Asymmetric Extraction for Managing a Severely Crowded Malocclusion: A Case Report

The mandibular premolar impactions account for nearly 24% of all the dental impactions including the third molars. The literatureregarding the impactions of mandibular premolars is very limited although they are considered as the third most commonimpactions after all the third molars and maxillary canines. This case report describes the treatment of a Class I malocclusionhaving severe crowding in both the upper and lower arches, buccally placed maxillary canines and impacted mandibular rightsecond premolar with an asymmetric treatment approach in a young growing patient.

Sealing Ability of Gutta-percha in Apical Area and Degree of Tugback Sensation after Root Canal Preparation-In Vitro Study

Aims The aim of this study was to evaluate the degree of tug-back after root canal preparation with respect to the gutta-percha-occupied area (GPOA). Materials and Methods Roots of 50 mandibular premolar teeth were prepared till size 35/0.04, then gutta-percha (GP) cones of same size and taper were adapted to root canals, and the degree of tug-back sensation was scored as loose, slight, adequate and strong. Root canals were filled with GP and AH26 sealer, and then sectioned horizontally 1 mm from the apical end at three levels. GPOA and its sum from the three levels sum of GPOA (sGPOA%) were calculated using stereomicroscope. Statistical Analysis At each sectioned level, GPOA% was compared with the score of tug-back sensation using one-way ANOVA [Analysis of variance] at a 5% significance level. Multiple pair wise comparisons were performed using Tukey test. Results Tug-back sensation was present in all canals, described as slight, adequate and strong in 4, 8 and 8 canals, respectively. Among the tug-back scores, quantitative analyses of GPOA% showed significant differences at 1-and 2-mm levels. The strong tug-back with sGPOA of 76.5 ± 11.1% was significantly higher than that of slight tug-back. Conclusions Under the conditions of this study, the tug-back scoring system can be applied to determine the amount of GP adaptation inside the root canal.

Effect of ferrule on the fracture resistance of mandibular premolars with prefabricated posts and cores

PURPOSE: This study evaluated fracture resistance with regard to ferrule lengths and post reinforcement on endodontically treated mandibular premolars incorporating a prefabricated post and resin core. MATERIALS AND METHODS: One hundred extracted mandibular premolars were randomly divided into 5 groups (n=20): intact teeth (NR); endodontically treated teeth (ETT) without post (NP); ETT restored with a prefabricated post with ferrule lengths of either 0 mm (F0), 1 mm (F1), or 2 mm (F2). Prepared teeth were restored with metal crowns. A thermal cycling test was performed for 1,000 cycles. Loading was applied at an angle of 135 degrees to the axis of the tooth using a universal testing machine with a crosshead speed of 2.54 mm/min. Fracture loads were analyzed by one-way ANOVA and Tukey HSD test using a statistical program (α=.05). RESULTS: There were statistical differences in fracture loads among groups (P<.001). The fracture load of F2 (237.7 ± 83.4) was significantly higher than those of NP (155.6 ± 74.3 N), F0 (98.8 ± 43.3 N), and F1 (152.8 ± 78.5 N) (P=.011, P<.001, and P=.008, respectively). CONCLUSION: Fracture resistance of ETT depends on the length of the ferrule, as shown by the significantly increased fracture resistance in the 2 mm ferrule group (F2) compared to the groups with shorter ferrule lengths (F0, F1) and without post (NP).

The efficacy of ultrasonic irrigation technique on debris removal during root canal treatment

PURPOSE: The purpose of this study was comparing the efficacy of passive irrigation (PI) and passive ultrasonic irrigation (PUI) for ability to remove debriment of canals. MATERIALS AND METHODS: Mandibular premolars were decoronated and standardized to 16 mm length. After root canal enlargement and half separating longitudinally, standardized groove of 4 mm length, 0.2 mm width and 0.5 mm depth were formed on the dentin wall of one half. Three depressions in the canal wall of the opposite half, 0.3 mm in diameter and 0.5 mm in depth, were formed. After each groove and depression was filled with dentin debris, two sections of each half were reassembled using impression putty material. In group 1 the canals were irrigated with 2.5% NaOCl by PI. In group 2 the canals were irrigated with 2.5% NaOCl by PUI. Before and after root canal irrigation, the root canal wall of the section was taken with a microscope and a digital camera as images. The amount of dentin debris remaining in grooves and depressions was assessed using a scoring system. RESULTS: There was no significant difference between PI and PUI except for the middle 1/3 of the root canal (P = 0.004). CONCLUSION: At the middle 1/3 of the root canal, PUI removed more dentine debris than PI. But the removal efficiency of dentin debris is not significantly different between the PUI and PI at the apical area of root canal in mandibular premolars.

A comparison of the fracture resistances of endodontically treated mandibular premolars restored with endocrowns and glass fiber post-core retained conventional crowns

PURPOSE: This in-vitro study aimed to evaluate the fracture resistances and failure modes of endodontically treated mandibular premolars restored with endocrowns and conventional post-core retained crowns. MATERIALS AND METHODS: Thirty mandibular premolars were assigned into three groups (n=10): GI, intact teeth; GE, teeth with endocrowns; GC, teeth with conventional post-core supported crowns. Except for the teeth in group GI, all specimens were cut to 1.5 mm above the cementoenamel junction and endodontically treated. Both endocrowns and conventional crowns were fabricated from lithium-disilicate blocks using a CEREC 3D CAD/CAM unit. All specimens were subjected to thermocycling and then to 45° oblique compressive load until fracture occurred. The fracture resistance and failure mode of each specimen were recorded. Data were analyzed with one-way ANOVA and LSD Post Hoc Test (α=.05). RESULTS: The fracture resistances of GE and GC were significantly lower than that of GI (P<.01), while no significant difference was found between GE and GC (P=.702). As of the failure mode, most of the specimens in GE and GC were unfavorable while a higher occurrence of favorable failure mode was presented in GI. CONCLUSION: For the restoration of mandibular premolar, endocrown shows no advantage in fracture resistance when compared with the conventional method. Both of the two methods cannot rehabilitate endodontically treated teeth with the same fracture resistances that intact mandibular premolars have.

Occlusal Surface Analysis of Mandibular Premolars in Koreans / 체질인류학회지

The aim of this study was to investigate the characteristics of mandibular premolars regarding size and morphology in Koreans. Moreover, comparisons of gender difference in mandibular premolars were examined to expand anatomical database in Koreans. Data was obtained from students in School of Dentistry, Chonnam National University, Gwangju, Korea. The total number of participants was 66 (33 men and 33 women) and dental casts were fabricated. A total of nine items was investigated using a digital measuring software. Five measurements were performed including intercuspal distance (ID), buccolingual diameter (BL), mesiodistal diameter (MD), total crown area, and each cusp area. One item as each cusp area ratio was calculated, and three items were observed including the number of lingual cusp, occlusal groove patterns, and mesiolingual developmental groove. Comparison measurements were analyzed using paired t-tests, independent t-tests and Pearson correlation tests. Average values in mandibular second premolars were larger than first premolars in most of measurements with a significance with the exception of mesiodistal diameter (p=0.223). Overall average values were significantly higher in male than in female except intercuspal distance (p=0.607) and lingual cusp area (p=0.070) in mandibular premolars. The presence of mesiolingual developmental grooves in the first premolars was 59.1% (male 51.5%, female 66.7%). The most common occlusal groove patterns of the second premolar were a Y pattern, followed in order by H and U patterns. These results provide valuable morphological characteristics of mandibular premolars in Koreans.

The Use of Dentascan to Diagnose and Treat Mandibular Premolar with Multiple Canals.

Introduction: For successful endodontic therapy it is vital to have thorough knowledge of morphology of the root canal system and its variations besides proficient aseptic intraoperative condition. Mandibular second premolars are usually single rooted tooth with single root canal system. The incidence of the number of roots and the number of canals varies greatly in the literature. Methods and Results: This case report describes an unusual case of mandibular second premolar with two roots and five root canals. This was confirmed by radiographs, dentascan and dental operating microscope (DOM), and was successfully treated using K files system, guttapercha and AH plus sealer in lateral condensation manner. Conclusion: The clinical significance of this case report is that the precise awareness about the aberrant morphologies of the root canal system can only be appreciated when advanced radiographic techniques, magnification and illumination are used to treat such type of cases.

Differences in the mandibular premolar positions in Angle Class I subjects with different vertical facial types: A cone-beam computed tomography study / 대한치과교정학회지

OBJECTIVE: To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment. METHODS: Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured. RESULTS: The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type. CONCLUSIONS: There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.

Management of Type III Dens Invaginatus in a Mandibular Premolar: A Case Report

Dens invaginatus is a well-known malformation of teeth, which probably results from an invagination of enamel organ into dental papilla during tooth development. The endodontic treatment of invaginated teeth may be challenging due to difficulties in accessing the root canals and also due to complex variations of internal morphology. This article presents the endodontic management and follow-up in a rare case of right mandibular second premolar with Oehlers' type III dens invaginatus. The result of cold pulp testing was positive for this tooth but it was associated to a sinus tract and periapical lesion. Herein, it is described the root canal therapy of this tooth combined with periapical surgery, emphasizing the importance of proper diagnosis and planning by using cone beam computed tomography (CBCT). This case report presents the proper periapical healing 6 months after the combination of nonsurgical and surgical treatments. It also shows that CBCT is an important auxiliary examination to avoid errors in diagnosis and subsequent treatment of dental anomalies.

Dens invaginatus é uma malformação dentária já bem reconhecida, que provavelmente resulta de uma invaginação do órgão do esmalte para dentro da papila dentária durante o desenvolvimento do dente em questão. O tratamento endodôntico de dentes invaginados pode ser um desafio devido às dificuldades de acesso aos canais radiculares e também devido à complexidade da morfologia interna. Este artigo apresenta o manejo endodôntico e o acompanhamento de um caso raro de segundo pré-molar inferior direito com dens invaginatus Tipo III de Oehlers. O resultado do teste de sensibilidade pulpar ao frio foi positivo para este dente, mas o mesmo estava associado a uma fístula e lesão periapical. Relata-se o tratamento de canal deste dente associado à cirurgia periapical, enfatizando a importância de um correto diagnóstico e plano de tratamento, utilizando a tomografia computadorizada de feixe cônico (TCFC). Este relato de caso mostra reparo periapical adequado 6 meses após a combinação dos tratamentos não-cirúrgico e cirúrgico. Mostra também que a TCFC é um importante exame auxiliar para evitar erros no diagnóstico e posterior tratamento de anomalias dentárias.

Endodontic retreatment - unusual anatomy of a maxillary second and mandibular first premolar: Report of two cases.

An accurate diagnosis of the morphology of the root canal system is a prerequisite for successful root canal treatment. A major cause of endodontic treatment failure in missed (or) untreated root canals is that they still harbor infection. Careful radiographic interpretation and examination of pulp chamber floors are helpful in locating root canal entrances. These case reports present anatomical variations in upper and lower premolars.

Morphometrical and morphological study of mental foramen in dry dentulous mandibles of South Andhra population of India.

Background: Mental foramen (MF) is an anatomical structure of particular importance in local anesthesia and surgical procedures in terms of achieving effective mandibular nerve blocks and avoiding injuries to the neurovascular bundles. Aim: To determine the morphometry and morphology of MF in south Andhra population of India, hitherto unreported. Materials and Methods: Ninety dry dentulous mandibles of both sexes were examined for position, size, shape and number of MF. Results: Various parameters investigated are, the horizontal distance between (1) symphysis menti and MF was 27.2 mm on right and 27.7 mm on the left, (2) MF and posterior border of ramus was 70.7 mm on both sides, vertical distance between (3) MF and inferior border of mandible was16.5 mm on right and 14.3 mm on left, (4) alveolar crest and MF was 13.7 mm on right and 16.4 on left, (5) distance between the MF and below the apex of premolar socket was +2.8 mm on right and +3.5 mm on left and above the socket was -2.8 mm on right and -2.7 mm on left. Occurrence of MF below the second premolar tooth was found to be highest (73.2%). Average size of MF was larger on left and its way of exit was in postero-superior direction. Shape of MF was round in 79% and oval in 21% and double MF was found in 8.9% of mandibles. Conclusions: In the present study, most common position of MF was found below the apex of second premolar in 73.2% and between the second premolar and first molar in 19% of mandibles. The other morphometrical findings of this study may be implicated by dental practitioners and maxillofacial surgeons.

Conservative management of mandibular second premolar impaction.

The mandibular second premolar is one of the most frequently impacted teeth. The recommended treatment is to extract the second primary molar with or without removing the bone along the eruption path, to uncover the tooth surgically and move it into the arch by orthodontic treatment. This paper reports the conservative management of an impacted left mandibular second premolar which exhibited self-correction and erupted into occlusion within 18 months. The purpose of this article is to review the principles of case management of impacted mandibular premolars and to illustrate their potential to respond well to treatment.

Scanning electron microscopic evaluation of the root apex of mandibular premolars

This aim of this study was to evaluate the root apex of mandibular premolars regarding the presence of main and accessory foramina. The root apexes from fifty extracted mandibular single-rooted premolars were examined by scanning electron microscopy (SEM). The apical openings had their diameter measured and were identified as main or accessory foramina. Double blinded and calibrated examiners analyzed the SEM photographs and classified the premolar roots into three types, based on the presence and size of the apical openings. Type I: roots with a single main apical foramen and no accessory foramina; type II: roots with a main foramen and one or more accessory foramina; type III: roots with accessory foramina only. For the first premolar, 16 roots were classified as type I (48.48%), 4 as type II (12.12%) and 13 as type III (39.40%). For the second premolars, 10 roots were classified as type I (58.83%), 3 as type II (17.65%) and 4 as type III (23.52%). The high incidence of roots with accessory foramina only (type III), mainly in the first premolar, warns of the need for caution during working length determination and apical debridement.

O objetivo deste estudo foi avaliar o apice radicular de premolares inferiores com relacao a presenca de forames ou foraminas. O apice radicular de cinquenta pre-molares unirradiculados humanos extraidos foram examinados pela microscopia eletronica de varredura (MEV). As aberturas apicais tiveram seus diametros medidos e foram identificados como forames ou foraminas. Dois examinadores calibrados e cegos quanto aos grupos analisaram as micrografias em MEV e classificaram as raizes dos pre-molares em tres tipos, baseadas na presenca e tamanho das aberturas apicais. Tipo I: raizes com um unico forame e nenhuma foramina; tipo II: raizes com um forame e uma ou mais foraminas; Tipo III: raizes somente com foramina. Para o primeiro pre-molar, 16 raizes foram classificadas como Tipo I (48.48%), 4 como tipo II (12.12%) e 13 como tipo III (39.40%). Para o segundo pre-molar, 10 raizes foram classificadas como tipo I (58.83%), 3 como tipo II (17.65%) e 4 como tipo III (23.52%). A alta incidencia de raizes do Tipo III, principalmente no primeiro pre-molar, alerta para a necessidade de cuidados na determinacao do comprimento de trabalho e exploracao foraminal.

Bilateral dens invaginatus in the mandibular premolar region.

Dens invaginatus (dens in dente, DI) is a rare developmental anomaly resulting from invagination of a portion of the crown rare. It is an important dental anomaly due to the possible pulpal involvement. DI can be detected clinically in a tooth presenting unusual crown morphology or having deep foramen coaceum. Also, clinically, non-suspected affected teeth are commonly diagnosed as an incidental radiographic finding. Presence of DI in the mandibular premolar teeth is unusual. Aims is to introduce a case of bilateral occurrence of DI in mandibular first premolar teeth. A 33- year-old man was referred to our clinic with a chief complaint of severe pain in his lower third molar tooth. Radiographic examination revealed bilateral DI (single at the left, double at the right) in mandibular first premolar teeth. The teeth were restored with fissure sealant. Although bilateral appearance of DI is a frequent situation, mandibular occurrence is very rare. Our review of the literature reveals just nine cases of DI, and only one of them is in a premolar tooth.