Antibiotic Prescribing Practices in Endodontic Infections: A Survey of Dentists in Serbia.

The study goal was to provide an overview of antibiotic prescribing practices of Serbian dentists when treating endodontic infections and to disseminate the current ESE (European Society of Endodontology) recommendations to the study participants. A link to an online questionnaire was sent to 628 Serbian dentists whose email addresses were publicly available on the Internet, 158 of whom responded to the survey, resulting in a 25.16% response rate. The significance of possible associations was assessed via the Chi-squared test and Cramer's V measure of association, with p < 0.05 considered as statistically significant. According to the study findings, 55.7% of respondents prescribed a 5-day antibiotic course. Moreover, Amoxicillin 500 mg was the first-choice antibiotic for 55.1% of the respondents, followed by Clindamycin 600 mg (18.4%). For patients allergic to penicillin, 61.4% of respondents prescribed Clindamycin. Statistically significant differences emerged only in relation to acute apical abscess with systemic involvement, whereby dentists aged 46-55 were least likely to prescribe antibiotics in these clinical situations (p = 0.04). Analyses further revealed that recommendations for safe antibiotic prescribing practices were not always followed, as in certain cases, patients were given antibiotics even when this was not indicated. These findings highlight the need for additional education on responsible antibiotic use to prevent bacterial resistance.

Application of Scanning Electron Microscopy in the observation of dentin-adhesive interface.

The objective of this study was observation of the adhesive interface on original tooth samples, as well as their epoxy replicas, under SEM. A light-cure flowable composite was incrementally placed and light-polymerized in previously prepared cylindrical dentinal cavities on the buccal surfaces of extracted human third molars. After finishing procedures, impressions of the composite/dentin margin were made using polyvinylsiloxane in order to obtain accurate epoxy replicas for SEM analysis. Ultrastructural morphology of the adhesive surface was observed at high magnifications (≥1,000×) on original tooth samples, which were previously prepared to expose the part of the dentin surface, which participates in the formation of adhesive bond. SEM micrographs showed that marginal adaptation was mostly of acceptable quality. In some of the SEM micrographs of original tooth samples, marginal gap formation, and resin tag breakdown were noted, which were ascribed to polymerization shrinkage. Profound understanding of ultrastructural morphology is necessary for achieving more predictable and durable margin between composite restorations and surrounding tooth structures, and SEM analysis can serve that purpose.

Improved marginal adaptation of composite restorations by using different placement and light polymerization techniques.

PURPOSE: To verify the influence of placement and polymerization technique on the gap width between dentin and composite restoration. METHODS: Standardized cylindrical cavities (3 mm in diameter, 2 mm deep) with all margins in dentin were prepared on buccal and oral surfaces of 30 extracted human third molars. With regard to the different resin composite filling techniques used, the samples were randomly divided into three groups (n=20): bulk; incremental; pin. Each group was further subdivided into subgroups based on different light polymerization techniques): continuous (40 seconds); discontinuous (2 seconds of activation, followed by 10 seconds of dark interval, then light polymerization continued for 38 seconds). After finishing procedures, impressions were made using polyvinylsiloxane, and epoxy resin replicas were obtained and prepared for scanning electron microscopy. The percentage of the marginal gaps in relation to the whole margin was recorded and statistically analyzed (P)≤ 0.05). RESULTS: Marginal adaptation of composite restorations placed into the dentin cavities using pin and discontinuously light polymerized presented significantly better results than other two tested groups polymerized in the same manner. CLINICAL SIGNIFICANCE: The proposed modified incremental placement technique with a transparent glass pin reduces marginal leakage at the interface between composite restoration and dentin; leakage which can jeopardize the longevity of the restoration.

The micromorphological characterization of adhesive bond in dentin different locations.

The aim of this study was to analyse the interfacial micromorphology of total-etch adhesives and dentin structures different locations by using SEM. Standardized cylindrical cavities (3mm in diameter, 2mm deep) with all margins in dentin were prepared on occlusal and buccal surfaces of twenty extracted human third molars. A total-etch dentin adhesive system and a light-cure flowable composite (Filtek Ultimate Flowable, 3M ESPE, St. Paul, MN, USA) were used in this study. Micro-morphological SEM analysis of the marginal seal of the original tooth specimens was performed using high magnification of up to 1000×. In this study, we found the difference in interfacial micromorphology in dentin different locations. Also, marginal gap was found in both observed dentin area. Better understanding of complexity and three- dimensional variations of the tooth structure is important for prevention of clinical challenges such as postoperative sensitivity, marginal discoloration and secondary caries, which could be prevented by achieving of predictable and long-lasting adhesive bond.

Viscoelastic properties of uncured resin composites: Dynamic oscillatory shear test and fractional derivative model.

OBJECTIVE: In this study we analyze viscoelastic properties of three flowable (Wave, Wave MV, Wave HV) and one universal hybrid resin (Ice) composites, prior to setting. We developed a mathematical model containing fractional derivatives in order to describe their properties. METHODS: Isothermal experimental study was conducted on a rheometer with parallel plates. In dynamic oscillatory shear test, storage and loss modulus, as well as the complex viscosity where determined. We assumed four different fractional viscoelastic models, each belonging to one particular class, derivable from distributed-order fractional constitutive equation. The restrictions following from the Second law of thermodynamics are imposed on each model. The optimal parameters corresponding to each model are obtained by minimizing the error function that takes into account storage and loss modulus, thus obtaining the best fit to the experimental data. RESULTS: In the frequency range considered, we obtained that for Wave HV and Wave MV there exist a critical frequency for which loss and storage modulus curves intersect, defining a boundary between two different types of behavior: one in which storage modulus is larger than loss modulus and the other in which the situation is opposite. Loss and storage modulus curves for Ice and Wave do not show this type of behavior, having either elastic, or viscous effects dominating in entire frequency range considered. SIGNIFICANCE: The developed models may be used to predict behavior of four tested composites in different flow conditions (different deformation speed), thus helping to estimate optimal handling characteristics for specific clinical applications.

Micromorphological characterization of adhesive interface of sound dentin and total-etch and self-etch adhesives.

INTRODUCTION: The ultimate goal in restorative dentistry has always been to achieve strong and permanent bond between the dental tissues and filling materials. It is not easy to achieve this task because the bonding process is different for enamel and dentin-dentin is more humid and more organic than enamel. It is moisture and organic nature of dentin that make this hard tissue very complex to achieve adhesive bond. One of the first and most widely used tools for examining the adhesive bond between hard dental tissues and composite restorative materials is scanning electron microscopy. The aim of this study was scanning electron microscopy analyzes the interfacial micro morphology of total-etch and self-etch adhesives. MATERIAL AND METHODS: Micro morphological characteristics of interface between total-etch adhesive (Prime & Bond NT) in combination with the corresponding composite (Ceram X Mono) were compared with those of self-etching adhesive (AdheSE One) in, combination with the corresponding composite (Tetric EvoCeram). The specimens were observed under 1000 x magnification of scanning electron microscopy (JEOL, JSM-6460 Low Vacuum). Measurement of the thickness of the hybrid layer of the examined com posite systems was performed with the software of the device used (NIH Image Analyser). RESULTS: Micromorphological analysis of interface showed that the hybrid layer in sound dentin was well formed, its average thickness being 2.68 microm, with a large number of resin tags and a large amount of lateral branches for specimens with a composite system Prime & Bond NT-Ceram X Mono. However, the specimens' with composite systems Adhese One-Tetric EvoCeram did not show the presence of hybrid layer and the resin tags were poorly represented. CONCLUSION: The results of this study suggest that total-etch adhesives bond better with sound dentin than self-etch adhesive.

Clinical features and endodontic treatment of two-rooted mandibular canines: report of four cases.

INTRODUCTION: Predictable endodontic treatment depends on the dentist's knowledge about root canal morphology and its possible anatomic variations. The majority of mandibular canines have one root and root canal, but 15% may have two canals and a smaller number may have two distinct roots. The following clinical reports describe endodontic treatment of mandibular canines with two roots and two root canals. OUTLINE OF CASES Four clinical case reports are presented to exemplify anatomical variation in the human mandibular canine. Detailed analysis of the preoperative radiographs and careful examination of the pulp chamber floor detected the presence of two root canal orifices in all canines. Working length was determined with an electronic apex locator and biomechanical preparation was carried out by using engine driven BioRaCe Ni-Ti rotary instruments in a crown-down manner, followed by copious irrigation with 1% sodium hypochlorite. Definitive obturation was performed using cold lateral condensation with gutta-percha cones and Top Seal paste. The treatment outcome was evaluated using postoperative radiographs. CONCLUSION: Endodontists should be aware of anatomical variations of the treated teeth, and should never presume that canal systems are simple.

Examination of the bioelectrical activity of the masticatory muscles during Angle's Class II division 2 therapy with an activator.

BACKGROUND/AIM: The muscles of the orofacial region have great influence on the development of dentition and occlusion formation. It is known that improper function of these muscles is one of the major etiological factors in malocclusion. A correlation between function disorders of orofacial muscle and occlusion disorders has been confirmed, as well as a correlation between the bioelectric activity of the masticatory muscles, recorded by electromyography, and bite force upon maximal voluntary contraction of these muscles. The aim of the study was to analyze the bioelectriacal activity of temporal and masseter muscles. METHODS: The sample consisted of 100 subjects of both sexes, divided into the control group (n = 30) with neutral and complete dental arches, and the study group (n = 70) of patients with distal occlusion. Electromyographic measurement of bioelectric potentials in all the subjects was conducted for the examined muscles in the physiologic rest position, central mandible occlusion, and during maximal voluntary contraction of muscles and saliva swallowing, in Angle Class I and II/2 occlusal relationships, prior to treatment, after one year of the orthodontic treatment and after the treatment with an activator. RESULTS: Comparing the values of the bioelectrical activity in the control and the study group before the treatment, a decreased muscle activity was established in all the three positions in the study group. After the first year of orthodontic treatment the results showed an elevation in the bioelectrical activity in both muscles. After treatment with an activator, the bioelectrical activity in both muscles in the study group was higher than before the treatment, as it is confirmed by a positive highly significant coefficient of correlation. CONCLUSION: In all the three measured positions of the mandible with Angle Class II/2 malocclusion, bioelectrical activity was lowest at baseline and increased during the first year of treatment, and at the end of the treatment it partially reduced close to the approximate values in normal occlusion. Research on electromyographic activity of masticatory muscles is useful in everyday clinical practice, especially in present distinctive skeletal discrepancy before, during and after orthodontic treatment, if on the bases of the results we can evaluate the treatment, but also determine the start and duration of the retention period and retention device type.

A model of the viscoelastic behavior of flowable resin composites prior to setting.

OBJECTIVE: The aim of this study is to develop fractional derivative models for the assessment of viscoelastic properties related to handling characteristics of dental resin composites belonging to two classes: flowable (Revolution Formula 2 and Filtek Ultimate) and posterior "bulk-fill" flowable base (Smart Dentin Replace). METHODS: Rheological measurements on all materials tested in this study were performed using dynamic oscillatory rheometer at temperature of 23°C. A parallel plates module with a diameter of 20mm was used to measure the properties of the resin composites tested. We developed two models to describe the obtained data: the generalized Newton model and the generalized Zener model (the so-called three parameter model). Both models contain fractional derivatives of Riemann-Liouville type. By determining the parameters of the model we were able to fit experimental data with high accuracy. RESULTS: Our results show that flowable "bulk-fill" resin-composite material (SDR) has distinct properties as compared to other two flowable resin composite materials (Revolution Formula 2 and Filtek Ultimate). Thus, previously found SDR properties as "bulk-fill" flowable base results in the fact that it is described by generalized Zener model (i.e., it has properties of solid like viscoelastic material). SIGNIFICANCE: Our model may be used to predict behavior of tested composites in different flow conditions. The SDR has initially small almost constant complex viscosity showing that it has good self-leveling property.

Crown reattachment with complicated chisel-type fracture using fiber-reinforced post.

INTRODUCTION: Maxillary incisors and specifically their crowns are the most common teeth involved in dental trauma because of their exposed position in the dental arch. Traumatized anterior teeth require quick functional and esthetic repair. In the case of a complex crown fracture, with the necessity of endodontic treatment, fiber-reinforced posts (FRC) were used to create a central support stump to restore the dental morphology. CASE REPORT: A 24-year-old male patient came to the dental clinic with dental injury to the maxillary left central incisor with a chisel-type fracture that extended subgingivally with a widely open pulp chamber. The patient reported a sports injury had occurred 1 day before. Provisional reposition of the crown was completed using a composite splint and after that endodontic treatment has been performed. Two days later, a fiber-reinforced composite resin post was placed into the canal and adhesive reattachment of the fragment also completed. The tooth was prepared for a composite resin veneer in the gingival third of the vestibular surface because of a visible fracture line. CONCLUSIONS: The combined use of a fiber-reinforced composite resin post and the original crown fragment is a simple and efficient procedure for the treatment of traumatized anterior teeth that appears to offer pleasing esthetic and functional results that is less invasive than conventional prosthodontic treatment.

Orthograde endodontic retreatment of teeth with individual cast posts: report of two cases.

INTRODUCTION: The failure of primary endodontic treatment is manifested by various clinical symptoms following endodontic therapy or, more frequently, by the development of chronic inflammatory process in the apex region without any subjective symptoms. In case of unfavorable outcome of the primary endodontic treatment, orthograde endodontic retreatment is the method of choice for a prolonged therapy. OUTLINE OF CASES: Two female patients, 47 and 44 years old, were presented at the Dental Clinic of Vojvodina for endodontic retreatment of teeth 22, 23 and 13, within the repeated prosthetic restoration. Intraradicular individual cast posts were removed using ultrasonic instruments. Remains of gutta-percha were removed by engine driven rotary re-treatment files, root canals were shaped and cleaned using the crown-down technique, and obturated with gutta-percha and epoxy-resin-based sealer using the lateral compaction technique. CONCLUSION: When there are metal posts or broken instruments in the root canal, the use of ultrasonic instruments is considered a safe method characterized by negligible tooth substance loss and minimal root damage causing fractures and perforations, and the entire procedure is effective and predictable. Non-surgical orthograde endodontic retreatment, when properly performed in accessible and penetrable root canals, achieves a high cure rate, good and lasting results and eliminates the need for radical procedures, such as apical surgery or tooth extraction. When nonsurgical endodontic retreatment is done, treated teeth must be restored by full coronal coverage as soon as possible, to prevent coronal leakage or fracture.

Predicting in vivo failure of rotary nickel-titanium endodontic instruments under cyclic fatigue.

The aim of this study was to examine the lifespan or number of cycles to failure of tapered rotary nickel-titanium (Ni-Ti) endodontic instruments. Simulated root canals with different curvatures were used to determine a relation between canal curvature and instrument lifespan. Using a novel mathematical model for the deformation of pseudoelastic Ni-Ti alloy, it was shown that maximum stress need not necessarily occur at the outer layer. On the basis of this observation, the Coffin-Manson relation was modified with parameters determined from this experiment. Results showed that the number of cycles to failure was influenced by the angle and radius of canal curvature and the size of instrument at the beginning of canal curvature. The resulting quantitative mathematical relation could be used to predict the lifespan of rotary Ni-Ti endodontic instruments under clinical conditions and thereby reduce the incidence of instrument failure in vivo.

[One-year clinical evaluation of compomer restorations in cervical lesions of different aetiology].

INTRODUCTION: The aim of this one-year prospective clinical study was to evaluate the treatment results of compomer restorations (Dyract eXtral Dentsply/De Trey, Konstanz, Germany) with a single step self-etching dental adhesive (Xeno III Dentsply/De Trey, Konstanz, Germany) used for restoring class V lesions (non-carious and primary carious cervical lesions). MATERIAL AND METHODS: A total number of 62 class V restorations (n = 62) were placed by one dentist in 30 patients on incisors, canines and premolars. The fillings were placed due to different indications: non-carious cervical defects (n = 32) and primary carious lesions (n = 30). The restorations were evaluated by a single-blind design, according to the Modified United States Public Health Service system 6 and 12 months following the placement. The following were evaluated: retention, marginal integrity, marginal discoloration, wear; postoperative sensitivity and secondary caries. The statistical analysis compared the ratings of each criteria between materials using the Pearson chi-square or Fisher's exact test at a level of significance of 5% (p < 0.05). RESULTS: Two restorations of the non-carious lesion group were lost after 6 months, and after 12 months one restoration was lost in the group of primary carious lesions. There were no statistically significant differences between restorations for all evaluated criteria in both groups. CONCLUSION: The compomer restorations in combination with a single step self-etching dental adhesive showed acceptable clinical performance in Class V lesions after one year of clinical service.

[One-year clinical evaluation of tooth-coloured materials in non-carious cervical lesions].

INTRODUCTION: The restoration of non-carious cervical lesions is specific, mostly because of the location of their margins, especially the cervical margin, which is determined in cement and/or dentine. This feature makes the cervical margin more susceptible to micro-leakage, causing marginal discoloration, postoperative sensitivity, development of the secondary caries and loss of the restoration. MATERIAL AND METHODS: One of the criteria for inclusion of a patient in this study was the presence of at least two non-carious cervical lesions to be restored with the minimum depth of 1 mm, independently of their location in the dental arch. A total of 60 restorations were placed in 30 patients. and every patient received both tested materials (composite resins and compomer) on their non-carious cervical lesions. The clinical evaluation of the therapeutic success was performed six months and then one year after the day of the placement of restorations using the modified-United States Public Health Service criteria. The following was evaluated retention, marginal integrity, marginal discoloration, wear, postoperative sensitivity and secondary caries. RESULTS: A statistically significant high percent of restorations/teeth with postoperative sensitivity was found in the group of resin composite restorations after six months. At the end of the evaluation period, that is after one year, there were no statistically significant differences between materials for all evaluated criteria. CONCLUSION: The results of this study show the identical quality of both examined materials one year after the readjustment of non-carious cervical lesions.

A method of improving marginal adaptation by elimination of singular stress point in composite restorations during resin photo-polymerization.

OBJECTIVES: To reduce the effect of stresses due to volumetric shrinkage the authors propose an incremental technique for placing composite restorations. METHODS: The goal of the method is to reduce the volume of the resin that is polymerized and eliminate a stress singular point in the resin that is positioned at the geometric center of the cavity. This is achieved by a two step type incremental technique. In the first step the resin is placed in the cylindrical cavity with a metal pin embedded in the middle of the composite restoration. After polymerization, the metal pin is removed and the cylindrical hole is filled with the second layer of composite. Finally, the second layer in the center of the composite restoration is polymerized. RESULTS: This study confirmed that the proposed incremental type placement technique reduces marginal debonding. SIGNIFICANCE: The main hypothesis is that the elimination of a stress singular point at the center of the restoration results in the reduction of stresses at tooth-composite interface and therefore improve the marginal adaptation (reduces length of the contraction gap at tooth-composite interface).

Microleakage of contemporary composite systems in dentin cavities.

This study evaluated microleakage in vitro of self-etch and multi-step, total-etch adhesive systems. Ninety extracted non-carious human molars were randomly assigned to nine groups (n=10) and restored with nine different composite systems: Gluma CPS/Charisma, Syntac Sprint/Tetric Ceram, 3M Single Bond/Silux, Admira Bond/Admira, Optibond Solo Plus/Herculite, Trendy Bond/Saremco, Excite/Tetric Ceram, Syntac Sprint/Compoglass and Promt-L-Pop/Silux. Cavities (2 mm diameter/2 mm deep) were prepared on the facial and lingual surfaces of each tooth previously abraded with a silicon-carbide abrasion discs to produce two level dentin surfaces with whole margins in dentin. Each group of composite systems was treated following the manufacturer's instructions. After they were finished and polished, the specimens were subjected to 100 thermal cycles in baths of 4 degrees +/- 2 degrees C and 58 degrees +/- 2 degrees C with 60 seconds of dwell time for each bath. After the thermocycling, the specimens were sealed with acid-resistant varnish, leaving a 1-mm window around the cervical margin interface, and immersed in 1% methylene blue buffered solution for 4 hours. Then the specimens were sectioned longitudinally in half and evaluated under stereomicroscopy at 30 times magnification, using inserted millimeter measurer. Each specimen was measured for dye penetration, thickness of composite filling and distance from the bottom ofcavity to the pulp chamber. The data were analyzed using Kruskal-Wallis Analysis of Variance (ANOVA) and Pearson t- test. Syntac Sprint/Tetric Ceram, 3M Single Bond/Silux, Admira Bond/Admira, Optibond Solo Plus/Herculite and Gluma CPS/Charisma showed the least microleakage at the occlusal part of the cavity. There was no significant difference of microleakage at gingival part of cavity for all tested composite systems and the best sealing ability showed 3M Single Bond/Silux. Self-etch and multi-step, total-etch adhesive systems showed more or less similar microleakage "in vitro" conditions and marginal sealing ability of all tested composite systems was significantly lower at gingival margins of cavities.

[Multi-factoriality of dentine hypersensitivity].

INTRODUCTION: Dentine hypersensitivity has been defined as a sharp, short pain arising from exposed dentin in response to stimuli typically thermal, evaporative tactile, osmoticor, chemical and which cannot be ascribed to any other form of dental defect or pathology. PREVALENCE: The most affected patients range in age from 20 to 40. The following teeth tend to be most sensitive: cuspids, premnolars and incisors, location-concentrated on the facial surface. MORPHOLOGICAL BASES OF DENTINE HYPERSENSITIVITY: Sensitive teeth have much greater numbers of open tubules per unit area and the average diameter of tubules is almost 2 times greater than tubules in nonsensitive teeth. MECHANISMS OF DENTINE HYPERSENSITIVITY: The most widely accepted theory of how the pain occurs is Brannstroms theory. ETIOLOGY: Dentine hypersensitivity represents a condition of presumable multifactorial pathology. Two processes are essential for its development: (1) dentin must be exposed through either genetic disturbance, enamel defect (lamellae, tufs and spindles), loss of enamel (erosion, abrasion, attrition, abfraction), gingival recession with rapid loss of cementum and (2) the dentin tubules must be open to both the oral cavity and the pulp. DIAGNOSIS: Diagnostic protocol for this condition consisted of Medical, Dental Dietary, Oral Hygiene History and Inra-oral examinations with air indexing method. Differential Dianosis: We must take into consideration a numnber of variables such as: dental caries, cracked tooth, restorative sensitivity, medication sensitivity, bleaching sensitivity and abscessed or non-vital tooth. CONCLUSION: Dentin hypersensitivity is a problem that bothers many patients. Many conditions share the symptoms of tooth sensitivity so differential diagnosis is essential for suitable treatment or preventive measures.