Mandibular First Molars Research Articles

Local anaesthesia using Articaine and Lidocaine in oral and dental surgery: A comparative meta-analysis

Background: Articaine is an amide local anaesthetic, which is gaining popularity for use in dental and oral surgical anaesthesia in the United Kingdom. Hitherto there has been insufficient evidence to recommend articaine above the more commonly used lidocaine for dental procedures. The aim of this study is to compare the efficacy of 4% articaine with 1:100,000 adrenaline (4AA) with that of 2% lidocaine with 1:100,000 adrenaline (2LA) administered as buccal infiltrations for anaesthesia in mandibular permanent first molar teeth. Any significant advantage noted may obviate the need for regional blockage of the inferior dental nerve in dental or minor oral surgical procedure under local anaesthesia. Objectives: To review the published literature comparing the efficacies of 4AA and 2LA for achieving pulpal anaesthesia in human mandibular permanent first molar teeth. Null Hypothesis: 4AA and 2LA are of equal efficacy when used to anaesthetize mandibular permanent first molar teeth by buccal infiltration. Method: An electronic search encompassing Ovid MEDLINE?, PubMed (National Center for Biotechnology Information, US National Library of Medicine), SCOPUS?, SCIRUS?, EMBASE? databases and the Cochrane Library was performed to identify trials relating to the efficacy of 4AA and 2LA local anaesthetic solutions on mandibular first molars in adult participants. Study characteristics and outcome data were extracted as a basis for meta-analysis. Results: Three randomised controlled trials were identified for this meta-analysis. The relative efficacy of 4AA over 2LA in anesthetizing permanent first mandibular molars was calculated at 1.57 (95% CI = 1.27 to 1.95). Conclusion: Despite the promising results shown in the meta-analysis it is difficult to say from the evidence presented that 4AA should be used clinically in preference over 2LA.

Dental anomalies associated with malocclusion among 13 year old Kurdish students

The aim of this national oral health survey was to determine the prevalence of malocclusions due to some anomalies in the dentition among the 13 years old Kurdish students in sulaimani intermediate school. Materials and methods: The total sample was 950 (455 males and 495 females) which assessed by diagnostic set and special instrument. The clinical examination was mainly based on the definitions of Bjork et al. Some variables were recorded as present or absent sometimes denoting the tooth or the teeth involved in malocclusion and their distribution according to the whole sample. Results: The results showed that 1)The most common extracted tooth was the mandibular first molar (2.9%). 2) At this age group the most common partially erupted tooth was the maxillary canine (4.2%). 3) The most common unerupted tooth was the maxillary second molars. 4) The most common retained deciduous tooth was the maxillary canine (6.8%), then the maxillary second molars (5.4%).5) Hypodontia as judged clinically was found in 2.1% of the sample affecting one or more permanent teeth. The most common congenitally missing tooth was the maxillary lateral incisor (0.9%), mandibular second premolars (0.4%), and then maxillary second premolar (0.2%). 6) 29.2 % of the sample had one or more rotated teeth. The most common rotated tooth was the mandibular second premolars (5.3%). 7). The sample showed 30.4% with one or more displaced teeth. The most common displaced tooth was the maxillary lateral incisor (8.8%), then the maxillary canine (7.2%). Conclusion: At the age of 13 both males and females show large range of dental anomalies that are better to be

Bone Morphogenetic Protein-4 rs17563 T/C Gene Polymorphism with Radix Entomolaris of Mandibular First Molars in the Taiwanese Population

Background: Bone morphogenetic protein-4 (BMP-4) plays an important role during the embryonic development of tooth and bone. Studies have shown around 20% to 35% of Taiwanese exhibit an extra distolingual root, radix entomolaris, in the first mandibular molar. However, the association of the polymorphisms with the mandibular first molar exhibiting a distolingual root has never been evaluated. Methods: Two hundred Taiwanese were grouped using two different characteristics: subjects with and without distolingual roots. BMP-4 polymorphism was evaluated by polymerase chain reaction-restriction fragment length polymorphism, and compared among the groups for each characteristic. Results: Twenty four subjects showed the presence and 92 the absence of the root. The distributions of age, gender, and the habits of smoking, betel nut chewing, and drinking were similar in these two groups. No differences in genotype and allele distributions between the two subject groups were shown. This was regardless of the homo- and hetero-zygosity of C/ T, between TT and CT+CC, and between the alleles of T and C. Comparing the distribution of T or TT in the two subject groups, the odds ratio and the adjusted odds ratio in the genotypes and the allele of C were further confirmed with non-difference. Conclusions: The BMP-4 polymorphism may not be correlated with the presence of distolingual roots.

Endo Periodontal Lesion — A Case Report

The pulp and periodontium have embryonic, anatomic and functional inter-relationships. The simultaneous existence of pulpal problems and infl ammatory periodontal disease can complicate diagnosis and treatment planning. This case report evaluates the effi cacy of decalcifi ed freeze dried bone allograft along with bioabsorbable barrier membrane in the management of furcation defect associated with an endo-perio lesion in a right mandibular fi rst molar. A 36-year-old male patient with an endo-perio lesion in the right mandibular fi rst molar was initially treated with endodontic therapy. Following the endodontic treatment, the furcation defect was treated using decalcifi ed freeze dried bone allograft (DFDBA) along with guided tissue regeneration (GTR) membrane. At the end of 9 months, there was a gain in the clinical attachment level and reduction in probing depth. Radiographic evidence showed that there was a signifi cant bony fi ll.

Evaluating root and canal configuration of mandibular first molars with cone beam computed tomography in a Turkish population

Background/purposeDuring root canal therapy, third roots of mandibular first molars (MFMs) provide an important route for bacterial leakage that can lead to root canal treatment failure and the need for additional surgical intervention. Therefore, the aim of this study was to investigate root and canal morphology of permanent MFMs in a Turkish population using cone beam computed tomography (CBCT). Materials and methodsWe collected 533 CBCT images of MFMs; 81 subjects had unilateral molars and 226 subjects had bilateral molars. The following observations were made: (1) root number; (2) number of canals per root; and (3) root canal configuration in each root using Vertucci's classification with additional modifications. ResultsThe frequency of three-rooted MFMs was 2.4%. Of the 533 MFMs examined, two canals were present in 0.4%, three canals in 69.9%, four canals in 28.7% and five canals in 1.0%. The most common canal morphology in the mesial roots was Vertucci type IV (59.5%), followed by type II (32.8%). The distal roots showed predominantly Vertucci type I (74.7%), followed by types II (12.3%) and IV (9.7%). ConclusionOur results showed a low frequency (2.4%) of three-rooted MFMs in a Turkish population. This close to the average root number among people of European descent. Root and canal configurations of MFMs were consistent with previously reported data. CBCT may be recommended as an effective diagnostic modality for identifying root and canal configuration.

Degenerative Changes in Rat Condylar Cartilage Induced by Non-Matching Occlusion Created by Scattered Orthodontic Teeth-Moving

The effect of occlusion on the temporomandibular joint (TMJ) is debated. By inserting rubber-bands that were replaced by self-curing resin one week later, the left maxillary and the right mandibular first-molars were moved and kept mesially in Sprague-Dawley (SD) rats in both experimental I (EXP-I) and II (EXP-II) groups, aiming to establish a non-matching cusp-to-fossa occlusal relation. Four weeks later, the left maxillary and the right mandibular third-molars were moved and kept distally in the EXP-II group. Degenerative changes, typically as a cell-free area, were observed in TMJs of the EXP groups. Binary logistical analysis indicated that the odds ratio of EXP group, EXP-II vs. EXP-I, on the incidence of a cell-free area, was 2.8 (p=.036). Time point, gender, and side did not have such effects (p>0.05). The results indicate that the persistence of more scattered non-matching cusp-to-fossa occlusion is more harmful to the condylar cartilage in terms of the incidence of degenerative changes.

Clinical investigation of radix entomolaris in mandibular first molars

To investigate the prevalence and treatment of radix entomolaris (RE) in mandibular first molars. 378 cases of mandibular first molars with root canal therapy were collected. The case included clinical records and periapical radiographs of preoperative, intraoperative and postoperative. The root number, root canal number and root canal therapy were investigated. The RE prevalence of mandibular first molars was 26.98% (102/378). Both gender and bilateral occurrence of RE did not show a significantly difference (P>0.05), but there was a significantly greater incidence of instrument separation, lateral perforation and underfill of the root canals in RE than other canals in mandibular first molars (P<0.05). The RE prevalence of mandibular first molar is high and there is a significantly greater incidence of instrument separation, lateral perforation and underfill of the canals in RE than other canals in mandibular first molars.

Effect of thermal and mechanical loading on marginal adaptation and microtensile bond strength of a self-etching adhesive with caries-affected dentin

Aim:This study evaluated the effect of thermal and mechanical loading on marginal adaptation and microtensile bond strength in total-etch versus self-etch adhesive systems in caries-affected dentin.Materials and Methods:Forty class II cavities were prepared on extracted proximally carious human mandibular first molars and were divided into two groups: Group I — self-etch adhesive system restorations and Group II — total-etch adhesive system restorations. Group I and II were further divided into sub-groups A (Without thermal and mechanical loading) and B (With thermal and mechanical loading of 5000 cycles, 5 ± 2°C to 55 ± 2°C, dwell time 30 seconds, and 150,000 cycles at 60N). The gingival margin of the proximal box was evaluated at 200X magnification for marginal adaptation in a low vacuum scanning electron microscope. The restorations were sectioned, perpendicular to the bonded surface, into 0.8 mm thick slabs. All the specimens were subjected to microtensile bond strength testing. The marginal adaptation was analyzed using descriptive studies, and the bond strength data was analyzed using the one-way analysis of variance (ANOVA) test.Results and Conclusions:The total-etch system performed better under thermomechanical loading.

DIAGNOSIS AND TREATMENT OF MANDIBULAR FIRST MOLAR WITH THREE MESIAL ROOT CANALS -A CASE REPORT

The knowledge of the internal anatomy of root canals is very important for the success of endodontic treatment. Variations in dental anatomy are found in all teeth. Lack of knowledge of anatomic variations and their characteristics in different teeth has been one of the main causes of endodontic therapy failure. This case report describes the endodontic treatment of a mandibular first molar with five root canals, its incidence of occurrence and discusses the importance of their identification and treatment.

Establishment of the three dimensional finite element model of the first permanent mandibular molar

Objective To construct a rational and exact three - dimensional finite element model of the first permanent mandibular molar. Methods The first permanent mandibular molar was scanned by CT and the images were processed by softwares such as PhotoShop. Then special software SolidWorks2010 was used to establish a three - dimensional finite element model . Results A three - dinensional finite element model of the first permanent mandibular molar was established, including enamel, dentin, pulp, alveolar bone and periodontium. Conclusion The modeling method is effective and reliable. The three- dimensional finite element model has favorite similarities in geometry and biomechanics . It' s a simple and precise method for dentists to establish finite element models . Key words: Molar; Three- dimensional finite element; Model

Investigation of fourhanded technique assorted nursing in root canal therapy

Objective To investigate the fourhanded technique assorted nursing in root canal therapy. Methods To select 80 patients of root canal therapy on the first mandibular molar with non-system affection in department of stomatology,the treatment group treated by fourhanded technique assorted nursing were 40 cases, control group treated by usual care were 40 cases, observing time and quality of therapy.Results the treatment group was better than control group in curative effect (P＜0.05).Conclusions there was satisfactory effect in fourhanded technique assorted nursing in root canal therapy. Key words: Fourhanded technique; Root canal therapy

Removal of a Separated Nickel-titanium Instrument from a Three-rooted Mandibular First Molar

Permanent mandibular first molars usually have a mesial root and a distal root and three root canals, but variations in the number of roots and in canal morphology are not uncommon. The additional third root in permanent mandibular first molar variants that have three roots is typically distributed lingually. Herein, we report on a 20-year-old Chinese female who presented with a separated K3 nickel-titanium instrument in the distolingual root canal of her left mandibular first molar. We removed the nickel-titanium fragment using several ultrasonic tips under a dental operating microscope. The root canals were cleaned and shaped thoroughly and then obturated by a warmed gutta-percha compaction method. At 4-month follow-up, the patient was free of symptoms.

Changes in mandibular third molar angle and position after unilateral mandibular first molar extraction

Third molars often become impacted because of lack of space for their eruption. Because the third molars play an important role occlusally, premolars or second molars are sometimes extracted to create space. First molars are seldom extracted to create space, but they are occasionally extracted for other reasons, especially caries. The aim of this study was to investigate the spontaneous angular and positional changes in mandibular third molars when mandibular first molars are extracted. The sample consisted of panoramic radiographs of 107 patients (age, 18-40 years; mean, 25.69 years) who had unilateral mandibular first-molar extractions (because of caries) before age 16. Ramus relationship, impaction depth, and angulation of third molars on the extraction and nonextraction sides were assessed. A chi-square test was performed to compare the differences. The prevalence of third molars at the anterior border of the mandibular ramus was significantly greater on the extraction side than on the nonextraction side (P < .001). Third molars were positioned more occlusally in the mandible on the nonextraction side than on the extraction side (P < .001). The prevalence of vertically angulated third molars was greater on the extraction side than on the nonextraction side (P < .001). Mandibular first-molar extraction increases the space for mandibular third-molar eruption and helps the third molars move into better positions. But early extraction can lead to uncontrolled tipping of adjacent teeth into the extraction space. Only third-molar angle and position were evaluated in this study; problems such as dental asymmetry, premature contacts, and uncontrolled tipping should be assessed in the future.

Establishment of the three-dimensional finite element model of the first permanent mandibular molar and its stress analysis

To establish more rational three dimensional finite element model (FEM) of the first permanent mandibular molar and to study the internal stress distribution. The FEM was applied to analyze the stress distribution of the first permanent mandibular molar under various loading conditions. Under all five loading conditions, the maximum von-Mises stress and compressive stress in enamel were larger than that in dentin, and the tensile stress in enamel was smaller than that in dentin. When vertical force and buccal-lingual oblique force were loaded, the stresses in the enamel and dentin were minimum; when lingual-buccal oblique force was loaded, the stresses were maximum; the stresses were mainly distributed at cervical region, furcation and apical area of the mesial-lingual root canal wall. The stress value changes and stress distribution in the enamel and dentin were closely related with the direction of the occlusion force.

Enamelin transcriptional expression in developing postnatal rat tooth germ

To observe the transcriptional expression of enamelin in developing postnatal rat first mandibular molar germs, for further studies of functions of enamelin in enamel development and mineralization. Tissue slices of first mandibular molar germ of rat 1, 3, 7, 10, 14 days after birth were prepared. The enamelin mRNA expression was identified by in situ hybridization. Enamelin mRNA was observed in both ameloblast and odontoblast in 1-10 day old rat postnatal first mandibular molar germs. Enamelin mRNA appeared very weakly at 1st day, and increased through 3rd day, reached the maximum at 7th day, and reduced at 10th day and became negative at 14th day postnatally; while the expression of enamelin mRNA in odontoblast maintained lower from 1st to 10th day and negative at 14th day postnatally. Enamelin gene transcriptional expression lasts from preameloblast to maturation ameloblast, which suggests that enamelin may participate in the development of enamel and mantle dentin.

Influence of orthodontic forces on the distribution of proteoglycans in rat hypofunctional periodontal ligament.

During orthodontic treatment, it is often necessary to move the hypofunctional teeth. In this study, we revealed an influence of orthodontic forces in the hypofunctional periodontal ligament, and focused on the distribution of proteoglycans, major extracellular matrix molecules. Five-week-old rats were divided into normal group and hypofunctional group. To induce occlusal hypofunction, occluding teeth of the mandibular first molar were extracted. At 8-week-old, orthodontic force by 15 or 2 gf titanium-nickel alloy closed coil spring was applied to the mandibular first molar toward the mesial direction. Immunohistochemical analysis was performed using antibodies for chondroitin sulfate (CS) and heparan sulfate (HS). In normal group, CS was observed throughout the extracellular matrix, while HS was observed on the endothelial cells and the osteoclastic cells on compressive side. In hypofunctional group without orthodontic appliance, CS and HS were detected in less amounts. With 15 gf, CS was observed at the compressive area where no cells and fibers were present, and HS was observed at the periphery of this area. With 2 gf, however, the distribution of CS and HS was similar to the normal control. These findings indicate that CS and HS were affected by orthodontic forces, and suggest their distinct functions in tissue remodeling.

Analysis of divergent angle and length of CEJ to furcation entrance in extracted molars

The purposes of this study were to investigate the furcation entrance angle (FEA) and the distance between cemento-enamel junction (CEJ) and furcation entrance (FE) of the extracted maxillary and mandibular molars. Assay teeth comprised 89 maxillary molars and 93 mandibular molars. All the FEAs and CEJ-FEs of the molars were measured by a stereomicroscope at 2.5 x equipped with a Bioscan OPTIMAS Image Analyzer (BOIA). The results were summarized as follows: (1) The mean FEAs in the buccal, mesial and distal furcations were 96.3 +/- 10.0, 103.8 +/- 9.7, and 107.2 +/- 12.2 degrees in the maxillary molars, and 91.6 +/- 11.7, 101.7 +/- 11.5, and 97.1 +/- 10.7 degrees in the maxillary second molars, respectively. At the buccal and lingual furcations of mandibular first and second molars, they measured 100.5 +/- 9.7/102.7 +/- 8.5, and 93.3 +/- 11.5/91.7 +/- 10.8 degrees, respectively. (2) The mean distance of CEJ-FEs at the buccal, mesial and distal furcations of maxillary molars were 3.42 +/- 1.5mm, 3.55 +/- 0.97 mm, and 3.69 +/- 0.98mm for the first molars, and 3.01 +/- 1.04mm, 4.04 +/- 1.58mm and 3.00 +/- 1.14mm for the second molars. At the buccal and lingual furcations of the mandibular first and second molars, they were recorded as 1.90 +/- 0.08mm and 2.90 +/- 0.07mm, and 2.82 +/- 1.34mm and 3.46 +/- 1.03mm, respectively. It was concluded that buccal FEA of maxillary 2nd molar was the smallest (91.56 +/- 9.68 degrees) as compared to the mesial and distal FEAs; whereas the mean distance of CEJ-FEs at the buccal surface was the smallest (1.90mm +/- 0.08mm) when compared to the others.

Lower molar and incisor displacement associated with mandibular remodeling.

The purpose of this study was to quantify the amount of alveolar modeling at the apices of the mandibular incisor and first molar specifically associated with appositional and resorptive changes on the lower border of the mandible during growth and treatment. Cephalometric data from superimpositions on anterior cranial base, mandibular implants of the Björk type, and anatomical "best fit" of mandibular border structures were integrated using a recently developed strategy, which is described. Data were available at annual intervals between 8.5 and 15.5 years for a previously described sample of approximately 30 children with implants. The average magnitudes of the changes at the root apices of the mandibular first molar and central incisor associated with modeling/remodeling of the mandibular border and symphysis were unexpectedly small. At the molar apex, mean values approximated zero in both anteroposterior and vertical directions. At the incisor apex, mean values approximated zero in the anteroposterior direction and averaged less than 0.15 mm/year in the vertical direction. Standard deviations were roughly equal for the molar and the incisor in both the anteroposterior and vertical directions. Dental displacement associated with surface modeling plays a smaller role in final tooth position in the mandible than in the maxilla. It may also be reasonably inferred that anatomical best-fit superimpositions made in the absence of implants give a more complete picture of hard tissue turnover in the mandible than they do in the maxilla.

Furcation entrance dimension, divergent angle and length of CEJ to furcation entrance relate to periodontal therapy

In previous studies we have investigated the furcation entrance dimension (FED), furcation entrance angle (FEA) and the distance between cementoenamel junction and furcation entrance (CEJ-FE) of the first and second molars and compared the Chinese with the Caucasians. The aim of the present study was to relate the FED, FEA, and distance of CEJ-FE to the clinical significance of periodontal therapy of molar furcations. All the FEDs, FEAs, and distance of CEJ-FEs of the molars were measured by a stereomicroscope equipped with a Bioscan OPTIMAS Image Analyzer and statistically analyzed by Student's paired t-test, multiple regression of ANOVA and correlation analysis. The results are summarized below. (1) There is a significant relationship between FEA and location of buccal, mesial, and distal furcations of maxillary first and second molars (16& 26, p < 0.001; 17&27, p < 0.01). (2) There exists a significant relationship between FEA and FED in the mandibular first and second molars. (3) There exists a significant relationship between FED and FEA in the mandibular second molar (r = 0.370, p < 0.05). (4) The prevalence of mean FED and FEA (type D, FED < or = 0.75 mm and FEA < or = 90 degree) of the maxillary first molar (45%) is twice as high as the maxillary first molar (24%). (5) The prevalence of type D of the buccal (32%) and lingual (37%) furcations on the mandibular second molar is markedly higher than the first molar (buccal = 12%; lingual = 4%, respectively). These results reveal that those topographics of the FED, FEA, and distance of CEJ-FE in second molars have poor prognosis in periodontal therapy when compared with first molars.

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.