Relation of the mental foramen to teeth on the mandibles belonging to the Byzantium period

Fifty mandibles belonging to the Byzantium period were studied in order to determine to racial differences about of the localization of the mental foramen according to the mandibular teeth. Mandibles of adult males without missing teeth, proximal decay and proximal attrition were used. On the right side, the most common position of the mental foramen was between the first and second lower teeth (50%), whereas on the left side, the most common position was in line with the longitudinal axis of the lower second premolar tooth (46%). Because of materials including mostly Alpine's and a few of Mediterranean subraces, two different positions of the mental foramen were determined in high similar ratios.     

The localization and anthropometry of mental foramen on late Byzantine mandibles

Comprehensive studies of the human skeletal features and variations between and within populations are beneficial both for clinical applications and determination of racial characteristics of populations. The aim of this study was to examine the location and anthropometric characteristics of the mental foramen in 36 adult male mandibles of the Late Byzantine period. The results demonstrated that the most common position of the mental foramen was in line with the longitudinal axis of the second premolar (50% right side; 47% left side) followed by a location between the first and second premolars (33% right side; 36% left side). When compared with the results of previous similar studies, the results obtained in the present study suggest that traits such as the localization of mental foramen may not only differ between populations of different geographic environment but also within the inhabitants of the same geography.     

A clinical and anatomical study of the location of the mental foramen in adult Chinese mandibles

One hundred mandibles of adult Chinese cadavers of both sexes without missing teeth, alveolar bone resorption and malposition of teeth were studied. The anatomical location of each mandibular mental foramen was measured by using a combination of three previous methods. Our results showed that the location of the mental foramen below the apex of the lower second premolar (relation IV: 58.98%) was the most common. On average, the distance between the most anterior portion of the anterior border of the mental foramen and the mandibular symphysis was 28.06 mm, between the most anterior portion of the anterior border of the mental foramen and the posterior border of the ramus 74.14 mm, between the inferior border of the mental foramen and the lower border of the mandibular body 14.70 mm, between the superior border of the mental foramen and the bottom of the lower second premolar socket 2.50 mm. The distance across the mental foramen between the alveolar crest and the lower border of the mandibular body was 30.29 mm. Our results were compared with those of other investigators. The significance of identifying the anatomical location of the mental foramen in dental practice is discussed.     

A comparison of the position of the mental foramen in Chinese and British mandibles

The antero-posterior position of the mental foramen was studied in 68 Chinese and 44 British skulls of known or calculated age at death. All skulls showed low pre-mortem tooth loss and had a good occlusion. The position of the foramen was related to the body of the mandible as well as to the standing mandibular teeth using two previously published methods. There was no significant difference in the size of the Chinese and British mandibles. There was a significant difference between the two groups when measurements relating the foramen to the body of the mandible (symphysis menti) were considered, the foraminal position being more distal in the Chinese group. The modal position of the foramen in the Chinese sample was along the long axis of the second premolar, whereas in the British sample it lay between the apices of the first and second premolar. The foraminal position apparently moved distally in both groups with age and this was likely to be associated with mesial tooth drift and age-related attrition.     

Analysis of the CFTR gene in Turkish cystic fibrosis patients: identification of three novel mutations (3172delAC, P1013L and M1028I)

In order to determine the spectrum of cystic fibrosis (CF) mutations in the Turkish population, a complete coding region of the cystic fibrosis transmembrane conductance regulator (CFTR) gene including exon-intron boundaries, on 122 unrelated CF chromosomes from 73 Turkish CF families was analysed by denaturing gradient gel electrophoresis and multiplex heteroduplex analysis on MDE gel matrix. In addition to 15 previously reported mutations and 12 polymorphisms, three novel mutations, namely 3172delAC, P1013L and M1028I, were detected. ΔF508 was found to be present on 18.8% of CF chromosomes. The second most common mutation was 1677delTA, with a frequency of 7.3%, followed by G542X and 2183AA→G mutations, with frequencies of 4.9%. These four most common mutations in Turkish CF population account for approximately 36% of mutations. This study could only detect 52.5% of disease-causing mutations in this population; 47.5% of CF alleles remain to be identified, reflecting the high molecular heterogeneity of the Turkish population. Received: 16 June 1997 / Accepted: 18 September 1997     

The course of the inferior alveolar nerve in the normal human mandibular ramus and in patients presenting for cosmetic reduction of the mandibular angles

This study was undertaken to quantify the path of the inferior alveolar nerve in the normal human mandible and in the mandibles of patients presenting for cosmetic reduction of the mandibular angles. The goals were: (1) to provide normative information that would assist the surgeon in avoiding injury to the nerve during surgery; (2) to characterize gender differences in the normal population; and (3) to compare the course of the nerve in the normal population to its course in a group of patients who presented with a complaint of "square face." The study was based upon the computerized tomographic scans of 10 normal patients (six men, four women) and 8 patients (all women) complaining of "square face." Using AnalyzePC 2.5 imaging software, the mandibles were segmented and the position of the nerve was recorded within its osseous canal in the mandibular ramus on each axial slice in which it was identifiable. Distances were calculated between the nerve and the anterior, posterior, lateral, and medial cortices. The positions of the lateral ramus prominence and the lowest point on the sigmoid notch were also recorded. The position of the mental foramen was recorded in relation to the nearest tooth, and the three-dimensional surface distances from the foramen to the alveolar bone, the inferior border of the mandible, and the mandibular symphysis were determined. The distances from the entrance of the nerve into the mandible to the lateral ramus prominence and the lowest point on the sigmoid notch were calculated. Summary statistics were obtained, comparing differences in gender. The nerve was identifiable in each ramus over a mean distance of 12.7 mm. On average, the lateral ramus prominence was 0.3 mm higher on the caudad-cephalad axis than the point at which the nerve entered the bone, whereas the location of the lowest point on the sigmoid notch was 16.6 mm above the nerve. The average distances from the nerve to the anterior, posterior, medial, and lateral cortices were 11.6, 12.1, 1.8, and 4.7 mm, respectively. Gender differences were significant for all of these except the medial cortex to nerve distance. On average, the mental foramen exited the body of the mandible immediately below the second premolar and the average surface distances from the foramen to the symphysis, the most cephalad alveolar bone, and the inferior border of the body were 30.9, 14.2, and 19.3 mm, respectively. With regard to the patients presenting for mandibular angle reduction, there were a few statistically significant but small scalar differences from normal controls.     

Comparative Morphology of Premolar Foramen in Lagomorphs (Mammalia: Glires) and Its Functional and Phylogenetic Implications

Lagomorphs (a group that consists of pikas, hares, rabbits and allies) are notable for their conservative morphology retained for most of their over 50 million years evolutionary history. On the other hand, their remarkable morphological uniformity partly stems from a considerable number of homoplasies in cranial and dental structures that hamper phylogenetic analyses. The premolar foramen, an opening in the palate of lagomorphs, has been characterized as an important synapomorphy of one clade, Ochotonidae (pikas). Within Lagomorpha, however, its phylogenetic distribution is much wider, the foramen being present not only in all ochotonids but also in leporids and stem taxa; its morphology and incidence also varies considerably across the order, even intraspecifically. In this study, we provide a broad survey of the taxonomic distribution of the premolar foramen in extant and fossil Lagomorpha and describe in detail the morphological variation of this character within the group. Micro-computed tomography was used to examine the hard palate and infraorbital groove morphology in Poelagus (Leporidae) and Ochotona. Scans revealed the course and contacts of the canal behind the premolar foramen and structural differences between the two crown clades. We propose that the premolar foramen has evolved independently in several lineages of Lagomorpha, and we discuss development and function of this foramen in the lagomorph skull. This study shows the importance of comprehensive studies on phylogenetically informative non-dental characters in Lagomorpha.     

Ontogenetic migration of the mental foramen in Neandertals and modern humans

Since the nineteenth century, researchers have noted that Neandertal and modern human adults differ in mental foramen position, although the ontogenetic changes in the position of this feature have only recently come under the scrutiny of paleoanthropologists. Research on mental foramen position has focused on whether this feature is inferior to a particular tooth. However, tooth position may not be a reliable indicator of mental foramen position because of variability in tooth size within and between taxa and during eruption events. As opposed to observing the mental foramen with respect to the postcanine teeth, we examined linear distances from the mental foramen to other mandibular landmarks. Modern human adults may appear truncated, or paedomorphic, in mental foramen position with respect to Neandertal adults. However, infants of the two taxa differ substantially in anterior mandibular form. The initial differences in the shape of the mental region may be related to the embryological position of the mental foramen in modern humans and its role in the development of the mental trigone. The shape changes that accrue thereafter, possibly from faster mandibular growth rates in Neandertals, further distinguish the adults from one another. Although mandibular shape differences exist from early infancy onwards, adults of the two taxa are broadly similar in bi-mental foramen breadth with respect to mandibular size. For this reason, qualitative assessments of mental foramen position may provide less taxonomic information than previously thought.     

Frequency of premolar teeth extractions for orthodontic treatment

It is of interest to evaluate the frequency of premolar extractions during orthodontic treatment in patients reporting to the Saveetha dental hospital in Chennai from 2019-2020. We used the records from 987 patients who underwent orthodontic treatment from June 2019 to March 2020 in a dental hospital for this analysis. Digital case records of patients who underwent therapeutic extractions of premolars were isolated. A sample dataset of 340 case records were selected for this study. Data shows that 34.4% of subjects underwent premolar extractions amongst a total of 987 subjects who underwent orthodontic treatment. 89.4% of patients were Angle''s Class I malocclusion patients, and the rest were Class II patients. However, no premolar extractions were done in Class III patients. Data also shows that 67.1% of subjects underwent all 4 first premolar extractions and 13.2% underwent only upper first premolar extractions. Thus, a significant association was found between Type of Malocclusion and the Type of premolar extractions with p < 0.05. Moreover, only 34.4% of patients underwent premolar extractions and the majority of them underwent all 4 first premolar extractions.     

Mental foramen and mental nerve: changes with age

In a study of 525 dry mandibles and dissections in 50 cadavers, the mental foramen (MF) was found: single in 94.67% of the cases and multiple in 5.33%. Its shape was round in 34.48% with an average diameter of 1.68 mm and oval in 65.52% with an average long diameter of 2.37 mm. In 43.66% the MF was located in front of the apex of the root of the second premolar. In children before tooth eruption, the MF is somewhat closer to the alveolar margin; during the eruption period, the MF descends to half way between the margins, and in adults with the teeth preserved, the MF is somewhat closer to the inferior border. With loss of teeth and bone resorption the MF moves upwards closer to the alveolar border. In extreme cases of resorption the MF and the adjacent part of the mandibular canal are open at the alveolar margin. In the dissections the findings were similar. The mental nerve emerged from the MF closer to or at the alveolar border, according to the degree of resorption. In extreme degrees of resorption, the mental nerve and the final part of the inferior alveolar nerve were found directly under the gums. In these cases, the vestibular grooves became very shallow, and the mucosa passed directly from the cheeks over the alveolar ridge. Practical implications of the changes of the MF and mental nerve are discussed.     

Familial similarity in dental arch form and tooth position.

This study was done to quantify and compare similarities in dental arch form and tooth position among individuals of various degrees of biological kinship. The sample consisted of 360 dental casts selected from 102 Japanese families, each including both parents and one of their offspring. Most of the subjects had well-aligned permanent dentitions. Coefficients of dissimilarity were obtained by orienting two standard-sized dental arch diagrams plotted from occlusal photographs to the position of best fit. Dissimilarity between adults and children from different families was computed and served as the control data. With few exceptions, the mean dissimilarity between parents and offspring was smaller than that of the nonfamilial pairings; however, statistical differences were not always significant. Among all the teeth observed, the position of both upper and lower central incisors was found to exhibit the least familial similarity. Analysis of variance among pairings of different sources of variation suggested the existence of significant additive genetic effect, both autosomal and sex-linked. Relative contribution of the additive genetic effect in the total variability of this sample was estimated for dental arch form and tooth position to be in the range of 55-60% and 39-77%, respectively. Autosomal additive genetic effects appear to strongly account for the variation in position of the second premolar and of the first molar.     

Geometric morphometric analysis of the crown morphology of the lower first premolar of hominins, with special attention to Pleistocene Homo

This article is the third of a series that explores hominin dental crown morphology by means of geometric morphometrics. After the analysis of the lower second premolar and the upper first molar crown shapes, we apply the same technique to lower first premolar morphology. Our results show a clear distinction between the morphology seen in earlier hominin taxa such as Australopithecus and African early Homo, as well as Asian H. erectus, and more recent groups such as European H. heidelbergensis, H. neanderthalensis, and H. sapiens. The morphology of the earlier hominins includes an asymmetrical outline, a conspicuous talonid, and an occlusal polygon that tends to be large. The morphology of the recent hominins includes a symmetrical outline and a reduced or absent talonid. Within this later group, premolars belonging to H. heidelbergensis and H. neanderthalensis tend to possess a small and mesiolingually-displaced occlusal polygon, whereas H. sapiens specimens usually present expanded and centered occlusal polygons in an almost circular outline. The morphological differences among Paranthropus, Australopithecus, and African early Homo as studied here are small and evolutionarily less significant compared to the differences between the earlier and later homin taxa. In contrast to the lower second premolar and the upper first molar crown, the inclusion of a larger hominin sample of lower first premolars reveals a large allometric component.     

3D Mapping of Safe and Danger Zones in the Maxilla and Mandible for the Placement of Intermaxillary Fixation Screws

Intermaxillary (IMF) screws feature several advantages over other devices used for intermaxillary fixation, but using cone beam computed tomography (CBCT) scans to determine the safe and danger zones to place these devices for all patients can be expensive. This study aimed to determine the optimal interradicular and buccopalatal/buccolingual spaces for IMF screw placement in the maxilla and mandible. The CBCT volumetric data of 193 patients was used to generate transaxial slices between the second molar on the right to the second molar on the left in both arches. The mean interradicular and buccopalatal/buccolingual distances and standard deviation values were obtained at heights of 2, 5, 8 and 11 mm from the alveolar bone crest. An IMF screw with a diameter of 1.0 mm and length of 7 mm can be placed distal to the canines (2 - 11 mm from the alveolar crest) and less than 8 mm between the molars in the maxilla. In the mandible, the safest position is distal to the first premolar (more than 5 mm) and distal to the second premolar (more than 2 mm). There was a significant difference (p<0.05) between the right and left quadrants. The colour coding 3D template showed the safe and danger zones based on the mesiodistal, buccopalatal and buccolingual distances in the maxilla and mandible.The safest sites for IMF screw insertion in the maxilla were between the canines and first premolars and between the first and second molars. In the mandible, the safest sites were between the first and second premolars and between the second premolar and first molar. However, the IMF screw should not exceed 1.0 mm in diameter and 7 mm in length.     

Tooth wear and the position of the mental foramen

Variation in the position of the mental foramen with respect to the teeth ("apparent" position) seems to be associated with race, but in the determination of this position, factors which affect the disposition of the teeth plainly have a bearing on the results. The apparent position was investigated in a sample of southern Chinese skulls of known age which were classified by the degree of tooth wear. Controlling for "true" position and size of the mandible, a highly significant correlation between wear and position was found, age and tooth size having no significant contribution as additional explanatory variables. The effect of tooth wear on the apparent position of the foramen may partly explain racial variation.     

Polymorphism of the fourth component of complement in Turks

An analysis of polymorphism in the fourth component of human complement (C4) was performed on EDTA-plasma from 142 unrelated, randomly selected Turks without collagen-vascular disease or recurrent infections. Plasma samples treated with neuraminidase and carboxypeptidase-B were subjected to high-voltage agarose gel electrophoresis followed by immunofixation. C4B allotypes were further detected in some samples by Western blots with monoclonal antibody 1228 (anti-C4B/Ch1 reactivity). The frequencies of C4A and C4B alleles were determined. Allele C4B*5, which has been found to be relatively common in Asian (Oriental) populations, was not detected in this study. No specific predilection could be noted among the rare variants. C4A*3-C4B*1 was the most common haplotype (n = 40/142, or 28%) but was found less frequently than in Caucasian populations. This finding may be the result of the limited number of samples examined. C4A and/or C4B null allotypes were seen in 49 of 142 (34.6%) subjects. The most frequent C4 null allotype seen was C4B null (37/142, or 26%): 28 subjects had one C4B null allele; 1 had a homozygous deficiency of C4B (C4B*QO, *QO) and 7 had C4A*QO C4B*QO, a double heterozygous haplotype. Frequencies of homozygous haplotype C4A*Q0-C4B*Q0 in the population studied were found to be 0.007. The results of this study demonstrate that the genetic composition of the Turkish population exhibits both similarities and differences with the European population, and ranges between Caucasian and Mongoloid (Asian) populations.     

Frequency of angiotensin II type 1 receptor gene polymorphism in Turkish acute stroke patients

This study was performed in acute stroke patients in the Turkish population to determine the frequency of the A1166C polymorphism in the AT1 gene and to examine the role of this polymorphism in acute stroke development. In this study, 257 genomic DNA samples were analysed (from 206 acute stroke patients and 51 healthy individuals). Genomic DNA was prepared from peripheral blood using the salt‐extraction method. The presence of the A1166C polymorphism in the AT1 gene was determined using the polymerase chain reaction (PCR)‐restriction fragment length polymorphism (RFLP) method. PCR products were separated by 2% agarose gel electrophoresis and visualized by a charge‐coupled device (CCD) camera. In this study, the allele frequency at the A1166C position was 92% A and 8% C for control and 97% A and 3% C for patients. This difference in allele frequency between the control group and the patient group was not statistically significant. However, genotype and allele frequencies showed a significant difference (P < 0.001) in the control and the patient groups. The results of this study show no relationship between the A1166C polymorphism in the AT1 gene and acute stroke in the Turkish population.     

p53 codon 72 polymorphism is associated with susceptibility to hepatocellular carcinoma in the Turkish population: a case–control study

The tumor suppressor p53 gene plays a crucial role in preventing carcinogenesis through its ability to induce cell cycle arrest and apoptosis following DNA damage and oncogene activation. A guanine (G)/cytosine (C) common single nucleotide polymorphism (SNP) at second position of codon 72 in exon 4 of p53 gene determines a arginine (Arg) to proline (Pro) (Arg72Pro) aminoacidic substitution within the proline-rich domain of p53 protein. Arg72 and Pro72 allele are different from a biochemical and biological point of view and many reports suggest that they can modulate individual cancer susceptibility. To determine the association of the p53 Arg72Pro polymorphism with the risk of hepatocellular carcinoma (HCC) development in a Turkish population, a hospital-based case–control study was designed consisting of 119 subjects with HCC and 119 cancer-free control subjects matched for age, gender, smoking and alcohol status. The genotype frequency of the p53 Arg72Pro polymorphism was determined by using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. Our data shows that the Pro/Pro genotype of the p53 Arg72Pro polymorphism is associated with increased risk of HCC development in this Turkish population (OR = 3.20, 95% CI: 1.24–8.22, P = 0.02). Furthermore, according to stratified analysis, a significant association was observed between the homozygote Pro/Pro genotype and HCC risk in the subgroups of male gender (OR = 3.01, 95% CI: 1.14–7.97, P = 0.03) and patients with hepatitis B virus (HBV)-related HCC (OR = 4.04, 95% CI: 1.46–11.15, P = 0.007). Because our results suggest for the first time that the Pro/Pro homozygote of p53 Arg72Pro polymorphism may be a genetic susceptibility factor for HCC (especially in the male gender and HBV-infected patients) in the Turkish population, further independent studies are required to validate our findings in a larger series, as well as in patients of different ethnic origins.     

A new case of Martsolf syndrome

Martsolf syndrome is an autosomal recessive syndrome characterized by microcephaly, mental retardation, cataract, hypogonadism and short stature. A seven-year-old boy was admitted to the hospital with growth retardation and difficulties in walking. His parents were first cousins. Bilateral lens extraction was performed during infancy because of congenital cataract. On physical examination he had short stature, microcephaly, micropthalmia, hypogonadism, mental retardation. Brain magnetic resonance imaging revealed alterations in the white matter. Up to date very few cases with this syndrome have been reported. This is the first case described in the Turkish population and may add valuable information to the literature.     

Polymorphism of dental formula and segregation of its variants in a pedigree of kerry blue terrier dogs

Polymorphism of the dental formula was analyzed in a sophisticated pedigree of Kerry Blue Terrier. A lack of one or more lower premolars was observed in some dogs. Two different patterns of missing teeth were identified. One pattern consisted in agenesis of a second premolar, often in combination with agenesis of neighbor teeth, including the fourth premolar. In the second pattern, agenesis of a fourth premolar was expressed as an isolated abnormality. It was shown previously that the first pattern is inherited as a recessive trait with near complete penetrance. In this work, the control of a major-gene was demonstrated for the second pattern. This abnormality develops in 70-80% of mutant homozygotes and in no more than 20% of heterozygotes and wild-type homozygotes. It was shown that the two dentition abnormalities are controlled by different genes, which were designated LPA2 and LPA4 (Lower Premolar Agenesis).