Concurrent relationship between additional canals of mandibular first molars and maxillary first molars using cone-beam computed tomography

Objective

To investigate the bilateral concurrence and relationships between distolingual (DL) roots and DL canals of the mandibular first molars and second mesiobuccal (MB2) canals of the maxillary first molars using cone-beam computed tomography (CBCT).

Methods

A total of 150 CBCT images showing all mandibular and maxillary first molars were retrospectively investigated in a South Korean subpopulation. The patient age, sex, positions of first molars, and presence of roots and canals were assessed. The frequency, bilateral concurrence of DL roots, DL canals, and MB2 canals, and concurrent relationship of DL roots or DL canals with MB2 canals were investigated. Data were analyzed using Fisher’s exact test and odds ratios from binary logistic regression.

Results

The prevalences of DL roots, DL canals, and MB2 canals were 24.7, 42.7, and 56.0 %, respectively, and showed significant bilateral concurrence. A concurrent relationship between DL roots and MB2 canals was not demonstrated, whereas the presence of a DL canal was significantly correlated with the presence of an MB2 canal on the same side.

Conclusions

The presence of a DL root of the mandibular first molar, a strong ethnic characteristic, could not predict the presence of an MB2 canal of the maxillary first molar. The correlation between DL canals and MB2 canals on the same side and the significant bilateral concurrence, whether present or absent, of DL roots, DL canals, and MB2 canals can aid clinicians in the prediction of additional canals in the first molars.     

Furcation topography of the maxillary and mandibular first molars

The objective of the present study was to describe the topography of the furcation area of the maxillary and mandibular first molars. By using a photogrammetric method, the furcation areas of extracted teeth were plotted to obtain 3-dimensional contour maps. By comparing the individual 10 drawings of the maxillary and mandibular first molars, respectively, some morphological characteristics of the furcation areas could be described. Accordingly, the study showed the complexity of the furcation areas with presence of a number of small ridges, peaks and pits forming a mixture of convexities and concavities.     

上颌第一磨牙倾斜度自然代偿的最主要影响因素研究

目的 探寻未经治疗状态下错(牙合)患者上颌第一磨牙倾斜度(UM/PP)自然代偿的最主要因素.方法 共纳入1403例患者,涉及36个变量,以UM/PP为因变量进行多元回归分析,建立相应的变量影响权重解释模型.结果 治疗前上颌第一磨牙近远中倾斜度的回归模型纳入16个有意义的变量,包括年龄、是否双颌前突、安氏分类、垂直骨型、覆(牙合)覆盖以及部分头影测量变量等,可解释56.5%的变异.排名前三位的影响因素分别为SNB角(Beta值0.690),下颌第一磨牙萌出高度(Beta值0.481)及上颌第一磨牙萌出高度(Beta值0.423).结论 自然发育状态UM/PP影响因素回归模型中,SNB角、下颌第一磨牙萌出高度和上颌第一磨牙萌出高度是其中最主要的影响因素;其中SNB角对UM/PP影响最大,下颌越后缩,上颌第一磨牙越代偿性后倾.     

C-shaped root canal configuration in maxillary first molars

AIM: This clinical report presents the endodontic treatment of two maxillary first molars and the anatomical study of two additional maxillary first molars with a C-shaped distally located root canal system. This configuration is not a common finding. SUMMARY: According to the endodontic literature, the C-shaped root canal is most frequently seen in the mandibular second molar. The occurrence of C-shapes in maxillary first molars, however, has only been described in a limited number of case reports. We observed this configuration in two out of 2175 root-filled maxillary first molars treated at the Department of Endodontology, Ghent University Hospital, during the last 10 years. In order to study and visualize this particular aberration, cross-sections in two additional two-rooted maxillary first molars were made. From these cross sections it can be concluded that the C-shaped canal configuration is the result of a fusion of the distobuccal and the palatal roots.     

Root canal systems of the mandibular and maxillary first permanent molar teeth of south Asian Pakistanis

AIM: The purpose of the present ex vivo study was to investigate variations in the root canal systems of mandibular and maxillary first permanent molar teeth of South Asian Pakistanis. METHODOLOGY: The root canal systems of a sample of 30 mandibular and 30 maxillary first permanent molar teeth extracted from South Asian Pakistanis were studied using a clearing technique. RESULTS: The mesial roots of the mandibular molar teeth typically presented with two canals (97%) of type II, IV or VI configuration. The distal roots of these teeth presented with a single canal (50%) of type I or V configuration or with two canals (50%) of type II, IV or VI. The prevalence of four root canals in two-rooted mandibular first permanent molar teeth was 47%. In maxillary molar teeth the mesial roots with a single canal (47%) were type I or type V; those with two canals (53%) were type II, IV or type VI. The distal and palatal roots that presented as a single canal (100%) were type I or type V configuration. The prevalence of four root canals in three-rooted maxillary first permanent molar teeth was 53%. CONCLUSION: It is concluded that four root canals in mandibular and maxillary first permanent molar teeth of South Asian Pakistanis is a common occurrence. The distribution of the different configurations of root canal systems in this population differed from that in Caucasian groups, suggesting that variations in root canal systems may be attributed to racial divergence.     

Autotransplantation of maxillary second premolars to mandibular recipient sites where the primary second molars were impacted,predisposes for complications

Abstract

Objective. The aim of the study was to elucidate whether ankylosis of a transplanted permanent tooth can be predicted based on an evaluation of the primary and permanent dentitions. Materials and methods. The study comprised 162 maxillary second premolars and 49 third molars transplanted to the mandibular second premolar region in 157 patients treated in the period 1980–2003. Selection criteria: panoramic radiograph available; agenesis of the mandibular permanent premolar/s; persistence of the primary molar at the recipient site. The 211 transplanted teeth were observed for a period of between 1–29 years. Results. Seven per cent (95% confidence interval, CI = 3–11%) of the transplanted second premolars ankylosed during the first 10 years after operation. The success rate for transplantation of the third molar to the mandibular second premolar region was significantly lower (p = 0.001), as 40% (95% CI = 24–57%) of the third molars had ankylosed 10 years after operation. A significant association (p = 0.022) was found between ankylosis of a second premolar and infra-position of the primary second molar located at the recipient site. The infraposition group had 13% (CI = 4–23%) ankylosis after 10 year, whereas the non-infraposition group had 5% (CI = 1–9%) ankylosis after 10 years. Conclusions. The present study concludes that there is an increased risk of ankylosis of the transplanted permanent tooth if the primary tooth at the recipient site is in infraposition. This observation may be decisive for treatment planning, especially in young individuals in whom excessive growth of the alveolar process is expected from the cephalometric analysis.     

Root canal morphology of human maxillary and mandibular third molars

The anatomy of third molars has been described as unpredictable. However restorative, prosthetic, and orthodontic considerations often require endodontic treatment of third molars in order for them to be retained as functional components of the dental arch. The purpose of this study was to investigate and characterize the anatomy of maxillary and mandibular third molars. One hundred fifty maxillary and 150 mandibular extracted third molars were vacuum-injected with dye, decalcified, and made transparent. The anatomy of the root canal system was then recorded. Seventeen percent of mandibular molars had one root (40% of which contained two canals), 77% had two roots, 5% had three roots, and 1% had four roots. Teeth with two roots exhibited highly variable canal morphology, containing from one to six canals, including 2.2% that were "C-shaped." Fifteen percent of maxillary molars had one root, 32% had two roots, 45% had three roots, and 7% had four roots. Teeth with one root demonstrated the most unusual morphology, with the number of canals varying from one to six. An in vivo study of the canal morphology of treated third molars is suggested to provide the practitioner with an understanding of the clinical implications of third molar root anatomy.     

Totally submerged deciduous maxillary molars. Case reports

The total reimpaction or submersion of deciduous teeth is a very uncommon phenomenon and few cases have been reported in the literature. The condition affects the mandibular second deciduous molar most often and the maxillary first deciduous molar least often. Two cases of totally reimpacted maxillary deciduous molars are reported     

Association between ectopic eruption of maxillary canines and first molars

The purpose of this study was to elucidate a possible association between ectopic first molar eruption causing root resorption on the distal root of the primary maxillary second molar, and ectopic canine eruption causing root resorption on the permanent maxillary incisors.The subjects consisted of 30 patients, 22 females and eight males in the age range 8.3-15.0 years in whom root resorption of the permanent maxillary lateral and/or central incisor caused by the erupting permanent canine was diagnosed, and clinical and/or radiographic information concerning maxillary first molar eruption existed.It was found that of the 30 patients, seven (23.3 per cent) also had pathological root resorption of the second primary molar caused by ectopic molar eruption.It is suggested that patients with ectopic maxillary first molar eruption leading to pathological root resorption of the maxillary second primary molar are followed closely during the period of premolar and canine eruption, as the ectopic first molar could be an early warning of an increased risk of ectopic canine eruption leading to root resorption of the maxillary permanent incisors.     

Effect of groove placement on the retention/resistance of resin-bonded retainers for maxillary and mandibular second molars

STATEMENT OF PROBLEM: Lack of retention/resistance form in the clinical preparation of teeth for resin-bonded retainers may lead to clinical failure. PURPOSE: This study investigated the effect of proximal grooves on the retention/resistance of cast resin-bonded retainers for maxillary and mandibular second molar teeth. MATERIAL AND METHODS: Two ivorine teeth (a maxillary and a mandibular second molar) were prepared for resin-bonded retainers. Twenty metal replicas of the prepared teeth were made (10 for each tooth morphotype). Resin-bonded retainers 0.5 mm thick were made for the 40 replicas and luted with Panavia EX cement. Forces for dislodgment of the retainers were applied along the long axes of the teeth. Forces recorded at the time of dislodgment were analyzed with 2-way analysis of variance and the post hoc Scheffé test. RESULTS: Grooves resulted in substantial increases in debonding forces for maxillary molars (P<.001). The effect of grooves on mandibular second molars was not significant (P=.13). CONCLUSION: Grooves placed in tooth preparations of maxillary molar teeth for resin-bonded retainers had a significant effect on retention/resistance. The effect of grooves on mandibular second molars was less pronounced.     

下颌第一恒磨牙远舌根的临床分析

目的调查下颌第一恒磨牙远舌根的发生率及根管治疗情况。方法临床收集378颗下颌第一恒磨牙根管治疗的完整病例,包括病历记录和术前、术中、术后X线片,记录下颌第一恒磨牙的牙根数目、根管数目及根管治疗情况。结果在378颗下颌第一恒磨牙中,远舌根的发生率为26.98％（102/378）,男、女患者和左、右侧远舌根的发生率均无统计学差异（P>0.05）。在根管治疗中,远舌根根管器械分离、侧穿和欠填的发生率高于其他根管（P<0.05）。结论远舌根在下颌第一恒磨牙中的发生率较高,发生器械分离、根管侧穿以及欠填的比例也高于其他根管。     

Bilateral maxillary and mandibular fourth molars: a case report and literature review

Supernumerary teeth are those present in addition to the normal set of teeth. These teeth are found in both the primary and the permanent dentitions, and are most frequently seen in the maxillary anterior and molar regions. Supernumerary molars are divided into two types, depending on their location: distomolars and paramolars. Distomolars usually occur in the form of a fourth molar distal to the third molar, while paramolars are rudimentary supernumerary teeth that might develop buccally or lingually to the molar series. The management of a supernumerary tooth should be part of a comprehensive treatment plan. This paper reports a rare case of a male patient with bilateral maxillary and mandibular fourth molars, and reviews the literature on supernumerary teeth.     

Treatment of a Class II, Division 1, malocclusion with the extraction of maxillary canines and mandibular first premolars.

This is the case report of a patient whose healthy but malformed maxillary canines and normal mandibular first premolars were extracted in order to correct a Class II, Division 1, malocclusion. Maxillary premolars were substituted for the extracted canines.     

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

AIM: 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. METHODOLOGY: 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. RESULTS: 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. CONCLUSIONS: 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.     

Ectopic eruption of the maxillary central permanent incisors and mandibular first permanent molars: report of an unusual case.

Ectopic eruption is a disturbance in which the tooth does not follow its usual course. Among its more important etiologic factors are macrodontism, shortened arch length, posterior positioning of the maxilla, atypical eruption angle, and genetic factors. This article reports a rare case of ectopic eruption of 4 permanent teeth, maxillary central incisors and mandibular first molars, in a child aged 7 years and 11 months, in which the treatment consisted of extracting the maxillary primary central incisors and making an orthodontic intervention on the mandibular arch. A bilateral fixed appliance containing 2 hooks with loops, 1 buccal and the other lingual, was placed on the mandibular primary first molars. The hooks were activated in a niche made of light-curing resin on the occlusal surface of the mandibular permanent molars, to bring about the distal drift of these teeth. After 6 months, complete eruption of the mandibular permanent molars occurred, and a slight displacement of the maxillary permanent central incisors toward the median line was noted. The importance of early, adequate treatment is discussed.     

Root canal anatomy of maxillary first and second permanent molars

AIM: The aim of this investigation was to study the root canal anatomy of maxillary first and second molar teeth from an Irish population sample using a clearing technique. METHODOLOGY: Eighty-three extracted permanent maxillary right first molars and 40 permanent right maxillary second molars were included in this investigation. The specimens were demineralized and then cleared using methyl salicylate. The following observations were made: number of roots, prevalence of fusion, types of root canals using Vertucci's classification, presence and position of lateral canals, presence and position of transverse anastomoses, number and position of apical foramina and the frequency of occurrence of apical deltas. RESULTS: Eleven per cent of maxillary first molars and 43% of maxillary second molars had fused roots. A total of 78% of mesiobuccal roots in maxillary first and 58% in maxillary second molars had two canals. Sixty-two per cent of maxillary first and 50% of maxillary second molars had two apical foramina. There was a significant inverse relationship between age and the occurrence of two canals and between age and the occurrence of transverse anastomoses in both tooth morphotypes (P < or = 0.05). CONCLUSIONS: It is concluded that a significant proportion of the first and second molar specimens studied had two canals in the mesiobuccal root (78% and 58%, respectively) and that the occurrence of two canals and transverse anastomoses decreased significantly with increasing age.     

Impacted permanent first molars: two case reports

Impaction of first permanent molars is an uncommon condition and few cases are reported in the literature. Two cases of a mandibular and a maxillary impacted first permanent molar are presented, their aetiology and treatment alternatives are discussed.     

上颌第一乳磨牙临床牙冠的计算机辅助测量

目的:收集华北地区上颌第一乳磨牙形态数据,分析其形态特征。方法:使用3d扫描仪对116名儿童重建上颌第一乳磨牙,使用Creo 2.0测量软件测量牙冠最大近远中径、颊舌径、冠指数、冠面积、冠周径、冠高等。结果:获得了华北地区上颌第一乳磨牙冠周径频数表和各检测项医学参考值范围。最大近远中径、颊舌径、冠面积、颌面周径、最大周径男性大于女性(P<0.05),左右两侧各检测项差异均无统计学意义(P>0.05)。结论:该研究提供了更适合中国北方儿童第一乳磨牙形态的基础数据。     

Protraction of mandibular second and third molars into missing first molar spaces for a patient with an anterior open bite and anterior spacing

In a young woman, aged 18 years 8 months, who had an anterior open bite and anterior spacing, the right and left mandibular first molar extraction spaces were closed by protraction of the second and third molars without reciprocal retraction of the incisors and the premolars. The amounts of protraction for the second molars were 12 mm on the right side and 11 mm on the left side. Two miniscrews were inserted into the mesiobuccal side of the edentulous spaces, and 2 more screws were inserted into the anterior sites after removing previous miniscrews. In addition, 4 miniscrews were inserted into the buccal and palatal sides between the first and second maxillary molars to intrude the maxillary posterior teeth, which had extruded into the missing mandibular spaces. Careful biomechanical consideration was used to prevent extrusion of the molars and worsening of the anterior open bite from protraction of the posterior teeth. Ultimately, the anterior open bite was corrected by both intrusion of the maxillary molars and extrusion of the maxillary anterior teeth. Excellent occlusion and correction of the anterior open bite were achieved without tipping, rotation of the posterior teeth, or other problems. The right mandibular third molar, which had been impacted at the beginning of treatment, erupted into the second molar space and functioned properly. At the 1-year follow-up examination, the patient had a slight anterior open bite, but closure of the first molar extraction spaces was well maintained.     

An occlusal and cephalometric analysis of maxillary first and second premolar extraction effects

The purpose of this study was to examine dimensional changes in the maxillary arch following the extractions of maxillary first or second premolars. Pre- and posttreatment records of 71 patients treated by one experienced orthodontist were randomly selected from completed premolar extraction cases. Forty-five patients involved the extraction of maxillary first premolars; of these, 15 also had extractions of mandibular first premolars and 30 had extractions of mandibular second premolars. Twenty-six patients involved the extraction of maxillary second premolars, and all of these also had extractions of mandibular second premolars. Pretreatment factors that seemed to suggest a basis for the extraction choice in this sample included incisal overjet, molar relationship, and maxillary incisor protrusion. Mean reductions with treatment in the anteroposterior arch dimension were similar within all premolar extraction groups. There was evidence of greater mean maxillary intermolar-width reduction following the extractions of maxillary second premolars than following extractions of maxillary first premolars. Greater mean maxillary incisor retraction was found in the maxillary first premolar extraction group than in the maxillary second premolar group. A wide range of individual variation in incisor and molar changes did, however, accompany treatment involving both maxillary premolar extraction sequences.