Evaluation of two shaping systems and two sonic irrigation devices in removing root canal filling material from distal roots of mandibular molars assessed by micro CT.

AIM: To compare two preparation systems and two sonic irrigation devices during the removal of root filling material from oval distal canals of extracted mandibular molars. METHODOLOGY: The distal canals in 40 extracted mandibular molars were shaped using the ProTaper Next system (Dentslpy Sirona, Ballaigues, Switzerland), filled with Gutta Percha X2 (Dentsply Sirona), along with AH Plus sealer (Dentsply De Trey, Konstanz, Germany) and randomly divided into two groups (n = 20) according to volume of initial filling, preparation diameter and working length. One group was retreated using the Reciproc system (VDW, Munich, Germany), and the other using the 2Shape system (Micro-Mega, Besançon, France). A micro-CT scan was taken after the initial root filling and after retreatment to evaluate the volume of filling material remnants. The teeth were divided into four groups to test the supplementary effect of two sonic irrigation devices on removing filling material: Eddy (VDW) and MM1500 (Micro-Mega). In the first and second groups, 2Shape was followed subsequently by MM1500 and Eddy; in the third and fourth groups, Reciproc was followed by MM1500 and Eddy. A third micro-CT was taken to compare the remaining root filling material in all groups. Wilcoxon's signed rank tests, Mann-Whitney and Kruskal-Wallis tests were used for statistical analysis. RESULTS: No significant difference was found for the volume of filling material removed between the Reciproc and 2Shape in the entire canal (P = 0.355). The volume dropped significantly from its initial value after removing the bulk of the root filling by 95.8% (from 4.71 to 0.22 mm3 ) with the 2Shape (P < 0.001) and by 94.0% (from 5.05 to 0.33 mm3 ) with the Reciproc (P < 0.001). Sonic activation significantly decreased the residual volume of filling material remnants by 3.21% (P = 0.013) in the first group, 1.38% (P = 0.012) in the second group, 1.83% (P = 0.008) in the third group and 1.83% (P = 0.012) in the fourth group. At the end, the percentage of residual material was not significantly different among the groups in the entire canal (P = 0.163). CONCLUSION: In the distal oval canals of extracted mandibular molar teeth, there was no significant difference between the 2Shape and Reciproc systems in removing gutta-percha/sealer. Sonic activation with MM1500 and Eddy significantly improved filling material removal.

Comparative study of two different computer-controlled local anesthesia injection systems in children: a randomized clinical trial.

PURPOSE: To compare pain perception associated with two computer-controlled local anesthesia devices, the WAND™ STA (Milestone Scientific Inc., Livingston, NJ, USA) and the Calaject (Rønvig dental MFG, Daugaard, Denmark) in young children. METHODS: A split-mouth randomized clinical trial comprising 30 patients, aged 6-12 years, received randomly, in two separate sessions, a local anesthesia injection in the maxillary using either the wand STA or the Calaject. Pain perception was evaluated using the patient's heart rate, an 11-point numerical scale (NRS), and the Sound, Eye, and Motor (SEM) body movements. Statistical difference was set at p = 0.05. Repeated measures analysis of variance were conducted to compare the mean pulse for Calaject and STA at different times. It was followed by univariate analysis and Bonferroni multiple comparisons tests. Wilcoxon tests were performed to compare NRS, SEM, and injection duration between Calaject and STA. RESULTS: There was no significant statistical difference between Calaject and STA in pulse rate before injection (p = 0.720), during injection (p = 0.767), and after injection (p = 0.757). The mean NRS score was significantly greater with STA in comparison with Calaject (p = 0.017). The mean SEM score was also significantly greater with STA in comparison with Calaject (p = 0.002). However, the mean duration was significantly longer with Calaject (p = 0.001). CONCLUSIONS: Calaject was more effective than STA in reducing pain perception associated with periapical injection in young children.

Metallic syringe versus electronically assisted injection system: a comparative clinical study in children.

AIM: Local anaesthesia injection necessary for pain control in paediatric dentistry may itself be painful sometimes, partly because of the pressure felt during injection; electronically assisted injection systems were developed to address this problem. MATERIALS AND METHODS: Study design: The present study is a clinical study in children that compared two types of devices for paediatric buccal infiltration anaesthesia: the aspirating syringe and an electronically assisted injection system, the Wand STA. A split mouth, randomised controlled clinical trial was conducted on 30 healthy six to eight-year-old patients (6.64 ± 0.803 years) requiring pulpotomies on two symmetrical primary maxillary molars. Each patient received the following types of anaesthesia, in separate, consecutive, randomly ordered sessions: conventional buccal infiltration by metallic aspirating syringe and buccal infiltration by computer-controlled local anaesthetic device (Single Tooth Anesthesia). Parameters assessed were: pain experienced during injection, patient's heart rate and behaviour, anaesthesia quantity required and onset time. RESULTS: No statistical differences were observed between the two techniques (p? 0.05) for all assessed parameters. CONCLUSIONS: Results suggest that computer-assisted anaesthesia may represent an alternative to conventional syringes for local buccal anaesthesia in paediatric dental treatment; comparison to other types of dental infiltration anaesthesia needs further investigation.

Three-dimensional modeling and measurements of root canal anatomy in second primary mandibular molars: a case series micro CT study.

PURPOSE: This study aimed at establishing a comprehensive specification of the root canal anatomy of second primary mandibular molars using micro computed tomography (CT). METHODS: 10 s primary molars from Caucasian young patients were selected for this purpose. Micro CT imaging with a high resolution of 20 microns was performed to observe the roots and canals according to specific criteria. The Vertucci canal configuration, the presence of lateral canals and their location, the presence of an isthmus and its location, were first observed. Then, the length of the canals, their diameter in the mesio-distal and vestibulo-lingual direction, the dentinal thickness and the direction of the minimal dentinal thickness were measured. RESULTS: The mean working length was not significantly different between the canals (p = 0.710). The bucco-lingual diameter was significantly higher when the tooth had a single distal canal at the coronal (p < 0.001), middle (p < 0.001) and apical (p = 0.012) levels. The root dentin thickness on the distal wall of the mesial root and the mesial wall of the distal roots were reduced, respectively, from the coronal to the apical thirds. CONCLUSIONS: The results obtained in this case series report clearly show a complex, sometimes unpredictable, anatomy with dangerous areas where dentin is extremely thin. The plethoric presence of anastomoses, large bands of isthmus, lateral canals at all levels induces the need for the development of instruments specific to pulpectomies on primary teeth.