Root canal treatment of maxillary second molar with three mesial buccal root canals: a case report and literature review / 口腔疾病防治

Objective@#To explore the key points of clinical diagnosis and treatment of three mesiobuccal root canals.@*Methods@# In the procedure of endodontic therapy for the upper left second molar with pulpitis, through root canal exploration under a dental microscope and cone beam CT (CBCT)-assisted imaging examination, it was confirmed that the left upper second molar contained 3 roots and 5 root canals, among which the third root canal existed in the mesiobuccal root. Combined with perfect root canal preparation, cleaning, disinfection, filling and minimally invasive inlay repair, the clinical symptoms were eliminated. The patients were followed up and the related literatures were reviewed. @* Results @# One- and two-year follow-ups showed that the tooth had no discomfort and could be used normally. X-ray revealed that the filling was complete, and the periapical tissue was normal. The results of the literature review showed that the incidence of three mesiobuccal root canals in maxillary second molars was 0.11%-4.2%. It is difficult to find additional root canals only by X-ray imaging. Dentists should further determine the number and anatomical shape of root canals by CBCT and operating microscopy. When there are three mesiobuccal root canals in maxillary molars, dentists should avoid overpreparation. Healthy tooth tissue is the key to good prognosis. @* Conclusion@#During root canal therapy, clinicians should consider the anatomical variation of the root canal, should always be alert to the existence of an extra root canal, and should use CBCT, operating microscopy, ultrasound and various auxiliary instruments to locate and treat the variant root canal.

Comparison of diagnosing the relationship between the root of maxillary posterior tooth and maxillary sinus between panoramic radiography and cone beam computer tomography / 口腔疾病防治

Objective@#To study the diagnostic accuracy and the distance between the root of maxillary posterior tooth and the maxillary sinus using panoramic radiography and cone beam computer tomography; to provide basic information for clinicians to treat diseases in the maxillary posterior region. @* Methods@#Eighty patients were included in this study. A total of 671 specimens were measured for the distance between the root tip and the maxillary sinus floor in both imaging modalities.@*Results @#The roots that did not contact the sinus floor or contacted but did not project into the sinus cavity showed an agreement of 82% and 70% when using panoramic radiography. Forty-eight percent of the roots that projected into the sinus cavity in panoramic radiography showed protrusion into the sinus with cone beam computer tomography (CBCT). For panoramic radiography and CBCT showing root projections into the sinus cavity, the average distances were 2.19 ± 1.82 mm and 1.47 ± 1.01 mm, respectively. There was a significant difference between the two values (P ＜ 0.05).@*Conclusion@# Panoramic radiography is more accurate when roots of maxillary posterior teeth do not contact the sinus floor or contact it. However, it has a lower accuracy rate when the tooth roots protrude into the sinus.

The early treatment of buccoversion malpositon of maxillary second molars / 实用口腔医学杂志

The buccoversion malpositon of maxillary second molars is one kind of common malocclusion.It can lead to damages to stoma-tognathic system.The adjustable maxillary molar retractor is an effective tool in the early treatment of this kind of malposition.

Dilemmas pertaining to three canals in the mesiobuccal root of a maxillary second molar: a case report

The mesiobuccal root of the maxillary molars is well known to pose a hindrance during endodontic therapy. Presented here is a case of a maxillary left second molar where three canals were located in its mesiobuccal root with the use of visual and diagnostic aids. Difficulties encountered during the process of unveiling the tooth's internal anatomy were discussed. The dilemmas encountered pertained to the root canal configuration, the nomenclature of the extra canals, and the justification for the presence of a third canal. The root canal configuration of 3-2-1 was confirmed for the mesiobuccal root using information gained from clinical, radiographic, and multi-detector computed tomography (MDCT) scan findings. This case demonstrates the need for efforts to locate extra canals in the mesiobuccal root of the maxillary molars as their internal anatomy remains a mystery.

A study of the distobuccal root canal orifice of the maxillary second molars in Chinese individuals evaluated by cone-beam computed tomography

As is commonly understood, the root canal morphology of the maxillary molars is usually complex and variable. It is sometimes difficult to detect the distobuccal root canal orifice of a maxillary second molar with root canal treatment. No literature related to the distobuccal root canals of the maxillary second molars has been published. Objective: To investigate the position of the distobuccal root canal orifice of the maxillary second molars in a Chinese population using cone-beam computed tomography (CBCT). Material and methods: In total, 816 maxillary second molars from 408 patients were selected from a Chinese population and scanned using CBCT. The following information was recorded: (1) the number of root canals per tooth, (2) the distance between the mesiobuccal and distobuccal root canal orifice (DM), (3) the distance between the palatal and distobuccal root canal orifice (DP), (4) the angle formed by the mesiobuccal, distobuccal and palatal root canal orifices (∠PDM). DM, DP and ∠PDM of the teeth with three or four root canals were analyzed and evaluated. Results: In total, 763 (93.51%) of 816 maxillary second molars had three or four root canals. The distance between the mesiobuccal and distobuccal orifice was 0.7 to 4.8 mm. 621 (81.39%) of 763 teeth were distributed within 1.5-3.0 mm. The distance between the palatal and distobuccal orifice ranged from 0.8 mm to 6.7 mm; 585 (76.67%) and were distributed within 3.0-5.0 mm. The angle (∠PDM) ranged from 69. 4º to 174.7º in 708 samples (92.80%), the angle ranged from 90º to 140º. Conclusions: The position of the distobuccal root canal orifice of the maxillary second molars with 3 or 4 root canals in a Chinese population was complex and variable. Clinicians should have a thorough knowledge of the anatomy of the maxillary second molars.

Clinical effects of pendulum and straight wire technology in patients with fully erupted maxillary second molar / 中华医学美学美容杂志

ObjectiveTo investigate the clinical effect of pendulum and straight wire technology in patients with fully erupted second molar.MethodsPatients with Angle class Ⅱ malocclusion were chosen.Control group included patients without erupted second molar.Experimental group included patients with completely erupted second molar.Pendulums were used in two groups to distalize maxillary molars.Then straight wire orthodontic treatment had been performed until treatment was over.Cephalograms of each stage were analyzed.ResultsIn the experimental group,mesiobuccal cusp of first molar was distalized for 4.62 mm,geometric center was distalized for 3.75 mm,about 81 percent of the movement of mesiobuccal cusp.In control group,mesiobuccal cusp of first molar was dis talized for 5.78 mm,geometric center was distalized for 3.20 mm,about 55 percent of the movement of mesiobuccal cusp.It turned out first molar was distalized in both groups,but more rotation took place in control group than that in the experimental group.ConclusionsPendulum can distalize maxillary first and second molars in patients with completely erupted second molar.The pendulum and straight wire technology can treat these patients successfully.

Pretreatment characteristics of adolescents with Class II malocclusion treated by maxillary second molar extraction / 대한치과교정학회지

The purpose of this retrospective study was to estimate the pretreatment characteristics of growing patients with Class II malocclusion, who had been treated with maxillary second molar extractions. The sample comprised of 51 subjects; 18 subjects were classified into the molar extraction group, and 33 subjects were treated without extraction and classified into the nonextraction group. Pretreatment lateral cephalograms were calculated and analyzed by independent t-test and stepwise discriminant analysis. In measurements for skeletal pattern, no anteroposterior measurements and proportions of various vertical dimensions were significantly different, and only some measurements such as AB-MP (degree), Na-Me (mm), AVD (mm) were significantly different between the two treatment groups (p < 0.05). In measurements for dentoalveolar pattern, some measurements, which were related to the position and angulation of the upper and lower permanent first molars, and the angulation of the upper third molars, were significantly different between the two treatment groups. In particular, the maxillary second molar extraction group exhibited more mesial angulation of maxillary first molar to the occlusal plane.

Three dimensional finite element analysis of the phenomenon during distal en masse movement of the maxillary dentition / 대한치과교정학회지

This study was designed to analysis the displacement and stress distribution of individual tooth by orthodontic force during distal en masse movement of the maxillary dentition. In this study, three dimensional finite element analysis was used. Author made the finite element model of maxillary teeth, periodontal ligament, alveolar bone and bracket with anatomic and physiologic characteristics on computer. Author analysed and evaluated the displacement and stress distribution of individual tooth when extraoral force, Class II intermaxillary elastics, ideal arch wire, MEAW and tip back bend were used for distal en masse movement of the maxillary dentition. These analyses were also applied in the case of the maxillary second molar were not extracted. Author compared the results of the cases which maxillary second molar were extracted or not. The results were expressed quantitatively and visually. Author obtained following results, 1. When anterior headgear was applied, the posterior translation, posterior tipping, and vertical displacement of teeth were produced more in the anterior segment of the dentition. 2. When Class II intermaxillary elastics were applied in the ideal arch wire, the teeth disp acement were usually produced in the anterior segment. But when tip back bend were added in the ideal arch, the orthodontic force produced by elastics were transmitted to the posterior segment. As increasing the tip back bend, posterior translation and lingual tipping of anterior teeth were decreased, posterior translation and tipping displacement of posterior teeth were increased, and extrusion of anterior teeth by Class II elastics were decreased. 3. When MEAW and Class II elastics were applied, the teeth movement were similar with the case of ideal arch wire and Class II elastics, but more small and uniform teeth displacement were produced. Compared with the ideal arch wire, posterior tipping of the posterior segment were more produced than lingual tipping displacement of the anterior segment. 4. When the maxillary second molar without orthodontic appliance existed, the displacement of maxillary first molar were decreased.