permanent molars with each other. No correlation was found between the specific antibody activity in GCF and the number of indigenous Strep. mutans colonizing the buccal surfaces of the first permanent molars. Caries-free children had significantly less specific antibody activity in GCF than children with caries experience (p less than 0.05). In the same child a highly significant correlation (p less than 0.0001) was found between the level of colonization by mutans streptococci on the permanent molars and the adjacent second primary molars.

Antibodies, Bacterial↗
PubMed1992

Effects of maternal caffeine intake during lactation on molar enamel surfaces in new-born rats.

Dams were fed normal laboratory chow until delivery. At birth, the litters were combined, and eight pups were randomly assigned to each dam. Dams with the recombined litters were divided into two groups. Dams of group 1 were fed a 20% protein diet as a control; dams of group 2 were fed a 20% protein diet supplemented with caffeine (2 mg/100 g of the dam's weight). On day 22, the dams of group 2 were anaesthetized with ether. They were injected with 2 iu of oxytocin in order to collect milk. Blood was collected from pups and dams to determine its caffeine concentration. The first and second molars were removed from each pup's mandible and maxilla. Radiographs were taken of 10 randomly selected first or second molars from each group. Four randomly selected molars from each litter were placed in a specially designed chamber and bathed with a constant flow of acid solution to determine the amount of mineral dissolved from the enamel surfaces. The remaining non-acid exposed molars were pulverized in freezer mills. A small portion of this powder was then analysed for the total amount of minerals. No differences were found in the radiographic density of enamel between the groups. The amount of dissolved calcium, phosphorus and magnesium from enamel surfaces in the caffeine group was consistently greater than that of the non-caffeine group in the first molars, whereas, in the second molars, there was no difference between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Histochemical demonstration of neural carbonic anhydrase activity within the mandibular molar and incisor tooth pulps of the rat.

Carbonic anhydrase (CA) activity was enzyme histochemically assessed in: (1) neuronal cell bodies in the rat trigeminal ganglion that were retrogradely labeled with FITC-WGA from the mandibular molar and incisor tooth pulps; (2) cell bodies retrogradely labeled with HRP-WGA from the mandibular molar tooth pulp; and (3) nerve fibers within the decalcified mandibular molar and incisor tooth pulps. The cell size spectrum of the FITC-WGA-labeled neurons was similar for both molar and incisor tooth pulps with about 90% being medium or large (greater than or equal to 300 microns2 in cross-sectional area). About 30% of the FITC-WGA-labeled cell bodies exhibited CA activity for both tooth pulps. The HRP-WGA-labeled cells also showed CA activity. In the molar root pulp, finely myelinated nerve fibers exhibited CA activity. Histochemical reaction products were distributed in the axoplasm and the cytoplasmic pocket of Schwann cell inside the compact myelin. In the incisor pulp, CA-reactive unmyelinated axons coexisted with non-reactive axons within the same Schwann units. The Schwann cell cytoplasm directly surrounding reactive axons also exhibited histochemical stainability. In the light of known distribution of CA in the peripheral nervous system, the present data suggest that the rat molar and incisor tooth pulps receive substantial innervation of large myelinated primary afferent fibers. The finely myelinated and unmyelinated axons, that have been repeatedly shown to predominate the intrapulpal nerve fibers, are considered to represent intrapulpal, terminal and preterminal specialization of otherwise large myelinated nerve fibers.

Animals↗
PubMed1986

Correlation of acute pericoronitis and the position of the mandibular third molar.

Acute pericoronitis is a painful, debilitating infection that is most commonly found among young adults with erupting mandibular third molars. Prophylactic removal of third molars to prevent this disease has been advocated, but this procedure requires an accurate description of the third molar at highest risk for this infection. Clinical and radiographic measurements were compared in 25 diseased subjects and 109 normal subjects. Of 10 variables significantly related to the presence of acute pericoronitis, stepwise discriminant analysis selected 4 variables that produced a canonical correlation coefficient of 0.71. In clinical terms, these variables described the tooth at highest risk for acute pericoronitis as a fully erupted, vertical mandibular third molar that is in contact with the adjacent second molar, at or above the occlusal plane, and partially encapsulated by soft or hard tissues. Prophylactic treatment of these third molars is highly recommended.

Acute Disease↗
PubMed1986

Relationship between the apices of the lower molars and mandibular canal--a radiographic study.

The study was performed on forty-six randomly chosen dry mandibles. The molar areas of each mandible were radiographed by the paralleling technique, and an additional radiograph at -20 degrees angulation of the same area was taken. Measurements of the distance between the upper border of the mandibular canal and the root apices of the first and second molars were taken. The location of the mandibular canal in the buccolingual plane was determined. The obtained data were statistically evaluated. Statistically significant symmetry of the relationship of the mandibular canal to the root apices was established between the right and left sides of the same mandible. In the majority of cases the mandibular canal was buccal to the apices of the second molar, and in the first molar area the canal was lingual to the root apices in almost half of the cases. Most frequently, the upper border of the mandibular canal was located 3.5 to 5.4 mm below the root apices of both first and second molars. In no case was the mandibular canal found in close proximity, both in the vertical and in the buccolingual planes, to the first and second molar apices.

Adult↗
PubMed1994

Prophylactic extraction of third molars in cancer patients.

Most studies on third molar extractions focus on the potential of tooth-associated pathoses when justifying or questioning the extraction. Scant attention is paid to potential medical problems of the patient "attached" to the third molar. This study presents 28 consecutive cancer cases seen by one dentist over a 2-year period in which third molars had a significant impact on the health of the patient and on their course of cancer therapy. In 15 patients on whom extractions were performed, 40% experienced postoperative complications. Prophylactic extraction of partially erupted or impacted third molars in cancer patients before their cancer therapy is recommended on the basis of the following observations: (1) the increased risks and difficulties associated with post-cancer-treatment extraction, (2) the potential for third molars to produce pathoses in immunocompromised patients before, during, or immediately after their anticancer treatment, and (3) the management of third molars may interfere with the patient's cancer treatment.

Adolescent↗
PubMed1991

Clinical, radiographic and histological characteristics of secondary retention of permanent molars.

Secondary retention refers to the cessation of eruption of a tooth after emergence neither due to a physical barrier in the path of eruption nor as a result of an abnormal position. In this study, the clinical and radiographic features of 81 secondary retained permanent molars in a group of 53 patients were evaluated. Retained molars removed for therapeutic reasons (n = 38) were examined histologically to detect any areas of ankylosis. The first molars in the mandible and maxilla were most frequently affected. The mean infraocclusion at the patients' first visit was 4.3 +/- 1.9 mm. After 6 months, infraocclusion increased in adolescents but was stable in adults. Tilting of the adjacent teeth was observed in 39 cases. A sharp, solid percussion sound and a partial absence of the periodontal ligament space on radiographs were noted in less than one-fifth of the affected molars, while histological evaluation revealed that local areas of ankylosis were present in all cases. From the data relating to the 38 molars removed for therapeutic reasons, the sensitivity of the percussion test and radiographic evaluation was found to be 29 and 21 per cent respectively. During a period of 4 years, six new cases of secondary retention were observed in the same population. From this study it is concluded that secondary retention of permanent molars seems to be associated with focal ankylosis and that percussion tests and radiographs are not sufficiently reliable to exclude the presence of ankylotic areas. The presence of ankylotic areas and tendency of infraocclusion to increase in adolescents but to be stable in adults have major implications for therapy.

Adolescent↗
PubMed1995

Age estimation from the permanent molar in northeast China by the method of average stage of attrition.

A new method of age estimation using permanent molars, the method of average stage of attrition (ASA), is described. A total of 633 molars, including the first molar (M1) and the second molar (M2) on both jaws, was collected from 57 cadavers and 54 modern dry skulls in northeast China. The attrition condition of the molar crown was analyzed, and a new graduation standard was established. Six linear equations for age estimation were obtained by means of regression analysis. The ASA method gave an estimated age at death from only one molar, either M1 or M2, on either maxilla or mandible. The maximum error of these equations was 4.53 years. The results show that the ASA method can or does reflect the attrition condition of the whole occlusal surface more objectively than some methods using dental wear because the wear degree is estimated by averaging the wear stages of all the cusps rather than of only one or partial cusps.

Adolescent↗
PubMed2006

Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system.

INTRODUCTION: It is now possible to predictably move maxillary molars distally in nongrowing patients with the skeletal anchorage system (SAS) and to improve malocclusions without having to extract the premolars and regardless of the patient's compliance. The purposes of this study were to investigate the amount of distal movement of the maxillary first molars, the type of movement, the difference between actual and predicted amounts of distalization, and the relationship between the amount of distalization and age. METHODS: Twenty-five nongrowing patients (22 female, 3 male) successfully treated with the SAS were the subjects in this study. The amount and the type of distalization, the difference between predicted and resulting amounts of distalization, and the relationship between the patient's age and the amount of distalization were analyzed with wide-opening cephalometric radiographs. RESULTS: The average amount of distalization of the maxillary first molars was 3.78 mm at the crown level and 3.20 mm at the root level. The amount of distalization at the crown level was significantly correlated with the average value of treatment goals (3.60 mm). CONCLUSIONS: The maxillary molars were predictably distalized in accordance with the individualized treatment goals without regard to patient age and extraction of the third or second molars. The SAS is a viable noncompliance modality to move maxillary molars for distally correcting maxillary protrusions and malocclusions characterized by maxillary incisor crowding.

Adolescent↗
PubMed2006

Scanning electron microscopy of the three different types of cementum in the molar teeth of the guinea pig.

The aim of this study was to observe the three-dimensional distribution and structural characteristics of the three different types of cementum in the molar teeth of guinea pig by means of scanning electron microscopy. Twenty-five 4-week-old male guinea pigs were used in this study. Using decalcified and undecalcified specimens with or without NaOH maceration, we examined the mandibles, maxillae and extracted molars by scanning electron microscopy. Guinea pig molars consist of two longitudinal, deeply folded lamina cores covered by enamel on all surfaces, except the buccal surface of the upper molars and the lingual surface of the lower molars. In the regions without enamel, we observed continuous thin belt-like layers of conventional acellular cementum on the dentin surface. On the enamel-covered surfaces, two different types of coronal cementum were found: small circular islands of coronal cementum called cementum pearls, which were distributed widely at almost regular intervals on the peripheral enamel surface from the apical fifth to the occlusal surface; and cartilage-like cementum, which occupied almost all of the occlusal half of the two longitudinally folded grooves. The present study demonstrated the unique distribution pattern of the three different types of cementum in guinea pig molars. These cementum types may contribute to the requirements for many different functions such as mastication, anchorage and continuous tooth eruption.

Animals↗
PubMed2006

Peripherin- and CGRP-immunoreactive nerve fibers in rat molars have different locations and developmental timing.

UNLABELLED: Developing rat molars gain mature sensitivity to electric stimulation at 4-5 weeks after eruption, but the related mechanisms are incompletely understood. Preliminary studies showed weak co-localization of calcitonin gene-related peptide (CGRP) immunoreactivity (IR) with peripherin (PER) or neurofilament protein (NF) in rat molar nerve fibers, while the latter two co-localized extensively. OBJECTIVE: Our goal was to compare timing and location of PER-IR and CGRP-IR innervation in rat first molars during tooth maturation. METHODS: We used single and double immunocytochemistry to study molars of rats aged 10 days to 1 year. Neural patterns were compared with odontoblast maturation stages, dentinogenesis, formation of cell-free and cell-rich zones, and root closure. RESULTS: Spatial and temporal patterns showed that most CGRP-IR and PER-IR have different terminal domains in teeth. PER-IR fibers were well established among immature odontoblasts prior to tooth eruption, but CGRP-IR fibers were absent. Two weeks after eruption of first molars, many CGRP-IR beaded fibers entered dentin, the larger PER-IR fibers began shifting away from odontoblasts towards the pulp, and the symmetrical PER-IR pulpal pattern was being established. The CGRP-IR fibers continued to increase their asymmetric dentinal innervation until root growth was completed, during which time odontoblasts matured, the cell-free and cell-rich zones appeared, and roots closed. CONCLUSIONS: Sensory maturation of rat molars coincides with closed root apices, extensive innervation of dentin by CGRP-IR nerve fibers, and the appearance of the mature avascular odontoblast layer next to cell-free and cell-rich zones in the pulp horns.

Animals↗
PubMed2004

Third mandibular molar radiological development as an indicator of chronological age in a European population.

Assessing biological age in the youth nearby legal age has always represented a stimulating issue for the Italian forensic scientist as far as he deals with matter of imputability and legal or illegal immigration of uncertain age subjects. Since any method of evaluation should of course be accurate, not invasive, reproducible and, as possible, easily exploitable, radiological investigation of age dependent features is the most appropriate instrument to the purpose. Dental development is slower and delayed compared with skeletal bone one, occurring according to a known, regular pattern from whose evaluation a biological age can be assessed with a reasonably restricted span for a certain radiological image. This is the assumption which inspired since 1941 (Schour e Massler) so many anthropologists and forensic and clinic odontologist in investigating biological age by the study of radiological dental morphology. Demirjian and Goldstein [New systems for dental maturity based on seven and four teeth, Ann. Hum. Biol. 3 (1976) 411-421] obtained no differences between two groups of subjects whose age was extimated by the evaluation of 14 teeth in one case and 7 teeth in another, the last being greatly simpler. Afterwards, Thorson (1991), Mincer et al. [The A.B.F.O. study of third molar development and its use as estimator of chronological age, J. Forensic Sci. 38 (1993) 379], Solari and Abramovitc [The accuracy and precision of third molar development as an indicator of chronological age in Hispanic, J. Forensic Sci. (3) (2002) 531-535] and then Prieto Carrero [Evaluation of Chronological Age Based on Third Molar Development in the Spanish Population, Atti del XIX Congresso IALM, Milano, 2003], developed a method based on the evaluation of the radiological development of the alone third molar, according to Demirjian's schematic definitions of crown and root formation. Eight stages of development of the third molar are defined from the time of mineralization appearance of the cusp tips up to complete closing of the apexes. In order to achieve grater precision in discriminating stages F and G, Solari added two stages (F1 and G1), determining 10 stages of maturation of root and crown. Prieto tested the accuracy and precision of this method by the evaluation of about 1300 orthopantomographs of juveniles and young Spanish adults of known age, divided for gender. We analyzed a total of 400 orthopantograms of young Spanish dental patients to evaluate the chronology of the right mandibular third molar development and to assess its correlation with the biological age of the tested. Biological age is attributed with a maximum standard deviation of 2.47 from the mean in the eight stages outline. The greatest limit of the method seems to be the operator experience in determining the dental stage of development. We think that age data coming from such evaluation method should be clearly explained to the magistrate in their true statistical significance and limits.

Adolescent↗
PubMed2005

Relationship between the risk of mandibular angle fractures and the status of incompletely erupted mandibular third molars.

BACKGROUND: Several studies have shown the increased risk of mandibular angle fractures associated with incompletely erupted mandibular third molars. But only a few reports analysed in detail the relationship of the status of eruption of this tooth and this type of fracture. OBJECTIVES: The purpose of this study was to clarify the influence of the eruption status of incompletely erupted mandibular third molars on the incidence of mandibular angle fractures. METHODS: Four hundred and thirty-six mandibular halves in 218 patients with mandibular fractures, aged between 15 and 40 years old, were analysed using panoramic radiographs. RESULTS: The incidence of angle fractures in the mandibular halves with incompletely erupted mandibular third molars was 30.8% and this was statistically significantly higher than that in another group (p<0.0001). Deeply located mandibular third molars clearly showed a higher incidence of this fracture when compared with the adjacent second molar (p<0.0001). CONCLUSION: The results of this investigation showed that incompletely erupted mandibular third molars close to the inferior border of the mandible have a high risk of angle fractures.

Adolescent↗
PubMed2004

The impact of intravenous antibiotics on health-related quality of life outcomes and clinical recovery after third molar surgery.

PURPOSE: We sought to compare recovery for clinical and health-related quality of life (HRQOL) outcomes after third molar surgery in patients treated with or without intravenous antibiotics at surgery. PATIENTS AND METHODS: Fifty-six patients at least 18 years of age and with all 4 third molars below the occlusal plane, treated at 3 clinical centers, were given intravenous antibiotics just before third molar surgery. Clinical and HRQOL outcomes of these patients were compared with those of a nonconcurrent control group (n = 60 patients) who did not receive antibiotics. The control group was selected using the same criteria and treated under the same surgical protocol as the antibiotic group. Differences between the groups were assessed with Cochran-Mantel-Haenszel row mean score statistics. RESULTS: The incidence of delayed clinical recovery defined as a postsurgery visit with treatment was higher in the control group compared with the antibiotic group. In the antibiotic group, 4% had 1 postsurgery visit with treatment; no patient had 2 visits. In the control group without antibiotics, 28% had at least 1 postsurgery visit with treatment (P <.0001) and 13% had at least 2 postsurgery visits with treatment. No statistically significant differences in HRQOL outcomes were found between the 2 groups. CONCLUSIONS: Administration of intravenous antibiotics before third molar surgery may improve clinical recovery in healthy adult patients with all 4 third molars below the occlusal plane, a presenting characteristic that has been suggested as a risk factor for delayed recovery. The findings from this exploratory trial indicate that evaluation of the effectiveness of systemic antibiotic administration with third molar surgery in a randomized, multi-intervention, explanatory clinical trial is warranted.

Adult↗