ENDO, 02/2011

bacOne of the recent trends in endodontics is the development of adhesive obturation materials to improve the seal quality in root canal fillings and to strengthen roots. This review discusses the materials utilising dentine adhesive technology in endodontics in an attempt to provide a monoblock for rehabilitation of the root canal space and to achieve mechanically homogenous units with the root dentine. This article is the second part of a two-part series on adhesives in endodontics. Part I covered the limitations and effects of different materials and can be found in ENDO (Lond Engl) 2009;3:185-204. Keywords: adhesion, adhesives, monoblock, obturation, resin-based sealer

Aim: To describe a clinical case, a rare complication, in which two mandibular incisors became discoloured following bone harvesting for pre-implant augmentation. Summary: A 57-year-old woman was referred by her general dental practitioner regarding discolouration of her mandibular right central and lateral incisors. A segmental osteotomy was performed in the vicinity of these incisors about 4 weeks previously to harvest bone, which was grafted to provide support for the placement of an implant to replace the missing maxillary right canine. Although both incisors were symptom-free, they were non-responsive to sensitivity tests. Non-surgical root canal treatment was carried out to both of these non-vital teeth, followed by intracoronal bleaching to improve their colour. Key learning points: 1. Pre-implant bone grafting procedures may risk disrupting the blood supply of teeth situated close to the harvesting site. 2. If the blood supply of teeth is compromised, this may lead to loss of vitality and tooth discolouration. 3. The length, morphology and position of the roots of teeth should be carefully evaluated using periapical radiographs, and if necessary, tomographic imaging techniques to avoid this iatrogenic sequelae. 4. The consequences of loss of vitality and tooth discolouration are managed conservatively by root canal treatment and internal bleaching. Keywords: bone augmentation, bone grafts, root canal treatment, surgical complications, tooth bleaching, tooth discolouration

The aim of this paper is to report the diagnosis and successful clinical treatment of a maxillary central incisor with internal tunnelling replacement resorption. A case is presented in which internal replacement resorption in a maxillary central incisor developed after the patient had a bicycle accident 15 years previously. A preoperative radiograph showed two distinct radiolucent lesions in the apical middle of the root canal; one was irregularly oval shaped and the other, attached to the former, was horseshoe shaped. A computed tomography scan showed no evidence of periodontal ligament communication. Root canal treatment was completed in one visit and a 12-month follow-up showed no signs of periapical pathology. Keywords: computed tomography, internal replacement resorption, root canal, surgical operating microscope, tunnelling resorption

Aim: The literature shows a wide variation in the number of root canals and canal morphology of maxillary premolars. The aim of the present study was to evaluate the root canal anatomy of maxillary premolars in an Indian subpopulation with the aid of spiral computed tomography (CT). Materials and methods: Computed tomographic scans of 67 patients were taken and analysed from a radiology database. A total of 119 maxillary first premolars and 121 maxillary second premolars were studied. Axial images of maxillary premolars, obtained from CT scans, were evaluated at all levels. The criteria evaluated were: number of root canals, root canal morphology classified by Weine (I-IV) and canal morphology classified by Vertucci (I-VIII). Results: A total of 2.5% of maxillary first premolars had one canal (Weine type I, Vertucci type I), whereas the rest had two canals (Weine type II-III, Vertucci type II-IV). In maxillary second premolars, 55.3% of teeth had one canal (Weine type I, Vertucci type I). One case demonstrated a Vertucci type VII canal configuration. Conclusions: Maxillary premolars of an Indian subpopulation demonstrated various canal morphologies and shapes, with predominantly two canals in the maxillary first premolar. A CT scan can be a useful tool in the accurate determination of root canal configuration. Keywords: computed tomography, maxillary premolars, root canal anatomy, Vertucci's classification

This case report presents the root canal treatment of bilateral mandibular first molars exhibiting three roots (one mesial and two distal) and five root canals (two in the mesial and three in the distal root). This unusual anatomic variation was diagnosed with an operating microscope and confirmed with the help of spiral computerised tomography (SCT). SCT was used as a non-invasive diagnostic tool to visualise the anatomy of the roots and the root canals precisely. Anatomical variations can occur in any tooth. Therefore careful examination of radiographs and internal anatomy of teeth is essential for successful root canal treatment. Keywords: dental operating microscope, mandibular first molar, spiral computerised tomography, three distal root canals

The aim of this study was to determine the area filled by gutta-percha and sealer and occupied by voids in the different thirds of root canals shaped with ProTaper and sealed using two different single-cone techniques. The root canals of 20 mandibular premolars were prepared with Gates Glidden drills #1, 2 and 3, and shaped using ProTaper instruments. The teeth were randomly divided into two groups; in group G1 the canals were obturated with a single ProTaper F3 cone, and in group G2 with a single 0.06 taper size 40 gutta-percha cone, using N-Rickert sealer in both groups. The roots were sectioned transversally into thirds, and the quantities of gutta-percha and sealer were assessed by ANOVA and post-hoc Tukey test. The voids were analysed by the Kruskal-Wallis test, with a comparison of ranked means by the Student-Newman-Keuls test. In all cases, the level of significance was set at 5%. The amounts of gutta-percha and sealer showed significant differences between the techniques in the different root thirds (P < 0.0001). Group G1 showed less gutta-percha when compared to group G2, and there was a greater quantity of sealer in the cervical third with both techniques. In relation to the percentage of voids, the middle third of group G1 differed from the middle and apical thirds of group G2 (P < 0.05). The use of 0.06 taper gutta-percha cones in root canals shaped with ProTaper resulted in more satisfactory results when compared to the original ProTaper single-cone technique. Keywords: gutta-percha, ProTaper, root canal obturation, voids

The aim of this investigation was to compare the ability to fill simulated lateral canals in primary and re-treatment cases using a single gutta-percha point technique or the Thermafil system. Forty single-rooted mandibular premolars were randomly divided into two equal groups (n = 20). In group A, the root canals were instrumented with ProFiles to a size 40/.04. A #15 engine reamer was used to create three simulated lateral canals on in each root third. The canals were then instrumented to a ProFile 40/.06. Group A was then divided into two subgroups of 10 each. The A1 specimens were filled with a single 40/.06 gutta-percha cone and A2 specimens filled with a #40 Thermafil obturator. The remaining 20 teeth (group B) were instrumented to a K-file #35 and filled using cold lateral compaction of gutta-percha and Grossman's sealer. Also, three simulated lateral canals were prepared in each third. The root canal fillings were then removed and digital radiographs were taken in a buccolingual direction. The group B samples were divided into two subgroups (n = 10) and were filled in the same fashion as groups A1 and A2 respectively. TopSeal was used as sealer and digital radiographs were taken after obturation in all subgroups. The results showed that teeth in group A showed a higher number of filled lateral canals when compared to group B. A statistically significant difference was observed between group A and B (P < 0.01), yet no differences were found between the subgroups A1 and A2, and B1 and B2 (P > 0.05). According to the results, it was demonstrated that lateral canals can be filled more frequently during primary treatment than during re-treatment. Keywords: lateral canals, obturation, re-treatment

Introduction: The aim of this study was to determine the effect of thermal treatment on the flexural resistance of mechanically pre-fatigued rotary nickel-titanium (NiTi) endodontic instruments. Methods: New and mechanically pre-fatigued rotary NiTi instruments were subjected to thermal treatments at 350˚C, 400˚C and 450˚C for 30 minutes, and then were rotated in a fatigue-testing device until fracture. The time to fracture was recorded and multiplied by the number of rotations per minute to obtain the number of cycles to failure (NCF) for each group. One-way analysis of variance (ANOVA) followed by Tukey-Kramer multiple-comparison post hoc test was used for the comparison between the different tested groups. Fractographic examination by scanning electron microscopy was also performed to study the morphological characteristics of the fractured instruments. Results: Statistical analysis showed that the thermal treatment at or below 400˚C of the new files did not improve the resistance to the flexural fatigue. Also, the flexural fatigue resistance of mechanically pre-fatigued files was significantly lower than that of new files. However, with thermal treatment significant improvement in the resistance to flexural fatigue was achieved, especially at 450˚C (P < 0.05). Conclusion: Thermal treatment seems to be of significance in improving the cyclic fatigue resistance or life span of fatigued or used NiTi files. Keywords: flexural resistance, nickel titanium, thermal treatment