Article: Clinical evaluation of restorations with self-etch adhesive and nanofilled composite in class I and class II cavities.Neshka A Manchorova, Stoyan B Vladimirov, Zoya K Donencheva, Ivan S Drashkovich, Stanislav K Manolov, Veselina I Todorova[show abstract] [hide abstract]
ABSTRACT: In the era of adhesive restorative dentistry the principles of conventional cavity preparation have acquired a new meaning. The emphasis is shifted from "widening for preventive purposes" and preparation of macro-mechanical retention to "consciously limited" preparation. The clinical and biological durability of restorations depends on the adhesive bond and the quality of the composite material. The aim of the study was to conduct a clinical evaluation of restorations with a self-etch single-step adhesive and nanofilled composite in class I and class II cavities over a period of 15 months. The clinical trial involved 34 patient (volunteers) who received 76 posterior restorations of medium and deep cavities with the self-etch adhesive Adper Prompt L-Pop and nanofilled composite Filtek Supreme (3MESPE Dental products USA). All restorations were evaluated by the modified Ryge and Cvar criteria at 6- and 15-month intervals. Loss of restorations with a self-etch single-step adhesive and nanofilled composite at 6 months and 15 months was 0% and 6.7%, respectively. The evaluation of discolouration in the restorations at 6 months revealed no significant changes (P > 0.05, u = 1.72). There was certain deterioration in the colour at 15 months (P < 0.05, u = 2.96). Statistically significant changes in the marginal discolouration were observed at 6 months (P < 0.05, u = 2.79) in comparison with the initial scores. During the 15-month follow-up the discolouration on the margins of the restorations was statistically nonsignificant compared to the 6-month follow-up (P > 0.05, u = 0.36). There were no C (Charlie) scores recorded during the 15-month follow-up study within the continuing observation. The restorations with nanofilled composite and self-etch single-step adhesive fulfill the requirements for clinical use in posterior restorations.Folia medica 01/2008; 50(1):46-52.
Article: Factors for post-operative sensitivity in dental caries treatment according to practicing dentists--application of network analysis.[show abstract] [hide abstract]
ABSTRACT: The postoperative tooth sensitivity is a dental caries post-treatment complication of unknown origin. The variety of clinical symptoms of this condition, the contributing factors and their interactions may be presented by means of network analysis. The aim of the present study was to apply network analysis to present the relationships between factors contributing to post-operative sensitivity according to practicing dentists. We carried out an anonymous questionnaire survey of 213 dentists to assess their experience with diagnosed post-operative sensitivity. The duration and kind of the condition was studied to find its correlation with the type of restorative material, the location of carious defect, and the depth of carious defect. The respondents gave their opinions about the probable causes of post-operative sensitivity. Multiple answers to one question were allowed. Data was processed with the help of SPSS and UciNet. 806 ties between factors for post-operative sensitivity were investigated. Their absolute size (C) ranged from -16 to +175. The most significant relationships, defined at C > or = 0.3, comprised 20% of all ties. The following relationships between factors associated with post-operative sensitivity were found: cold-induced pain of up to 1 week duration after treatment of caries profunda acuta and placement of an amalgam restoration; pressure-induced pain of up to 3 weeks duration after treatment of caries profunda chronica, class II cavities and placement of a composite resin restoration. The visualized structures of interrelated factors represented only the clinical experience of the questioned dentists. Their confirmation in clinical practice is a matter of future investigations.Folia medica 01/2006; 48(3-4):68-73.
Article: A study of post-operative sensitivity in class I and class II restorations with self-etching adhesive and nanofilled composite.Neshka A Manchorova, Stoyan B Vladimirov, Zoya K Donencheva, Ivan S Drashkovich, Plamen Zh Kozhuharov, Stanislav K Manolov, Rangel G Todorov[show abstract] [hide abstract]
ABSTRACT: The aim of the study was to determine the type, intensity and duration of post operative sensitivity (POS) in class I and II cavity restorations with self-etching adhesive and nanofilled composite. The clinical study included 34 patients, who received a total of 76 restorations by undergraduate dental students. The restorations were made in medium and deep cavities. Self-etching adhesive Adper Promp L-Pop and nanocomposite Filtek Supreme (3MESPE Dental products USA) were placed. The type, the magnitude and the duration of postoperative sensitivity were examined on days 1, 3, 5, 7, 14 and 30. Intensity of sensitivity perceptions were recorded on a visual analogue scale using the method of self-observation. Parametric and non-parametric analyses were employed at a significance level of P < 0.05. Pressure-dependent POS was present in most of the cases (15.78% +/- 4.209), followed by discomfort (9.21% +/- 3.340) and pressure- and cold-induced pain (1.33% +/- 1.147). A statistically significant difference was found between days 1 and 3, and between days 5 and 30, as well as between days 7 and 30 (Wilcoxon Signed Ranks Test, P < 0.05). Rapidly disappearing POS (within 1 week) had the highest percentage: 75% +/- 9.934. Following restoration of class I and II cavities with self-etching adhesive and nanofilled composite POS was established in 26.3% of the cases.Folia medica 01/2006; 48(2):63-9.
Article: Three-dimensional analysis of cavity wall deformation after composite restoration of masticatory teeth.Neshka A Manchorova-Veleva[show abstract] [hide abstract]
ABSTRACT: The aim of the present work was to study the size of cavity wall deformation in eight class I and II defects after composite restoration. 1. Creating a geometric model - data on the size of the left maxillary second premolar were obtained from a routine craniofacial scanning of a 20-year-old patient with a 2,5 Dental CT scanner (General Electric), with high resolution and 0.625mm-thin slices. The contour of each of the 33 cross-sections of tooth 25 was delineated using graphics software (CorelDraw 7.0) and transferred to a specialized product for engineering design (SolidWorks Office Premium 2010, SolidWorks Corp. USA). The pulp cavity and periodontal ligament were created in the same manner and were integrated in the premolar body; 2. Generation of a finite element method - the geometric model was exported to specialized software for analysis by the finite element method - COSMOSWorks 2010, which automatically builds a 3D finite elements mesh. Based on the generated model, eight additional models of class I and II cavities with different geometries, adhesive layer and nanofilled composite restorations were constructed. The polymerization shrinkage was modelled by thermal deformation, with a negative temperature difference (cooling), corresponding to the actual volume shrinkage of the composite materials by 2.1%. In models A and B, the maximum cavity wall displacement was small - 0.014 mm and 0.015 mm, respectively. In models Al, B1, C1 and C, the displacement was at the expense of large deformation of the dental tissues. The maximum cavity wall displacements were 0.020 mm, 0.026 mm, 0.020 mm, 0.035 mm, respectively. The least cavity wall displacement was in models A2 and B2 with 0.008 mm and 0.017 mm, respectively. CONCLUSIONs: The least displacement resulting from cavity wall deformation is found in patient-friendly class I and II preparations. Preservation of the dental tissues reduces the risk of mechanical pressure on the dentinal lymph and the likelihood of post-operative sensitivity.Folia medica 53(4):53-9.
Article: Three-dimensional biomechanical study of functional stresses in composite restorations of masticatory teeth.Neshka A Manchorova-Veleva[show abstract] [hide abstract]
ABSTRACT: The aim of the present work was to study and evaluate the intensity of stresses in the adhesive bond in composite restorations of masticatory teeth after light-curing, under temperature changes and masticatory loads. Data for the 3D model generation of a maxillary premolar were obtained during a routine CT head scan. Thirty-three cross-sections of tooth 25 were selected and used to create a 3D geometric model enmeshed using the finite element method (FEM) (made up of 106556 elements and 608724 nodes). The pulp cavity and the periodontal ligament were constructed in the same way and integrated into the premolar model. Eight cavity configurations with converging walls were designed, resistant to masticatory forces (enamel/dentin = 1/1). A comparative computer simulation was carried out of the polymerization shrinkage forces of the composite material (CM), temperature changes in the oral cavity and functional masticatory loads. The distribution of the generated stress on the adhesive bond was evaluated in eight different class I and II cavity configurations. The location of crack formation was assessed in the cases of rupture of the adhesive bond. In all cavity configurations, stress concentration in the adhesive layer is higher at the interface with the dental tissues. Low temperatures (5 degrees C) generate forces that are greater than the strength of the adhesive bond in all studied cavity configurations. The distribution of the generated stresses under the effect of axial and tangent forces of 300 N is similar to that under the effect of temperature factors. The axial masticatory forces have a pronounced adverse effect on the adhesive bond in all cavity configurations. Low temperatures and axial masticatory forces play an important role for the marginal integrity. They exacerbate the adverse effects of polymerization shrinkage in composite restorations of masticatory teeth.Folia medica 53(4):60-5.