ENDO, 02/2012

The complexity of endo-perio lesions reflects the relevance of a close developmental relationship between the pulp and periodontal tissues. A review of the literature was undertaken to discuss the complex and dynamic nature of normal anatomical and pathological pulp and periodontal intercommunication pathways. This interrelationship was then correlated with the criteria followed in previous classifications for endo-perio lesions. Based on this analysis, the most reliable criteria and the missing patterns of endo-perio lesions were identified, and then described in a proposed new classification. Keywords: classification, endo-perio lesions, periodontal, pulp

Aim: To gain an overview of the basic concept of tissue engineering, which helps in understanding its potential application and scope in the field of clinical endodontic practice. Summary: The accepted use of regenerative therapy in the field of endodontics can be designed to restore and replace lost dentine, pulp, cementum and periodontal tissues. The key elements of tissue engineering are the stem cells or units, the signals or growth factors/morphogens (GFs), and a carrier or scaffold of extracellular matrix. The dental pulp has been identified as a source of mesenchymal stem cells, which by definition are adult multipotent stem cells that are capable of differentiating into mesenchymal and non-mesenchymal tissues, such as fat, bone, cartilage and neural cells. The pulp from extracted third molars, teeth extracted for orthodontic or periodontal reasons or supernumerary teeth offer a valuable source of stem cells for research. Autologous dental pulp stem cells may be frequently used for pulp regeneration. Induced pluripotent stem cells, which are artificially derived through stem cell gene transfer into an adult stem cell, may have the potential to be utilised as an alternative source for autologous pulp tissue regeneration. Keywords: adult stem cells, dental pulp, regeneration, root canal therapy, tissue engineering

Aim: The purpose of this study was to compare the incidence of deformation and instrument separation of rotary nickel-titanium instruments used clinically by the same operator according to a predefined schedule. Methodology: A total of 110 ProFile instruments (Dentsply Maillefer, Ballaigues, Switzerland), discarded from an endodontic clinic, were analysed. Results: The incidences of instrument separation were 4.5% and for unwinding of the instruments 12.7% respectively. Flexural fatigue was implicated in the majority of separations. Conclusions: The results of this study indicated that ProFile instruments tended to exhibit unwinding of flutes more frequently than deformation and separation. Keywords: nickel-titanium (NiTi), ProFile, rotary root canal instruments, surface defects

Aim: A new radiographic technique, multislice computer tomography, was used to compare apical transportation, centreing ability, percentage of straightening and change in canal volume in maxillary mesiobuccal root canals prepared with Hero Shaper (Micro Méga, Besançon, France) and Revo-S NiTi (Micro Méga) rotary systems. Methods: Thirty mesiobuccal roots were selected and assigned into two groups (n = 15). Group I was instrumented by the Revo-S system and Group II was instrumented by the Hero Shaper system. Three-dimensional computed tomography images of the preinstrumentation and postinstrumentation stages were digitally analysed, recording the amount of apical transportation, centreing ratio, percentage of straightening and change in canal volume. A Mann Whitney U-test was adopted to compare the obtained data. Results: No statistically significant difference was recorded between the two studied systems regarding transportation, centreing ratio and canal volume (P > 0.05). Revo-S maintained the original canal curvature better than Hero Shaper (P < 0.05). Conclusions: Hero Shaper and Revo-S should be considered as efficient systems, which respect the original root canal anatomy with no resulting aberrations or failures. Keywords: centre ratio, computed tomography, Hero Shaper, Revo-S, transportation

Aim: The purpose of this study was to compare the canal centreing ability of three nickel-titanium (NiTi) rotary systems (Mtwo, Twisted Files and Revo-S). Materials and methods: Sixty mesial root canals of mandibular first molars with curvatures ranging from 25 to 35 degrees were randomly divided into three groups. Root canals were instrumented using Mtwo (VDW, Munich, Germany), Twisted Files (TF) (SybronEndo, Orange, CA, USA) or Revo-S (RS) (Micro-Méga, Besançon, France) rotary NiTi instruments. The roots were sectioned horizontally at 3 mm, 6 mm and 9 mm from the root apex. Teeth were reassembled and the canals instrumented according to the manufacturers' guidelines up to master apical file size 30. The cross sections of the root canals were digitally scanned before and after preparation, and image analysis software was used to assess the centreing ability. The three groups were statistically compared using analysis of variance (ANOVA) and the Tukey HSD test (P < 0.05). Results: TF produced the lowest total mean centreing ratio (0.042 ± 0.005) at all canal regions (P < 0.05). RS produced the highest total mean centreing ratio (0.598 ± 0.12) (P < 0.05) followed by Mtwo files (0.194 ± 0.02). Conclusions: Twisted Files provided the least canal transportation, remained centred in the canal and preserved the original canal cross section to a greater degree than Revo-S and Mtwo instruments. Keywords: canal transportation, centreing ability, curved root canals, M-wire

This case report presents successful immediate mandibular third molar autotransplantation to replace a non-restorable mandibular first molar. In this case, after the extraction of the non-restorable tooth, the donor molar with incomplete root formation was autotransplanted into the recipient site after atraumatic extraction. A long term continuous follow-up of 2 years revealed that the tooth was fixed in its socket without residual inflammation; masticatory function was satisfactory and without discomfort; the tooth was not mobile; no pathological condition was apparent radiographically; the lamina dura appeared normal and the tooth showed radiographic evidence of root growth. Pulpal regeneration and the depth of the pocket, gingival contour, and gingival colour were all normal. The purpose of this case report is to demonstrate the clinical application of autotransplantation as a future option for permanent restoration without implants, orthodontic space closure or partial denture. Keywords: autotransplantation, complete root formation, pulpal regeneration

Aim: Root canal treatment of a taurodont tooth is challenging because of the wide variations in the anatomy of the pulp chamber and root canal configurations. The nonsurgical root canal treatment of an unusual case of taurodontism in a maxillary central incisor is reported in this study. Methods: Clinical and radiographic examinations of a right maxillary central incisor revealed the presence of a sinus tract, a short root with apical displacement of the floor of the pulp chamber and two root canals. A large periradicular lesion was observed, and the diagnosis of asymptomatic suppurative apical periodontitis was made, and root canal treatment was carried out. The root canals were accessed, chemomechanically prepared and filled with a calcium hydroxide dressing. The dressing was replaced over a 6-month period. A significant reduction in periradicular radiolucency was observed, and obturation of the root canal system was undertaken using a warm compaction technique with gutta-percha and an epoxy resin-based sealer. Results: The tooth was asymptomatic and functional, and periapical repair was observed radiographically after an 18-month follow-up. Conclusion: Although taurodontism is an anomaly predominantly seen in multirooted teeth, this case report describes how a non-surgical root canal treatment of an unusual taurodont maxillary central incisor was performed. Keywords: morphologic change, nonsurgical endodontic treatment, pulp chamber, taurodontism

Aim: The purpose of this study was to emphasise the importance of familiarisation with the internal anatomy of the mesial root of human permanent mandibular molars. Materials and methods: A literature review was conducted and four clinical cases of mandibular molars exhibiting an additional middle mesial canal are presented. Non-surgical treatment and retreatment procedures are described. Results: The middle mesial canals in all cases demonstrated a merging configuration with either the mesiobuccal or the mesiolingual canal. Acknowledgement of this configuration bears significant clinical implications. Enhanced magnification and illumination were indispensable for the detection and negotiation of the intermediate canal. Conclusions: The middle mesial canal constitutes an anatomic component that needs to be acknowledged during endodontic treatment of the mandibular molars. Awareness of its occurrence along with visual augmentation may aid a higher detection rate. Keywords: mandibular molars, middle mesial canal, root canal anatomy