A non-carious cervical lesion (NCCL) is the loss of hard dental tissue on the neck of the tooth, most frequently located on the vestibular plane. Causal agents are diverse and mutually interrelated.In the present study all vestibular NCCL were observed and recorded by the tooth wear index (TWI). The aim of the study was to determine the prevalence and severity of NCCL. For this purpose, 18 555 teeth from the permanent dentition were examined in a population from the city of Rijeka, Croatia. Subjects were divided into six age groups. The teeth with most NCCL were the lower premolars, which also had the largest percentage of higher index levels, indicating the greater severity of the lesions. The most frequent index level was 1, and the prevalence and severity of the lesions increased with age.

The PAD and EndoActivator system were more successful in reducing the root canal infection than the diode laser and NaOCl syringe irrigation alone.

The aim of this study was to evaluate the cytotoxicity of the root canal sealers RoekoSeal Automix (RSA) and AH Plus in vitro on human cervical carcinoma (HeLa) cells and mouse skin fibroblasts (L929). The sealers were covered with a 3 x 10(4) cell suspension 1 h, 24 h, 48 h, 7 days and 1 month after mixing. Four samples and respective controls without sealer were prepared. After 5 days of incubation, the number of cells was determined using an electronic counter; the number of viable cells was determined under light microscopy following the addition of nigrosin dye. The experiment was repeated twice for each sealer and each period. AH Plus was significantly more cytotoxic after 1 h, 24 h, and 48 h, compared to the 7 day and 1 month setting period on both cell lines. RoekoSeal had no cytotoxic effect on either cell line at any setting time.

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The aim of this study was to develop a three-dimensional (3D) finite element model (FEM) of the first maxillary premolar in order to compare the stress profiles in the buccal and palatal cervical regions. The 3D geometry of the tooth was reconstructed, the solid model was transferred into a finite element program where a 3D mesh was created, and the stress distribution analysis was performed. Two typical cases have been considered: the tooth under normal occlusion (case I) and the tooth under malocclusion (case II). In case I, larger compressive stresses were found in the cervical enamel and dentine. Tensile stresses were found in the fissure system, adjacent area, and at the vestibular surface of the buccal cusp. The peak values for the principal stress ranged from -259 to +2.25 MPa in the cervical areas. In the case II, larger compressive stresses were found in the palato-cervical enamel and dentine. Tensile stresses were found inside the enamel in the fissure system, adjacent area, at the vestibular surface of the buccal cusp, and in the bucco-cervical enamel. The peak values for the principal stress ranged from -501.947 MPa in palatal region to +82.4 MPa in the buccal region This study implies a role of occlusal forces in development of non-carious lesions. In the case of malocclusion, tensile stresses generated on the cervical areas were higher compared with the stresses generated in the case of normal occlusion and it is probably capable of producing non-carious cervical lesion.

The aim of the study was to evaluate the efficacy of photon-initiated photoacoustic streaming (PIPS) in the removal of filling remnants from root canals after rotary phase of retreatment and to examine the difference in the amount of residual material considering the type of sealer. Thirty-six extracted single-rooted human teeth were instrumented and randomly divided into three groups according to the filling material used: group 1: EndoSequence BC Sealer (Brassler, USA), group 2: MTA Fillapex (Angelus Solucoes Odontologicas, Londrina, Brasil), and group 3: AH Plus sealer (Dentsply DeTrey, Konstanz, Germany). Cold lateral condensation technique was used. After 2 weeks, the root canals were retreated with a rotary phase retreatment system (ProTaper Universal Retreatment, Maillefer, Ballaigues, Switzerland), followed by Er:YAG laser-activated irrigation (photon-initiated photoacoustic streaming, PIPS). The specimens were scanned in a micro-computed tomographic (micro-CT) device after root canal filling, after the rotary retreatment, and after the PIPS. There was significant reduction in the amount of filling material after the rotary phase of retreatment in all groups (p < 0.05), the highest in the MTA Fillapex group (p < 0.001) and no difference between the EndoSequence BC and the AH Plus (p = 0.608). There was significant reduction of the filling remnants after the PIPS in all groups (p < 0.05). The MTA Fillapex was the most easily removed during rotary phase of the retreatment, and there were no differences in the amount of the remaining filling material between EndoSequence BC and the AH Plus groups after rotary phase of the retreatment. The PIPS improved the removal of filling remnants in all groups.

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The permeability, temperature and morphologic changes of the wall of the root canal induced by Nd:YAG, CO2 and argon lasers were studied. The changes were evaluated according to the presence or absence of a smear layer. Root canals of 140 human single-rooted teeth were enlarged using a step-back technique. Permeability was evaluated by the extent of methylene blue dye penetration into the tubules. Temperature changes were measured using a thermovision system, and morphological changes were evaluated by scanning electron microscopy. Laser energy was delivered into the canal by means of a flexible optical fibre or metal tip. There were statistically significant differences in permeability between lased groups with and without a smear layer in the cervical third of the root canal following lasing. In the middle third of the root canal, all three laser types induced permeability increases in groups with a smear layer. In the apical third, statistically significantly decreases in permeability were observed among CO2 laser and Nd:YAG compared with control group (P < 0.01). Rises in temperature ranged from a minimum of +10.1 degrees C (CO2 laser) to a maximum of +54.8 degrees C (argon laser). All three laser devices appeared capable of producing a glazed-like surface and craters.