Assessment of Damage of Endodontic Instruments with Naked Eye and Optical Instruments.

OBJECTIVES: To determine the accuracy of visual damage evaluation of rotating and reciprocal endodontic instruments with the naked eye and optical devices. MATERIAL AND METHODS: Four examiners were involved, divided into two age groups: I. 20-30 years, n = 2, II. 40-50 years, n = 2. They visually assessed the existence of damage to rotating or reciprocal endodontic instruments by their naked eye and with two types of optical aids. A total of 239 instruments from different manufacturers were evaluated by each examiner. Before damage estimation, each examiner calibrated the eye on a new instrument. Sensitivity of the detection method was calculated as by the naked eye. When an instrument was detected as damaged by the naked eye, the damage assessment was stopped and the instrument was considered to be damaged by the other two methods, as well. RESULTS: Damage was found in 178 instruments. Sensitivity of the naked eye was calculated to be 49.7%, for the loupe 66.2% and for the operating microscope 76.5%. The three methods of damage assessment had significant differences (p < 0.05) in sensitivity. CONCLUSION: It was concluded that there is a significant difference between age groups in estimating instrument damage. Also, it was noted that the damage assessment with the naked eye and optical aids were different. Finally, in terms of ease of damage recognition, significant differences between the types of engine-driven endodontic instruments were found. However, no type of instrument was more prone to damage than any other type of instrument.

Molar Incisor Hypomineralization in Children with Intellectual Disabilities.

The aim of the study is to compare the frequency and the distribution of molar incisor hypomineralization (MIH) in children with intellectual disabilities. METHODS: Seventy-two children with intellectual disabilities and 72 healthy children were included in the study. They ranged in age from 5 to 18 years with the same distribution by age and sex. Standard clinical examination was performed, at a dental clinic or in the institution where the children lived, by using a dental mirror and a probe, according the European Academy of Paediatric Dentistry judgment criteria for MIH. RESULTS: Among the 72 children with intellectual disabilities, eight children (11.1%) presented MIH with 19 affected teeth. In the control group, one child (1.4%) presented MIH with two affected teeth. The difference was statistically significant (p = 0.033). There were no statistically significant differences between boys and girls. The molars, especially the first right molars were the most affected tooth. Brown defects were less common than white defects. CONCLUSION: Children with MIH should be identified because this condition is a common problem in children with intellectual disabilities.

Knowledge and Use of Caries Risk Assessment for Adult Patients Croatian Dentists.

OBJECTIVE: The aim of this study was to evaluate the usage of caries risk assessment (CRA) by Croatian general practitioners and evaluate their knowledge and attitudes towards CRA. MATERIAL AND METHODS: A link to an online questionnaire was sent via e-mail to a sample of 1,500 general dentists in Croatia. The obtained data were analyzed using descriptive statistics, logistic regression analyses and chi-square tests. RESULTS: Of 257 respondents, 47% performed CRA routinely, but only 4.5% of them used a specific CRA form. The significance of different factors in the development of a treatment plan varied considerably among respondents. Furthermore, in 77% of the respondents CRA was a basis for planning individual caries prevention (ICP). The association between CRA and ICP, and between CRA and treatment planning was statistically significant (p=0.001). The practitioners doing CRA more often plan their treatment and ICP according to CRA. The use of CRA was not influenced by specialty and dentists' experience. CONCLUSIONS: In a considerable percentage (53%) of Croatian general dentists, CRA is not part of their routine practice, and there is a strong association between the use of CRA and treatment plans and ICP. There is a need to promote the use of CRA in daily dental practice in Croatia.

Influence of different laser-assisted retrograde cavity preparation techniques on bond strength of bioceramic-based material to root dentine.

The purposes of the study were to evaluate the bond strength of bioceramic TotalFill root repair material (RRM) in retrograde cavities prepared using Er:YAG and Er,Cr:YSGG laser and steel bur, and to analyze failure modes. The root canals of 30 single-rooted teeth were endodontically treated, their root-ends were resected using a diamond bur, and the teeth were randomly divided into three groups (N = 10) according to the retrograde cavity preparation technique: (1) Er:YAG laser, (2) Er,Cr:YSGG laser, and (3) steel bur. All retrograde cavities were filled with the TotalFill RRM which was prepared according to the manufacturers' instructions. Push-out test was performed using universal testing machine, and failure mode was analyzed using a scanning electron microscope. The data were analyzed using one-way ANOVA, post hoc analysis with Bonferroni correction, and Fisher-Freeman-Halton exact test (p < 0.05). In the Er:YAG-, Er,Cr:YSGG-, and steel bur-prepared cavities, mean bond strengths (MPa) were 12.76, 8.44, and 6.01, respectively. The bond strength of the TotalFill RRM to dentin was significantly higher in the Er:YAG laser compared with the steel bur-prepared cavities (p = 0.004). The bond strength was not significantly different between the Er:YAG and Er,Cr:YSGG cavities (p = 0.074) and between the Er,Cr:YSGG and bur cavities (p = 0.648). In the cavities prepared by the Er,Cr:YSGG laser and bur, the failure mode of the TotalFill RRM was predominantly mixed, then adhesive and cohesive. In the Er:YAG laser-prepared cavities, the most common failure mode was adhesive, followed by mixed type and no cohesive failure. The bond strength of the TotalFill RRM to dentin was highest in the group of retrograde cavities prepared by the Er:YAG laser.

Mechanical Properties of High Viscosity Glass Ionomer and Glass Hybrid Restorative Materials.

OBJECTIVES: to determine the mechanical properties of hybrid and high-viscosity glass ionomer cements. Compressive strength and hardness of three glass ionomer cements (GIC) were measured: Ketac ™ Universal Aplicap ™, EQUIA Fil® and EQUIA FORTE Fil®, and the SEM sample analysis were performed. MATERIALS AND METHODS: The samples for measuring the compressive strength were prepared using silicone molds with standard dimensions of 6 mm x 4 mm and stored in deionized water for five days, while the samples for hardness measurement were prepared using Teflon molds with a cylindrical opening in the middle, dimensions 2 mm in height and 5 mm in width. For each material, one sample was made (n = 1) and stored in deionized water at 37ºC for 25 days. A representative sample of each material was analyzed using SEM. For the comparison of obtained values, the ANOVA test was used, while Tukey test was used for the multiple comparison. RESULTS: There were no significant differences between the compressive strength of the three tested materials (p <0.05). The hardness values were: 157 HV0,2 for Ketac ™ Universal Aplicap ™, 47 HV0,2 for EQUIA Fil® and 39 HV0,2 for EQUIA FORTE Fil®, respectively, and were significantly different, implying that Ketac ™ Universal Aplicap ™ has much higher hardness values than the other materials tested. SEM sample analysis revealed similar fracture modes of the tested materials. CONCLUSION: It was concluded that there were no statistically significant differences in compressive strength and fracture modes between the tested materials, while Ketac ™ Universal Aplicap ™ hardness results were significantly higher than the ones measured for EQUIA Fil® and EQUIA FORTE Fil®.

Clinical and Radiographic Assessment of Cases Referred to Endodontic Surgery.

OBJECTIVE: The objective of the study was to assess the quality of root canal fillings of cases referred to endodontic surgery using preoperative radiographs and correlate it with endodontic surgery treatment decision. The objective was also to analyse clinical symptoms and size of periapical lesions on radiographs and correlate them with treatment decisions including non-surgical retreatment, endodontic surgery and extraction. MATERIALS AND METHODS: A questionnaire was composed to record the data. Eighty-six patients with 109 teeth, who were referred to endodontic surgery, participated in the research. The quality of root canal filling was assessed according to its homogeneity and filling length on digital radiographs. The data were analyzed using χ2-test and t-test. RESULTS: Of the teeth referred to endodontic surgery, 97.2% were treated by a general practice dentist, endodontic retreatment was attempted in 20.6%, and root canal filling was homogeneous and within 1 mm from the apex in 21.6%. Endodontic surgery, retreatment, extraction and no treatment were selected in 90.1%, 5.4%, 1.8% and 2.7% of the cases, respectively. CONCLUSIONS: Low percentage of adequate root canal fillings and high percentage of endodontic surgery decisions suggest that there is a need to increase awareness of non-surgical retreatment options.

Compressive Strength of New Glass Ionomer Cement Technology based Restorative Materials after Thermocycling and Cyclic Loading.

OBJECTIVE: The objective of the study was to compare compressive strengths of two glass ionomer-based materials, with and without a light-cured, nano-filled coating, after cyclic loading and thermocycling. MATERIALS AND METHODS: To determine compressive strength of new restorative materials over a longer period of time, materials were analysed under simulated conditions where cyclic loading replicated masticatory loading and thermocycling simulated thermal oscillations in the oral cavity. Four groups of samples (n=7)-(1) Equia Fil (GC, Tokyo, Japan) uncoated; (2) Equia Fil coated with Equia Coat (GC, Tokyo, Japan); (3) Equia Forte Fil (GC, Tokyo, Japan) uncoated; and (4) Equia Forte Fil coated with Equia Forte coat (GC, Tokyo, Japan)-were subjected to cyclic loading (240,000 cycles) using a chewing simulator (MOD, Esetron Smart Robotechnologies, Ankara, Turkey). RESULTS: Compressive strength measurements were performed according to ISO 9917-1:2007, using the universal mechanical testing machine (Instron, Lloyd, UK). Scanning electron microscope (SEM) analysis was performed after thermocycling. There were no statistically significant differences between Equia Fil and Equia Forte Fil irrespective of the coating (p<0.05), but a trend of increasing compressive strength in the coated samples was observed. CONCLUSIONS: Coating increases the compressive strength of Equia Fil and Equia Forte Fil, but not significantly.

Electric pulp test threshold responses in healthy incisors, canines, premolars and molars.

The purpose of this study was to determine the range of threshold responses of healthy dental pulps and test the reproducibility of the electric pulp test (EPT). Forty-nine dental students participated in the study. Sound teeth in both arches, except third molars, were included. The teeth were isolated using cotton rolls and dried with compressed air, and the threshold responses were recorded. Participants stopped the stimulus increase by pressing the switch at the first sensation of discomfort. The measurements were repeated after 30 days. The obtained data were analysed using SPSS® 16.0. The mean thresholds for the maxillary incisors, canines, premolars and molars were 10.77, 21.07, 21.88 and 34.07 µA, and for mandibular incisors, canines, premolars and molars 9.81, 18.7, 19.24 and 30.1 µA respectively. The differences between the two measurements were statistically significant for teeth 32, 31, 41 and 42. The EPT was shown to be reproducible for all the teeth tested except mandibular incisors.

Push-out bond strength of three different calcium silicate-based root-end filling materials after ultrasonic retrograde cavity preparation.

OBJECTIVE: The aim of this study was to evaluate the bond strength of three calcium silicate-based root-end filling materials. MATERIALS AND METHODS: The root canals of 30 single-rooted teeth were endodontically treated; their root ends were resected and root-end cavities were prepared using ultrasonic tip. The teeth were randomly divided into three groups according to the material: (1) Micro-Mega mineral trioxide aggregate (MM-MTA), (2) Biodentine, and (3) TotalFill root repair material (RRM). Push-out test was performed using universal testing machine, and failure mode was analyzed by stereomicroscope. The data were statistically analyzed using Kruskal-Wallis and Man-Whitney post hoc tests. All p values < 0.05 were considered significant. RESULTS: TotalFill RRM exhibited significantly higher bond strength (12.69 MPa) than Biodentine (9.34 MPa, p = 0.023) and MM-MTA (7.89 MPa, p = 0.002). The difference between Biodentine and MM-MTA was not significant (p = 0.447). Mixed failures were the most noted in all three groups. MM-MTA had more adhesive failures than Biodentine and TotalFill, and no cohesive failures, but without statistical significance (p = 0.591). CONCLUSION: The bond strength was the highest for TotalFill RRM. CLINICAL RELEVANCE: In order to provide a persistent apical seal, root-end filling materials should resist dislodgement under static conditions, during function and operative procedures. TotalFill RRM exhibited higher bond strength to dentin than MM-MTA and Biodentine.

Self Assessment of Dental students' Perception of Learning Environment in Croatia, India and Nepal.

AIM: The aim of this study was to assess dental students' perception of different learning environment in India, Nepal and Croatia. METHODS: The study was conducted during a period of academic year 2016/17. A total of 849 dental students participated in the study. There were 188 respondents from Croatia, 373 from India, and 288 from Nepal. Non-responders were not followed up. The Dental Student Learning Environment Survey (DSLES) was used which consisted of 55 items subdivided into seven scales. The scales measured the following perceptions: Flexibility, 'Student-to-Student Interactions, Emotional Climate, Supportiveness, Meaningful Experience, Organization and Breadth of Interest. Statistical analysis of the data utilised the Kolmogorov Smirnov test. The Kruskal-Wallis "non-parametric ANOVA" was also used to test the differences between the countries. A post hoc analysis was performed using Ranks tables and the Median test. RESULTS: The response rate was 26.9%. Significant differences between the countries were found for all DSLES variables (Kruskal-Wallis, p<0.01). The Median test also showed significant differences between the countries for all DSLES variables (p<0.01). The scales with the highest mean values were 'Student-to-student interactions' in India and Nepal, and the 'Emotional Climate' in Croatia. CONCLUSIONS: Students in Croatia rated their school only with grades excellent and good, while their colleagues in India and Nepal were more critical. Despite the different settings in three countries, 'Flexibility' was identified as the area of weakness in all three educational systems.

Fluoride Release from Glass Ionomer with Nano Filled Coat and Varnish.

OBJECTIVE: This in vitro study compares the fluoride release from microlaminated glass ionomer based on glass hybrid technology coated with two different surface coating agents. MATERIALS AND METHODS: A total of 18 samples were divided into three groups of six samples each: (1) glass ionomer Equia Forte Fil coated with Equia Forte Coat (Equia+EC), (2) glass ionomer Equia Forte Fil coated with GC Fuji Varnish (Equia+VC) and (3) uncoated glass ionomer Equia Forte (EQUIA cont). Fluoride release was measured using an ion-selective electrode (ORION EA 940) after 24 hours, 4 days, 30 days and 64 days. Repeated measures ANOVA, multiple comparisons, Tukey's test and paired t-test were used to test the differences between the groups. RESULTS: The differences between the groups and four time points were statistically significant (ANOVA, p<0.0001). Cumulative fluoride ion release after 64 days was 66.01 mg/l, 123.54mg/l and 203.22 mg/l for EQUIA+EC, EQUIA+VC and EQUIA cont, respectively. All the differences were statistically significant except the difference between EQUIA+VC and EQUIA cont after 24 hours. CONCLUSIONS: The amount of released fluoride was significantly lower in the samples coated with nanofilled surface coating agent compared to the samples coated with varnish and uncoated samples.

Frequency of bacetrial content finding in persistant periapical lesions.

OBJECTIVES: To determine the percentage of persistant apical lesions positive for bacterial nucleic acids, to detect microorganisms difficult to cultivate in persistant apical lesions by PCR and relate them to endodontic failure, clinical symptoms and diabetes mellitus. MATERIALS AND METHODS: The samples of persistent apical lesions were collected during apicoectomy. Bacterial ubiquitous primer 16S rRNA was used to detect 16S ribosomal RNA in 36 samples. A species-specific PCR was performed with primers targeted to the bacterial 16S rRNA genes of Prevotella Nigrescens, Pseudoramibacter alactolyticus, and Propionobacterium propionicum. RESULTS: Six samples (16.67%) were positive for bacterial ribosomal RNA. Pseudoramibacter alactolyticus was detected in three samples. Propionibacterium propionicum and Prevotella nigrescens were detected in one sample each. The prevalence of infection of such lesions with P. intermedia, P. propionicum and P. alactolyticus is low. CONSLUSION: The study we conducted gave insufficient data about extraradicular infection and its connection with diabetes mellitus and clinical symptoms. CONCLUSIONS: Apical lesions persisting after endodontic treatment could harbor microorganisms other than Actinomyces and Propionicum species.

Adverse Effects of Antiepileptic Drug Lamotrigine and Oral Implications: Case Report.

Here, we report on a patient who presented with extensive oral lesions. The treatment with lamotrigine is described.The patient presented with bilateral facial swellings and mental space swelling with actively draining extra oral sinus tract in the central chin area. Dental medicine professionals should be aware of the risks involved with using this medication, and should recognize the population at risk among patients suffering from epilepsy, bipolar and neurologic disorders.

Efficacy of Three Different Lasers on Eradication of Enterococcus faecalis and Candida albicans Biofilms in Root Canal System.

OBJECTIVE: The objective was to compare the efficacy of three different lasers in disinfection of root canals inoculated with Enterococcus faecalis and Candida albicans biofilms. BACKGROUND: Endodontic space disinfection depends on the type of root canal irrigant used and the way it is delivered and agitated because irrigants have limited ability to reach all parts of root canal system. MATERIALS AND METHODS: Thirty single-rooted human teeth were selected. Root canals were instrumented and root surfaces were sealed using adhesive and the apical openings with adhesive and composite resin. Roots were fixed in Eppendorf tubes and sterilized in autoclave. The specimens were randomly divided into three experimental groups (n = 10) and inoculated with E. faecalis and C. albicans. After 7 days of incubation period, the number of E. faecalis and C. albicans colony-forming units (CFUs) was determined for each root canal. In the first experimental group, Er:YAG laser (0.3 W) with photon-induced photoacoustic streaming technique was used for root canal disinfection, in the second, Nd:YAG laser (1.5 W), and in the third, Er,Cr:YSGG (1.25 W) laser was used. After different root canal disinfection protocols, the number of E. faecalis and C. albicans CFUs was determined again for each root canal. RESULTS: Er:YAG and Er,Cr:YSGG lasers eradicated significant number of E. faecalis and C. albicans CFUs (p < 0.05), while Nd:YAG laser irradiation did not result in statistically significant reduction (p > 0.05). Er,Cr:YSGG laser eradicated significantly more microorganisms in comparison with Er:YAG laser (p < 0.05). CONCLUSIONS: Er,Cr:YSGG laser was the most efficient tool in eradication of E. faecalis and C. albicans biofilms.

Knowledge, Attitudes and Habits Regarding Oral Health in First- and Final-Year Dental Students

The purpose of the research was to compare oral health behavior and plaque indices between Croatian first-year and final-year dental students. Therefore, 46.9% of first-year and 47% of final-year dental students were surveyed using the Hiroshima University Dental Behavior Inventory (HU-DBI) questionnaire and had their plaque indices determined. Descriptive statistics analysis, nonparametric tests, and correlation analysis were performed (p<0.05). Sixth-year students had a significantly better mean HU-DBI score (8.06) than first-year students (6.45). Significantly more first-year students thought that they could not help having false teeth at their old age (p=0.007), had never been taught professionally how to brush (p=0.019), and used a toothbrush with hard bristles (p=0.001). Significantly more final-year students brushed each of their teeth carefully (p=0.008), thought they could clean their teeth well without using tooth paste (p=0.000), used a dye to see how clean their teeth were (p=0.002), and had their dentist telling them they brushed very well (p=0.028). Plaque index values were significantly lower (p<0.05) among first-year (7.94±0.72) than among final-year (9.13±0.77) students. With advancement in dental training, oral health attitudes improved, but the level of dental students' oral hygiene decreased.

Radiomorphometric indices of mandibular bones in an 18th century population.

OBJECTIVE: To estimate four radiomorphometric indices of mandibular bones in an 18th century population sample, and possibly associate the findings with bone mass loss related to sex, age, nutritional habits and pathologies reflecting on the bone. DESIGN: Thirty-six sculls (31 males, 5 females), recovered from the crypt of Pozega Cathedral in Croatia were analyzed. Age estimation was based on tooth wear, and Eichner class was determined according to the number of occlusal supporting zones. The parameters in recording analogue orthopantomographs were set to constant current of 16 mA, exposure time of 14.1s, and voltage between 62-78 kV. Films were processed in an automatic dark chamber processor for 12 min, and digitized at 8-bit, 300 dpi. The thickness of the mandibular cortex was assessed below the mental foramen (MI), at antegonion (AI), at gonion (GI). Qualitative mandibular cortical index (MCI) was assessed. RESULTS: Average values of MI, AI and GI were 3.97 ± 0.94 mm, 2.98 ± 0.56 mm, and 1.99 ± 0.55 mm, respectively. Statistically significant differences between males and females were found for AI right (p=0.014), GI left (p=0.010) and GI average (p=0.006), and were in all cases higher in males. There were no statistically significant differences between age groups for either index (p>0.05). Considering Eichner classification the differences were not significant for MI (p=0.422), AI (p=0.516), and GI (p=0.443), but in Eichner classes II, MCI was significantly higher (p=0.02). CONCLUSION: The obtained data does not suggest generalized malnutrition or calcium, phosphorus and vitamin D deprivation in the historic population studied.

Proteomics profiling of keratocystic odontogenic tumours reveals AIDA as novel biomarker candidate.

BACKGROUND: Keratocystic odontogenic tumour (KCOT) is a benign, yet aggressive odontogenic tumour. Herein, proteome analysis of KCOT lesions in comparison with control patient-matched tissue unaffected by the disease and with inflammatory odontogenic cysts, namely radicular cysts is presented. METHODS: For the proteomics profiling, two complementary proteomics techniques MALDI-MS/MS and LC-ESI-MS/MS were employed. Potential candidate biomarkers were validated by immunohistochemistry. RESULTS: More than 43 proteins were found to be differentially expressed or up-regulated in KCOT lesions in comparison with patient-matched unaffected oral mucosa. These proteins bear important biological functions and are involved in cell proliferation, cytoskeletal re-organization, transcription, cellular motility and apoptosis. In particular, a number of differentially expressed proteins participate in autocrine regulation and signalization within JNK and p38 MAPK signalling pathways. CONCLUSIONS: Immunohistochemical validation of chosen putative biomarkers revealed axin interaction partner and dorsalization-antagonist (AIDA), known as a protein that blocks activation of JNK signalling pathway, as a differential biomarker for KCOT lesions on an independent cohort of KCOT tissue samples in comparison with most prevalent intra-oseal lesions inflammatory odontogenic cysts.

The effects of bluephase LED light on fibroblasts.

OBJECTIVE: The aim of this study was to evaluate the effect of Bluephase light emitting diode (LED) light on cell viability, colony-forming ability and proliferation in V79 cell culture and to determine how much the temperature of the nutrient medium rose. METHODS: The investigation included a low (L), soft start (S) and high (H) illumination mode for 20, 40 and 80 seconds. The viability was determined by the trypan blue exclusion test, colony-forming ability by counting colonies 7 days after exposure and cell proliferation by the cell counts on 5 post-exposure days. The temperature change during illumination was recorded (0.1°C sensitivity). RESULTS: In each experimental condition, 90-95% of the cells were viable, which was in the same range as the controls. Colony-forming ability was not found to be significantly lower (P<.05). A significant decrease in proliferation was recorded on the 4th post-exposure day with S and H irrespective of time, on the 3(rd) day with S for 80 s and H for 40 and 80 s, and with S and H for 80 s on the 2(nd) day (P<.05).The temperature rise was significant with S (P<.05) and H (P<.05), irrespective of exposure duration. CONCLUSION: Dependent on total energy density, LED blue light affects the mitotic activity of cells in its path to a certain extent. Altered mitotic activity was not noted with illumination at the low power mode (intensity of 421.7 ±1.1 mW/cm(2)). The greatest temperature rise was 8.3 °C and occurred at the highest intensity and exposure duration.

Caries prevalence and periodontal status in 18th century population of Pozega-Croatia.

OBJECTIVE: The aim was to examine dental and periodontal status of adult Croatian 18th century population and compare the results with available literature data. MATERIALS AND METHODS: 104 specimens from the crypt of Pozega cathedral were grouped into three female and three male groups according to age. Caries was determined by visual inspection and dental probe. Ante and post mortem teeth losses were recorded. Periodontal status was determined according to the length of exposed tooth root from alveolar crest to cemento-enamel junction. The presence of dehiscences and fenestrations was recorded on facial and oral plate of alveolar bone. RESULTS: The whole sample exhibited ante- and post mortem teeth loss of 19.57% and 24.91%, respectively. The teeth most frequently lost postmortem were incisors. The canines were best preserved. The frequency of caries in both jaws was the highest in molars (26.63% in maxilla and 28.10% in mandible), whilst central incisors exhibited the least carious lesions (11.59 and 1.92%). The most frequently affected surfaces were occlusal, then proximal and facio-oral. The percentage of teeth with either moderate or considerable bone loss was higher in females. The frequency of considerable bone loss increased significantly with age. The frequency of dehiscences was 3.11%. It was higher in maxilla than in the mandible. The frequency of fenestrations was 5.65% and it was significantly higher in maxilla. CONCLUSIONS: The results demonstrate poor oral health amongst 18th century population of continental Croatia, exhibiting high antemortem teeth loss, high periodontal disease frequency and occlusal and proximal caries frequency.

Dose- and mode-dependent effect of halogen dental curing blue light on the V79-cell line.

The aim of this study was to evaluate the time and dose dependent effect of halogen light from dental curing unit on the cell viability, colony-forming ability and proliferation of the V79 cell culture. The investigation included the medium mode (M), exponential (E) and standard (S) illumination mode for 20, 40 and 80 seconds. The viability was determined using the trypan blue exclusion test. Colony forming ability was assessed by colony count on post-exposure day 7. Cell proliferation was determined by cell counts during five post-exposure days. The viability of cells was not affected by blue light in view of exposure time and modes. Colony forming ability in treated cells was slightly, but not significantly lower than in control cells. Cell proliferation was lower in cells exposed to the M mode for 80 s on post-exposure day 3 and 4 (p < 0.05). On the same post-exposure days, the proliferation of cells exposed to modes E and S, showed a significant inhibition after 20, 40 and 80 s of exposure (p < 0.05). Disrupted cellular functionality and no significant decrease in colony forming ability of V79 cells in addition to time- and dose dependent significant inhibition of cell proliferation might be ascribed to the photocuring blue light activity and/or changes in temperature during the course of experiment in vitro.