Roots Of Mandibular First Molars Research Articles

Mandibular first molar with three distal canals

With the increasing number of reports of aberrant root canal morphology, the clinician needs to be aware of the variable anatomy. Various case reports have been published with the finding of middle mesial canal in mandibular first molar, however finding of middle distal canal in distal root of mandibular first molar is rare. This case report describes root canal treatment of two rooted mandibular first molar with five root canals (three in distal and two in mesial root), and Sert and Bayirli Type XVIII canal configuration in distal root.

Canal and isthmus debridement efficacies of two irrigant agitation techniques in a closed system

To compare canal and isthmus debris debridement efficacies of the manual dynamic irrigation (MDI) and apical negative pressure (ANP) techniques in the mesial root of mandibular first molars with narrow isthmi, using a closed canal design. Micro-computed tomography was employed to select 20 teeth, each containing a narrow isthmus. Each root was sealed at the apex with hot glue and embedded in polyvinylsiloxane to simulate a closed canal system. The teeth were submitted to a standardized instrumentation protocol. Final irrigation was performed with either the MDI or the ANP technique using the EndoVac system (N=10). Masson trichrome-stained sections were prepared from completely demineralized roots at 10 canal levels between 1 and 2.8mm of the anatomical apices. Areas occupied by canals and isthmus of each root and debris in the corresponding regions were digitized by the NIH Image J software and statistically analysed using two-way repeated measures anova. For the instrumented canals, there were no differences between the two groups (P=0.131) in the area occupied by debris at all canal levels (P=0.343). Conversely, for the isthmus, less debris was found in the ANP group (P<0.001) but no differences were seen in each group with respect to the 10 canal levels (P=0.352). Neither technique completely removed debris from the isthmus regions. However, the EndoVac system, which encompasses the ANP concept, removed considerably more debris from narrow isthmi in mandibular mesial roots.

Mandibular First Molar Having an Unusual Mesial Root Canal Morphology with Contradictory Cone-Beam Computed Tomography Findings: A Case Report

Introduction The objective of this article is to highlight the importance of having a thorough knowledge about the root canal anatomy and the possibility of misleading findings in the cone-beam computed tomography (CBCT) images. Methods This case report presents the endodontic management of a right mandibular first molar with 2 roots and 2 canals. A CBCT imaging was performed to ascertain this rare root canal anatomy. Results The clinical and radiographic diagnosis of the existence of a single root canal within the mesial root of mandibular first molar did not correlate with the CBCT findings. Conclusions The confirmative diagnosis should be based on cognitive deduction of the clinical picture and intelligent interpretation of radiologic information.

Middle distal canal of the mandibular first molar: a case report and literature review

To present a clinical case report in a mandibular first molar with a middle distal canal, along with a review of the literature. With the use of magnification, either by microscopes or by loupes, there is an increasing possibility of detecting additional canals. The present case describes root canal treatment in a mandibular first molar with two roots and a Sert and Bayirli Type XVIII canal configuration in the distal root. The presence of a three canals in the distal root of mandibular first molars has been reported to have an incidence of 0.2-3%. * Clinicians should be aware of the variable root canal anatomy in the distal root of mandibular first molars. * Use of magnification helps to identify and locate additional root canals. * Three root canals in the distal root of mandibular first molar teeth might occur.

Thickness of dentine in mesial roots of mandibular molars with different lengths

To measure the minimum thickness of the distal (furcal) root dentine associated with the buccal and lingual canals of the mesial roots of mandibular first molars with different lengths. The mesial roots of 285 mandibular first molars were allocated into three groups according to their length: group I - long (24.14 mm +/- 0.85), group II - medium (22.10 mm +/- 0.65) and group III - short (19.97 mm +/- 0.75). The minimum thickness of the distal (furcal) root dentine associated with the buccal and lingual canals of the mesial roots 2 mm below the furcation was measured. The distance between the buccal and lingual canals, and the depth of concavity in the distal surface of the mesial roots were also measured. anova and Tukey-Kramer were used to test for significant differences among the groups. The minimum thickness of the distal wall of the mesiobuccal canal was significantly different (P < 0.05) between group I (long) and III (short), with long teeth having the smallest mean values. No significant difference was found in the thickness of the distal wall of the mesiolingual canal among the groups studied (P > 0.05). The shortest distance between the mesiobuccal and the mesiolingual canals was observed in group III (P < 0.05). The distal (furcal) concavity was deeper in group I (P < 0.05) when compared with the other groups. There was a significant difference in the minimum thickness of the distal (furcal) root wall of the mesiobuccal canal of mandibular first molars 2 mm below the furcation between group I (long) and group III (short) teeth. The thinnest walls were found in the longest teeth. The deepest concavities in the distal (furcal) walls of the mesial roots were found in the longest roots.

Evaluation of Root and Canal Systems of Mandibular First Molars in Taiwanese Individuals Using Cone-beam Computed Tomography

Cone-beam computed tomography (CBCT) can provide valuable data for root canal systems of human teeth. This study used CBCT to evaluate the number of roots and canals in mandibular first molars in Taiwanese individuals. We screened 151 patients (76 male and 75 female) scheduled for CBCT scan prior to implantation, or orthodontic, endodontic, or periodontic treatment between June 2006 and March 2009 at the Department of Dentistry, Cardinal Tien Hospital, Taipei, Taiwan. A total of 237 image samples of mandibular first molars were obtained and analyzed for their number of roots and canals. We found that 177 (74.7%) mandibular first molars had two roots and 60 (25.3%) had three roots. Of the 237 teeth, 133 (56.1%) had three canals, 96 (40.5%) had four, and eight (3.4%) had two canals. Of the 86 patients (43 male and 43 female) with bilateral mandibular first molars, 22 (25.6%, 15 male and 7 female) had bilateral three-rooted mandibular first molars, and six (7.0%, 4 male and 2 female) had unilateral three-rooted mandibular first molars. The chi(2) test showed a significantly higher incidence of three-rooted mandibular first molars in male (44.2%, 19/43) than in female (20.9%, 9/43, p = 0.038) subjects. Our results showed a high overall incidence (32.6%) of three-rooted mandibular first molars in Taiwanese individuals. CBCT could be a valuable tool for identifying an extra distolingual root in mandibular first molars.

Isthmuses of the mesial root of mandibular first molar - An spiral computed tomographic study

Aim: To investigate invitro the incidence and position of root canal isthmuses in the apical 5 mm of the mesial root of mandibular first molars by means of high resolution spiral computed tomography (SCT) and to describe the morphology of the isthmuses. Methodology: Forty extracted mandibular first molars that had fully formed roots were selected. The mesial roots were sectioned from the distal roots and subjected to SCT. The number of sections showing isthmuses in each of the apical 5 mm of the root canals was recorded. In each one of the apical 5 mm of the 40 roots, a total of 400 sections observed. Data were analysed for the presence of isthmuses at all the sections in each of the apical 5 mm of each root and the morphology of isthmus was also evaluated. Results: Isthmuses were found to be present at all levels with prevalence figures between 18.25 and 50.25%. A significant difference in the distribution of isthmuses within section and it was found that sections in the third millimetre from the apex had more isthmuses Calcifications were found to be present in most isthmuses, occasionally lateral canals originated from the central part of the isthmuses. Conclusion: the incidence of root canal isthmus in the mesial root of the mandibular first molars was high. Particularly in the apical 3-5 mm from the apex. Cleaning the isthmus is a major challenge during root canal treatment. The results of clinical and surgical endodontic procedures performed in the mesial root of mandibular molars may be affected by this aspect of the root canal anatomy.

Nonsurgical approach for strip perforation repair using mineral trioxide aggregate

“Stripping” is lateral perforation is caused by overinstrumentation through a thin wall in the root and is most likely to occur at the inside wall of a curved canal, such as the distal wall of the mesial roots in mandibular first molars. In the past, poor prognosis for strip and furcation perforations was probably due to bacterial leakage or lack of biocompatibility of repair materials. However, the recent development in the techniques and materials such as mineral trioxide aggregate (MTA) has enhanced the prognosis for such cases. There is limited literature on use of MTA as an obturating material in the treatment of strip perforation. This study presents two cases of strip perforation that are successfully repaired nonsurgically using MTA with 2-year follow up. Cases suggest that MTA can be used as an alternative root canal obturation material for the treatment of strip perforation. The property differences between gray and white MTA are reviewed.

The Morphologic Characteristics of the Distolingual Roots of Mandibular First Molars in a Taiwanese Population

Introduction The prevalence of extra distolingual (DL) roots in mandibular first molars in Chinese population is about 20%. The purpose of this study was to evaluate the difference of root length and root curvatures between distobuccal (DB) and DL roots of three-rooted mandibular first molars in a Taiwanese (Chinese) population. Methods Of the 293 extracted mandibular first molars, DL roots were present in 29 (9.9%) teeth. Excluding teeth with fractured DB or DL roots, 21 mandibular first molars were further investigated. DB and DL root lengths were measured from the lower level of furcation at the distal surface to the root apex. The curvature of the DL root was measured on mesial-distal and buccal-lingual radiographs by Schneider's technique. Results The DL roots were significantly (p < 0.001) shorter than the DB roots with an average of 1.48 ± 0.81 mm. Most DL roots had a greater curvature in a buccal-lingual orientation (36.35° ± 9.38°) than a mesial-distal orientation (9.24° ± 6.10°) and 28.57% of the curved DL roots had the curvature at the apical one third (p < 0.001). Conclusion The results of this study verified the characteristics of shorter root length and severe buccal-lingual inclination of DL roots in three-rooted mandibular first molars.

A Microcomputed Tomographic Study of Canal Isthmuses in the Mesial Root of Mandibular First Molars in a Chinese Population

Untreated isthmuses can be a cause of endodontic treatment failure. We investigated the anatomic features of the isthmus in the mesial root of mandibular first molars using microcomputed tomography scans. Thirty-six extracted mandibular first molars were collected from the Chinese population and divided into three age groups as follows: 20 to 39 years (group A), 40 to 59 years (group B),and ≥60 years (group C). Each tooth was scanned and reconstructed, and then the prevalence and type of isthmus were recorded. The percentage of sections showing isthmuses for groups A, B, and C were 50%, 41%, and 24%, respectively. The chi-square test indicated a significant correlation of the distribution of isthmuses with age (p < 0.001). The ratio of partial isthmus to complete isthmus for group C (17.1:1) was significantly higher than group A (5.9:1) and group B (7.0:1) (p < 0.001). By understanding the configuration and location of isthmus, a more efficient endodontic microsurgery can be guaranteed.

Root and canal morphology of the mesiobuccal and distal roots of permanent first molars in a Kuwait population – a clinical study

To identify the number of roots and canal configurations in permanent first molars of the indigenous Kuwaiti sub-population and compare them against a similar group of non-Kuwaiti population in different age groups and gender, and to determine the frequency of a second canal in the mesiobuccal root of maxillary first molars and distal root of mandibular first molars that could be located and treated in routine practice without using magnification or special lighting conditions. A total of 220 permanent first molar teeth of patients scheduled for root canal treatment over a period of 1 year were included. Patients were identified and grouped according to their nationality as Kuwaiti and non-Kuwaiti (which included Filipinos, Indonesian Indians, Srilankans, Egyptians, Saudi Arabians and Syrians). In both nationality groups, patients were successively distributed into four groups based on their age. The first age group included patients below 20 years, the second 21-30 years, the third 31-40 years and the fourth were over 40 years. The first three groups comprised of 15 male and 15 female patients whilst the fourth group had 10 patients of each gender. Teeth with open apices, resorptions and calcification were excluded from the study. The teeth included were both clinically and radiographically examined for number of roots, the canal configuration and the presence of the additional mesiobuccal and distal canals and recorded. The simplified classification of canal configurations proposed by Weine was utilized. The incidence of a second canal in the mesiobuccal (MB) root of maxillary first molars and the distal root of mandibular first molars was not influenced significantly by nationality and gender. All the 110 maxillary first molars treated had three roots; 58% of MB root had one canal and 42% had two canals. The majority of the mesial roots had Weine type II canal configuration when the second mesiobuccal canal was present. All distobuccal and palatal roots had a single or type I canal configuration. Of the 110 mandibular first molars that were treated, 96% had two roots and 4% had three roots. When present, the third root was located either buccal or lingual to the main distal root. Overall 51% of the single distal roots had one canal whilst 49% had two canals. The mesial root frequently had a Weine type II canal configuration as did the distal root when a second canal was present. Pearson's correlation analysis of both molars revealed a significant (P < 0.05) negative correlation (r = -0.274, r = -0.144) between age and number of canals as well as the type of canal. The incidence of a second canal in distal roots of permanent mandibular first molars was 49% in the Kuwaiti population and this was similar to other Asian ethnic populations. Adopting modified access and troughing procedures revealed a 42% frequency of MB2 canals in maxillary first molars. The incidence of a second canal in both mesiobuccal roots of maxillary molars and distal roots of mandibular molars decreased significantly with age; no differences were noticed amongst the nationalities and gender studied. The possibility of extra roots should be anticipated in mandibular molars.

An In Vitro Study of the Number of Distal Roots and Canals in mandibular First Molars in Iranian Population.

The purpose of this study was to evaluate the number of distal roots and canals in mandibular first molars and their internal anatomy radiographically within Iranian population. A total of 310 distal roots of mandibular first molars were incorporated in this study and evaluated in terms of number of roots and number and types of canals. Root canal systems were studied in vitro by means of radiography and based on Vertucci's classifications. It was shown that 4.5% of the teeth in this study had two distal roots, of which, 100% indicated type I for both distobuccal and distolingual roots. Among all the teeth, 43.2% had two canals, 24.2% two apical foramina, and 38.7% two orifices in their distal roots. According to Vertucci's classification 54.9% of the teeth were type I, 19% type II, 1.9% type III, 14.2% type IV, 4.2% type V, 1% type VI, 0.3% type VII and 0% type VIII. In as many as 43.2% of all teeth assessed in this study, bicanaled distal roots were observed, dentists are always recommended to search for the second canal in distal roots of mandibular first molars. In case the second canal in the distal root is missed, failure of endodontic treatment will be anticipated. A rectangular type access cavity design allows better visualization and negotiation of the probable second canals within the distal roots of mandibular first molars.

Root and canal morphology of human permanent teeth in a Sri Lankan and Japanese population

The main purpose of this study was to investigate the root and canal morphology of Sri Lankan and Japanese permanent dentition. Two thousand Sri Lankan and 976 Japanese permanent teeth were examined. The number of roots in premolars and molars and the prevalence of C-shaped (gutter shaped) roots in mandibular second molars were recorded. Root canal morphology was studied using a clearing technique. The examination of root canal systems of the teeth was based on Vertucci’s classification. A higher prevalence of two-rooted maxillary first premolars was observed in Sri Lankans than in Japanese. Sri Lankan maxillary first and second premolars displayed a higher incidence of two canal and two apical foramina forms than those of Japanese. Canal morphology of mandibular first premolars showed higher occurrence of two canals with type V (1-2) canal configuration in Sri Lankans than in Japanese. In mandibular molars, Japanese presented with a higher incidence of three-rooted first molars and one-rooted second molars than Sri Lankans. C-shaped root was seen in 5.7% of Sri Lankan and 18.8% of Japanese second molars examined. In the distal root of mandibular first molars, Japanese showed a higher prevalence of two apical foramina with type IV (2) and additional canal forms than that of Sri Lankans. Japanese mandibular second molars exhibited a higher occurrence of one-root canal forms than that of Sri Lankans. In addition, mandibular incisors and canines of Sri Lankans showed a higher prevalence of two canals with type III (1-2-1) canal form than Japanese. Root and canal morphologies of Japanese and Sri Lankan people are consistent with those of people of East Asian and European (western Eurasia) origin, respectively. In human dentition, the differences of the internal canal morphology are more evident and constant than that of external root morphology among different population groups.

Prevalence of Three-rooted Mandibular First Molars among Taiwanese Individuals

The purpose of this study was to evaluate the prevalence of mandibular first molars featuring a distolingual root among a Taiwanese population. A total of 731 patients' periapical radiographs were screened and examined to obtain 166 samples for this study. The gender, symmetry, and frequencies of occurrence of three-rooted mandibular first molars were recorded. The prevalence of three-rooted mandibular first molars was 21.09%. The bilateral incidence of a symmetrical distribution was 68.57%. There was a significantly greater incidence of three-rooted teeth on the right side of the mandible than on the left, but gender did not show a significant relationship with this variant prevalence. Clinicians should be aware of the high racial prevalence of the distolingual root in mandibular first molars among the Taiwanese (Chinese) population before initiating endodontic treatment.

Microbial status of apical root canal system of human mandibular first molars with primary apical periodontitis after “one-visit” endodontic treatment

To assess the in vivo intracanal microbial status of apical root canal system of mesial roots of human mandibular first molars with primary apical periodontitis immediately after one-visit endodontic treatment. The residual intracanal infection was confirmed by correlative light and transmission electron microscopy. Sixteen diseased mesial roots of mandibular first molars were treated endodontically, each in one visit. Mesio-buccal canals were instrumented using stainless steel hand files and mesio-lingual canals with a nickel-titanium rotary system. The canals were irrigated with 5.25% sodium hypochlorite (NaOCl) during the instrumentation procedures, rinsed with 10 mL of 17% ethylenediamine tetraacetic acid (EDTA), and obturated with gutta-percha and zinc oxide eugenol cement. Thereafter, the apical portion of the root of each tooth was removed by flap-surgery. The specimens were fixed, decalcified, subdivided in horizontal plane, embedded in plastic, processed, and evaluated by correlative light and transmission electron microscopy. Fourteen of the 16 endodontically treated teeth revealed residual intracanal infection after instrumentation, antimicrobial irrigation, and obturation. The microbes were located in inaccessible recesses and diverticula of instrumented main canals, the intercanal isthmus, and accessory canals, mostly as biofilms. The results show (1) the anatomical complexity of the root canal system of mandibular first molar roots and (2) the organization of the flora as biofilms in inaccessible areas of the canal system that cannot be removed by contemporary instruments and irrigation alone in one-visit treatment. These findings demonstrate the importance of stringent application of all nonantibiotic chemo-mechanical measures to treat teeth with infected and necrotic root canals so as to disrupt the biofilms and reduce the intraradicular microbial load to the lowest possible level so as to expect a highly favorable long-term prognosis of the root canal treatment.

Dental root resorption and repair: histology and histometry during physiological drift of rat molars.

The process of dental root resorption and subsequent cementum regeneration has not been sufficiently elucidated. This study aimed to examine the process of the root resorption and cementum regeneration during physiological tooth drift using a rat model, and to evaluate this experimental model. Distal roots in mandibular first molars and the surrounding periodontal tissues were investigated with light and electron microscopy. The light microscopic approach included histochemical and histometric analyses utilizing the tartrate-resistant acid phosphatase (TRAP) reaction. Root resorption was observed in the distal side of the roots and was most active in 5- to 6-week-old rats, and gradually decreased hereafter. An increase in the number of TRAP-positive mononuclear cells, which seemed to be odontoclast precursor cells, preceded the increase in the number of odontoclasts. Root resorption was transient, and was followed by the new formation of acellular extrinsic fiber cementum accompanied with only a slight inflammation, and therefore classified as external surface resorption. Preparation for new cementum started adjacent to the resorption areas when root resorption was most active. The root resorption during drift in rats is transient and followed by acellular extrinsic fiber cementum regeneration. Cellular kinetics suggested that odontoclast precursor cells are supplied as mononuclear cells from vascular spaces.

A preliminary in vitro study of the incidence and position of the root canal isthmus in maxillary and mandibular first molars.

To investigate in vitro the incidence and position of the root canal isthmus in extracted mesiobuccal roots of maxillary and mesial roots of mandibular first molars. Fifty maxillary and 50 mandibular molars were included in the study. The mesiobuccal roots of maxillary molars and the mesial roots of mandibular molars were sectioned from their crowns in the furcation region and embedded in clear resin. Transverse serial 1-mm-thick sections from the apical 6 mm were prepared. The apical side of each section was stained with India ink and observed through a light microscope. The sample images were saved to disk using a digital camera and the root canals in terms of the number present and the incidence and classification of isthmuses. In the mesiobuccal root of the maxillary first molars, 70% had one canal, whereas 29.5% had two canals. In the mesial root of mandibular molars, 41% had one canal, whereas 59% had two canals. In some sections, more than two canals were found close to the apical foramen. The isthmus incidence was greatest 3-5 mm from the apex. In teeth having two canals, a complete or partial isthmus was frequently observed in the sections between 3 and 4 mm from the apex. Of the isthmuses present, 22% were complete and 37% partial in mandibular molars and 17.3% were complete and 11.7% partial in maxillary molars. The incidence of isthmus in the mesiobuccal root of the maxillary first molars and in the mesial root of the mandibular first molars was high, particularly in sections 3-5 mm from the apex. Cleaning the isthmus is a major challenge during root canal treatment.

Effect of streptozotocin-induced diabetes mellitus on alveolar bone deposition in the rat

Effects of diabetes on alveolar bone remodelling were assessed by quantitative histology and a chronological lead-labelling technique. Experimental diabetes was induced by a single dose of 40 mg/kg of streptozotocin. Remodelling of the alveolar wall surrounding the root of mandibular first molar was studied in control rats fed ad libitum, and in diabetic and insulin-treated diabetic rats 24 days after the induction of diabetes. The volumes of bone formation on the mesial side of the alveolar wall were evaluated over a 10-day period by chronological lead-labelling and computer image analysis. For a histometric measure of bone-resorption, the number of osteoclasts along the distal surface of the alveolar wall was counted. The volume of bone formed and the number of osteoclasts were significantly lower in the diabetic rats than in the controls, but insulin treatment of diabetic rats normalised these histomorphometric measures of bone turnover. These results demonstrate that streptozotocin-induced diabetes mellitus reduces the rate of bone turnover in the alveolar wall surrounding the root, which reduction is corrected by treatment with insulin.

A retrospective study of endodontically treated mandibular first molars in a Chinese population

The purpose of this investigation was to study the prevalence of three roots and four root canals in the mandibular first molars of a Chinese population. A total of 832 cases of mandibular first molars that had received root canal treatment clinically were examined by reviewing the clinical records and radiographs. The results showed that: (a) Mandibular first molars with four root canals occur at a frequency of 31.5%. (b) More than two-thirds (68.3%) of the above cases had the fourth canal arising from the third root, an extradistal root. (c) The bilateral occurrence of this extradistal root in mandibular first molars was 67%. In conclusion, the occurrence of four root canals in mandibular first molars among Chinese people was not unusual.

Thickness of cementum/dentin in mesial roots of mandibular first molars

The mesial roots of 15 human first lower molars, along with the corresponding half of the tooth crown, were studied to determine the thickness of dentin-cementum. A device was developed whereby these could be embedded in resin with a precisely known orientation in space. The roots were radiographed in mesiodistal and vestibular-lingual projections, then sectioned perpendicular to the canal axis in the coronal third. Thickness of dentin-cementum was compared on sections and radiograms; results showed that the amount of hard tissue is effectively about one fifth less than that appearing on the radiogram.