Mandibular first molar with six separate canals

Introduction

Many anatomical variations can occur within the mandibular first molar. Commonly, 3-4 canals are located, but as many as 6-7 canals have been reported.

Methods

This report describes a case of a mandibular first molar with 6 separate canals (3 mesial and 3 distal) that was instrumented with conventional hand and rotary files and obturated by using a hybrid warm vertical compaction technique.

Results

Recall examination as far as 3 years post-treatment found no sensitivity to percussion or palpation and recall radiographs after treatment show resolution of the previous apical periodontitis.

Conclusions

The existence of such teeth as these underlies the importance of looking for additional canals.     

Mandibular first molar with three distal canals

A mandibular molar requiring root canal therapy was found with five canals, a mesial root, and two distal roots. The distobuccal root had two separate canals, and the distolingual root had but one. The bizarre aspects of this case are somewhat lessened because of the presence of the second distal root. Practitioners should not become excessively alarmed by the increasing reports of bizarre pulpal anatomy. However, knowledge of their existence may occasionally enable them to treat a case successfully that otherwise might have ended in failure.     

Mandibular first molar with four distal canals

A mandibular first molar with more than four canals is an interesting example of anatomic variations, especially when four of these canals are located in distal roots. This report describes a case of a mandibular first molar with six canals (two mesial and four distal canals in two distal roots). The canals were equipped with a K-file and irrigated with NaOCl (5.25%) and normal saline as the final irrigant. The canals were filled laterally with gutta percha and AH26 sealer (De Trey, Dentsply, Switzerland). This case shows a rare anatomic configuration and points out the importance of looking for additional canals.     

Mandibular first molar with three distal root canals

CASE REPORT: A right mandibular first molar requiring root canal treatment was found to have one mesial and two distal roots and a total of five canals. The mesial and distobuccal root had two separate canals; the distolingual root had one. This case demonstrates a rare anatomical configuration and supplements previous reports of the existence of such configurations in mandibular first molars.     

Mandibular rotation and lower face height indicators

Lower face height indicators and mandibular rotation are assessed at 7 and 12 years of age in a sample of 46 children, comparing the corpus axis and mandibular plane as indicators of change in mandibular position. The parameters involving the mandibular plane consistently show higher correlations.     

Mandibular third molar space in different antero-posterior skeletal patterns

Retromolar space has long been identified as a major factor in the aetiology of mandibular third molar impaction. The aims of this study were to compare mandibular third molar space between the different antero-posterior (A-P) skeletal patterns, between erupted and impacted third molars in the different A-P skeletal patterns, and to report on the status of third molar eruption/impaction among the studied subjects. A total of 432 mandibular third molars in 270 subjects (132 females and 138 males) were investigated from dental pantomograms (DPTs) and lateral cephalograms (LC). The average age for the total sample was 20.80 ± 2.03 years. The subjects were divided into three groups according to their ANB angle as follows: skeletal Class I (144 third molars in 90 subjects), skeletal Class II (145 third molars in 95 subjects), and skeletal Class III (143 third molars in 85 subjects). Each group was subdivided into impacted and erupted subgroups. DPT and LC were traced and the following variables were measured: retromolar space width, third molar width and angulation, β angle, second molar angulation, mandibular length, and gonial angle. Independent t-test, analysis of variance, and chi-square test were used for statistical analysis. Retromolar space width in the Class III subjects was smaller than in the Class I subjects (P?相似文献   

A submerging lower first permanent molar

A girl of 12 years with a submerging lower first permanent molar which was successfully treated is described. The relevant literature is briefly discussed.     

前倾阻生的下颌第三磨牙在下颌第一恒磨牙缺失时的矫正

目的　为代偿下颌第一恒磨牙的缺失 ,将下颌第二、三磨牙前移到原第一、二磨牙的位置后 ,再将前倾阻生的第三磨牙矫正到正常位置并发挥正常功能。方法　用方丝弓固定矫治器将第二、三磨牙前移到第一、二磨牙的位置 ,再后推第三磨牙 ,解除第二磨牙对其的阻生 ,最后 ,后倾竖直该牙。结果　 9例前倾阻生的下颌第三磨牙在第一恒磨牙缺失时 ,通过该方法矫治 ,均成功地使第三磨牙竖直到正常位置。结论　下颌第一恒磨牙缺失后 ,可用矫正的方法使第二、三磨牙前移 ,分别代替原第一、二磨牙 ,前倾阻生的第三磨牙可以矫正     

Mandibular third molar eruption in relation to available space as assessed on lateral cephalograms

It has previously been suggested that the distance between the Xi point (Ricketts 1972) and the distal aspect of the mandibular second molar (M2), measured on lateral cephalometric head films, should be at least 25 mm by adulthood to allow for the normal eruption of the third molars (M3s) in the lower jaw. It was the aim of this investigation to test the validity of this statement in two groups of young adults (mean age 25 years). The individuals in the first group had complete dentitions including M3s in good occlusions. In the second group all M3s had been extracted due to failure to erupt. Mandibular length and morphology and the dimension of the ramus was also studied in the same material. All measurements were made on standard lateral head films. The distance Xi-M2 was found to be significantly greater in individuals with complete dentitions as compared with individuals who had impacted M3s. Furthermore, this variable exhibited significantly greater values in males than in females in both investigation groups. However, in nearly fifty per cent of the subjects with complete dentitions, the M3s had erupted despite a Xi-M2 distance of less than 25 mm. Mandibular length in males was significantly greater in the complete group than in the extraction group. In females no such difference was recorded. The angular measurements used in this study did not differ significantly between the complete and the extraction groups.     

Mandibular first and second molar tooth transposition: a case report

A case is reported of what appears to be a transposition affecting the mandibular first, second, and third molars. The possible aetiology is discussed in relation to previously published studies. In the case described the primary actilogical factor appears to intraosseous migration of the developing tooth germ.     

Mandibular first premolar teeth extraction in skeletal Class III malocclusion

The patient was a 12-year-old girl with a skeletal class III malocclusion characterized by mandibular protrusion, a high mandibular plane angle, severe negative overjet and deep overbite. The patient's mandibular first premolar teeth were extracted following the standards of edgewise mechanotherapy. The total active treatment time was 19 months, however, retention was needed until the patient was 19 years old. The malocclusion has been treated satisfactorily resulting in correction of the functional and esthetic flaws without orthognatic surgery.     

下颌第一恒磨牙C形根管2例

下颌第一恒磨牙根管系统复杂多样,其中C形根管较为少见。本文报道2种不同类型的下颌第一恒磨牙C形根管病例。病例1,一个完整C形融合牙根,根管特点为近中舌侧位置一个根管,C形态的峡部及远中位置融合为一个根管。病例2,颊侧一个C形态融合牙根和远中舌侧一个独立牙根,根管特点为颊侧C形态区域为Ⅱ-Ⅰ型根管和一个独立的远中舌侧根管。     

External invasive resorption in a three-rooted lower first molar

Several pathoses can be present concurrently in one tooth, and if that tooth has an unusual anatomical variation, the diagnosis and treatment can be further complicated. This case stresses the importance of accurate assessment and diagnosis prior to intervention and their role in identifying cases for referral to a specialist in today's increasingly litigious environment.     

Orthodontic space closure after first molar extraction without skeletal anchorage

Objective

The aim of the study was an analysis of effects and side-effects during mesialization of second molars after extraction of the first permanent molars using the anterior dentition/premolars (PM) as an anchorage unit.

Patients and methods

A total of 35 patients were examined retrospectively who had undergone unilateral or bilateral first permanent molar extraction in the upper or lower arch due to carious lesions. Space closure was carried out in all cases through mesialization of the second molar using an elastic chain fixed to an edgewise stainless steel archwire and tying the anterior dentition/PM together with a continuous laceback ligature. Tooth movement was assessed from lateral cephalograms, orthopantomograms (OPGs) and images of the patient??s study casts taken before and after the end of therapy.

Results

Space closure after first molar extractions by mesialization of the second molars without skeletal anchorage was largely achieved by bodily forward movement of the teeth, including a small tipping component or tooth-uprighting component when molars were already mesially inclined. Unilateral and bilateral mesialization of the second molars led to retrusion in the maxilla and mandible [(?incl.=?3.6° (max., bil.), ?incl.=?4.2° (mand., bil.)] and to translational retraction [(?s=?2.3?mm (max., bil.), ?s=?1.6?mm (mand., bil.)] of the incisors. Examination of the soft tissues revealed an increased posterior displacement of the upper and lower lips to the esthetic line [(?s=?2.8?mm (max. bil.), ?s=?2.2?mm (mand., bil.)]. In cases of unilateral mesialization less than 50% of the patients had a slight midline deviation in the mandible towards the extraction side.

Conclusion

Side effects during mesialization of the second molars without skeletal anchorage in the anterior dentition/PM were observed primarily affecting the incisors integrated into the anterior anchorage unit. These side-effects resulted in posterior displacement of the soft tissues, including a change in profile. This must be taken into consideration when taking this therapeutic approach.