The effect of sealer type and obturation technique on the fracture resistance of endodontically treated roots

OBJECTIVE

This study evaluated the effect of sealer type with various obturation techniques on the fracture resistance of root filled teeth.

MATERIALS AND METHODS

Eighty mandibular premolars were collected, and root canals of 70 of them were prepared by Mtwo system up to 40/04. Thirty teeth were obturated using TotalFill BC sealer, and 30 using AH Plus sealer, with one of the obturation techniques (N = 10), namely cold lateral compaction (CLC), warm vertical compaction (WVC), and single cone (SC). Ten teeth were left without obturation as a positive control, and the other 10 teeth were not prepared serving as a negative control. Teeth were stored for 3 weeks, and the crowns were separated and the roots were subjected to fracture test using a universal testing machine.

RESULTS

Data was analyzed by ANOVA followed by Tukey's test. Fracture resistance of the TotalFill groups was significantly higher than the AH Plus groups in each obturation technique, and SC had the highest fracture resistance regardless of sealer used (P < 0.05). Obturation of the root canal by TotaFill BC sealer increased the calcium/phosphorous ratio in the dentin of the root.

CONCLUSIONS

Obturation with TotalFill BC sealer improved the fracture resistance of the roots more than AH Plus sealer, and obturation with SC resulted in higher fracture resistance than CLC and WVC.

CLINICAL RELEVANCE

Obturation of the root canal with Bioceramic sealer with single cone obturation technique could reduce the incidence of vertical root fracture.

Reframing perceptions in operative dentistry relating evidence-based dentistry and clinical decision making: a cross-sectional study among Jordanian dentists

BACKGROUND

The aim of the current study was to investigate current dental practice in operative dentistry in Jordan, and the relationship between evidence-based dentistry in caries research and decision making in clinical practice in operative dentistry.

MATERIALS AND METHODS

This cross-sectional study was conducted through a survey of dentists in Jordan. The survey aimed to explore the degree of knowledge and practice of evidence-based dentistry in caries research the dentists possess regarding clinical decision making in operative dentistry. The sample size was composed of (5811) dentists whom registered in Jordan Dental Association database. Descriptive statistics were generated and Chi-square test was used to examine associations between the different variables and the significance level was set at P < 0.05.

RESULTS

4000 responses were collected from the web-survey, response rate (68.83%). Nearly half of the surveyed dentists focus on the chief complaint of their patients (n = 2032, 50.8%) rather than doing full mouth assessment. Nearly two-thirds of dentists (n = 2608, 65.2%) treat lesions confined to enamel with operative treatment. Half of dentists use operative treatment when asked about the routine management of radiographically detected proximal caries confined to enamel. When treating incipient lesions, the majority (n = 3220, 80.5%) use preventive treatment. Three-quarters of dentists (n = 2992, 74.8%) treat deep dentinal caries by removing just the soft infected carious dentin, and treated old failed restorations with replacement.

CONCLUSION

In operative dentistry, the evidence-based research is not implemented clinically. To optimize relationship between evidence-based dentistry and clinical decision-making, dental curriculum has to be updated and modified constantly.

The effect of different calcium silicate-based pulp capping materials on tooth discoloration: an in vitro study

Background

Variation in the composition of calcium silicate-based pulp capping materials could influence the discoloration potential of some of these materials, thus affecting the color and aesthetic appearance of the coronal tooth structure. Furthermore, contact with blood if hemostasis is not fully achieved may enhance this discoloration for some materials. Therefore the aim of this study was to evaluate in vitro the color change of coronal tooth structure after placing various calcium silicate-based materials in the pulp chamber in the presence or absence of blood.

Mehtods

Maxillary extracted premolars (n = 144) were sectioned and the crowns were separated from the roots. Pulp chambers were prepared to a standard size and then the tested materials (GMTA Angelus, ProRoot WMTA, Biodentine, TheraCal, and TotalFill) were placed with saline or with blood. Color change was assessed by spectrophotometry; prior to and after material placement at different time intervals of 24 h, 1 week, 1 month, 3 months, and 6 months. Color change (ΔE) values were calculated and statistically analyzed.

Results

In the saline groups, Biodentine caused the least color change, while GMTA and WMTA caused the highest color change which were significantly different from the others (p < 0.001), TotalFill and TheraCal caused moderate changes. Adding blood increased the ΔE overall the tested materials to various degrees. Biodentine was the most affected by the blood, while MTA groups were the least affected, followed by TotalFill and then TheraCal. The increase in ΔE was significant over time up to 3 months, after which the increase was not significant.

Conclusions

Overall, WMTA and GMTA caused the most severe discoloration. In saline, Biodentine caused the least discoloration, but it was the most affected by the presence of blood, although it still caused the least discoloration similar to that observed with TotatFill. TheraCal caused moderate discoloration but more than that caused by Biodentine and TotalFill.

The effect of calcium hydroxide on dentine composition and root fracture resistance of human teeth: An in vitro study

The purpose of this study was to evaluate the effect of calcium hydroxide [Ca(OH)₂ ] on dentine composition and root fracture resistance. Root canals of fifty extracted mandibular premolars were prepared and divided into five groups (N = 10). Canals were filled with non-setting Ca(OH)₂ or left empty and were subsequently stored in phosphate buffered saline for 7, 14, 30, or 90 days, respectively. Ca(OH)₂ was then washed out, and roots were separated from the crowns and subjected to fracture strength test. Fractured fragments were examined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results showed a significant and progressive reduction in fracture resistance the longer the duration of exposure to Ca(OH)₂ , and the fracture resistance in teeth exposed for 90 days was significantly lower than in any other group. SEM revealed cracks in the dentine surfaces that had been exposed to Ca(OH)₂ . FTIR showed a significantly lower mineral to matrix ratio in roots exposed to Ca(OH)₂ for 30 and 90 days than seen in roots exposed for a shorter duration. XRD analysis revealed a reduction in dentine crystallinity. It was concluded that Ca(OH)₂ significantly reduced the fracture resistance of the roots overtime. Exposure to Ca(OH)₂ reduced the mineral to matrix ratio and crystallinity of the dentine.

The effect of adding graphene oxide nanoplatelets to Portland cement: Potential for dental applications

Background:

The potential of graphene-based materials to improve the physiomechanical properties of Portland cement-based materials without compromising biocompatibility is of interest to dental researchers and remains to be discovered.

Aim:

This study investigated the effects of adding graphene oxide nanoplatelets (GONPs) on the surface microhardness and biocompatibility of Portland cement.

Materials and Methods:

Three prototype Portland cement powder formulations were prepared by adding 0, 1, and 3 wt % GONPs in powder form to Portland cement. Prototype cement specimens were in the form of disks, with a diameter of 10 mm and a thickness of 2 mm. In experiment 1, surface microhardness was measured using the through indenter viewing hardness tester, 20 surface hardness values were obtained from all specimens. In experiment 2, Balb/C 3T3 fibroblasts were cultured with the material disks and the viability of cells was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.

Statistical Analysis:

The data were analyzed using the analysis of variance followed by Dunnett test (α = 0.05) or Tukey test (α = 0.05).

Results:

In response to material disks, the addition of 1 wt % GONPs had a proliferative effect on cells at day 3 and day 7 with a significant difference from the control. The addition of 3 wt % GONPs showed a remarkable increase in surface microhardness; however, it exhibited initial cytotoxicity.

Conclusions:

The addition of 1 wt % GONPs to Portland cement improved surface microhardness without compromising biocompatibility; therefore, it has a greater potential for dental applications. The results of this work give other researchers leads in future assessments of this prototype material.

Comparison of the Photosensitivity of Biofilms of Different Genera of Cariogenic Bacteria in Tooth Slices

This study compared the outcome of photosensitization on the viability of four different cariogens in planktonic form as well as biofilms in human dentine. Photodynamic therapy was carried out with a gallium aluminium arsenide laser (670 nm wavelength) using Toluidine blue O (TBO) as the photosensitizer. Cariogenic bacteria (Streptococcus mutans, Lactobacillus casei, Streptococcus salivarius and Actinomyces viscosus) were exposed to TBO and then to the laser for 1 minute in planktonic suspension. Then, tooth slices previously incubated for 24 hours with broth cultures of broth culture of the four cariogenic organisms were exposed to antimicrobial photosensitization. The control samples consisted of planktonic and sessile cells that were exposed to TBO alone, laser alone and the bacterial cells that were not treated with TBO or laser. The results showed significant reductions in the viability of S. mutans, L. casei and A. viscosus in both planktonic form (to 13%, 30%, and 55%, respectively) and sessile form hosted in dentinal tubules (to 19%, 13% and 52%, respectively), relative to the controls. S. salivarius was the least affected in planktonic (94% viability) and sessile form (86% viability). In conclusion, sensitivity to photosensitization is species-dependent and sessile biofilm cells are affected to the same extent as their planktonic counterparts.

Biocompatibility evaluation of Jordanian Portland cement for potential future dental application

Background

The demand for novel Portland cement (PC)-based formulations to be used in dental applications is ever increasing in viewing the foregoing knowledge on the favorable effects of these formulations on cellular proliferation and healing, leading to treatment success.

Aim

This study investigated the effect of white and gray mineral trioxide aggregate (W-MTA and G-MTA) and white and gray Jordanian PC (W-PC and G-PC) in their raw state on the viability of Balb/C 3T3 fibroblasts using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

Materials and Methods

Materials were prepared in the form of disks, with a diameter of 5 mm and a thickness of 2 mm. In the first experiment, Balb/C 3T3 fibroblasts were cultured with the material disks using culture plate inserts. In the second experiment, material elutes were added to cultured cells. The elutes were prepared by adding 2 ml serum-free media to 10 disks of each material and then incubated at 37°C for different time intervals. Material elutes were analyzed using ion chromatography for traces of calcium. The data were analyzed using analysis of variance followed by Dunnett test (α = 0.05) or Tukey test (α = 0.05).

Results

In response to material disks, G-PC had a proliferative effect on cells at day 1 and day 2 with a significant difference from the control at day 1. G-MTA reduced cell viability with a significant difference from the control level at day 2. Elutes of PC showed biocompatible and even proliferative effects on Balb/C 3T3 fibroblasts. Calcium ions were found to leach continuously over the measurement period for all the materials tested in this work.

Conclusion

Jordanian PC in its raw state was found to be biocompatible, and the results of this work give promise of its wider use as a base for further development to improve the physiochemical and mechanical properties of the material.

Correlation of Dental and Skeletal Malocclusions in Sagittal Plane among Saudi Orthodontic Patients

AIM

Whether or not the dental relationship correlates with skeletal relationship in the sagittal plane is an area of interest for orthodontic diagnosis and treatment planning. Thus, the aim of this study was to investigate the correlation of the dental malocclusion and the skeletal malocclusion in the sagittal plane among Saudi orthodontic patients.

MATERIALS AND METHODS

Orthodontic dental casts and cephalometric radiographs of 124 patients were investigated and analyzed. The dental casts were classified in relation to the molar relationship according to Angle's classification and to the incisal relationship according to the British Standards Institution (BSI) classification. The sagittal relation in the cephalometric radiographs was analyzed according to ANB angle and WITS appraisal.

RESULTS

The results show that the incisal relation had a very high significant association with WITS appraisal (p = 0.0045), whereas with ANB, the association was marginally significant (p =0.0528). No significant associations were found with molar relation neither at ANB (p = 0.2075) nor at the WITS (p = 0.4794) appraisal. Significant positive correlations between ANB and WITS appraisal were found at the three incisal classification classes (class I, r = 0.73; class II, r = 0.64; class III, r = 0.75) and no significant correlation was observed in all classes with the Angle's (molar) classification.

CONCLUSIONS

The incisal classification had a significant association with WITS appraisal, whereas with ANB the association was marginally significant. No correlation was found between Angle's (molar) classification and ANB or WITS appraisal.

CLINICAL SIGNIFICANCE

The incisal relation could be considered as a good indicator of the skeletal malocclusion in the sagittal plane in the orthodontic practice.

Quality of cellular attachment to various root-end filling materials

Objectives

This study investigated cellular attachment to 6 root-end filling materials as a measure of the biocompatibility of the materials.

Material and Methods

Class I retrograde cavities were prepared in root slices and these cavities were filled with the test materials, and incubated with Balb/C 3T3 fibroblasts for 24 h. Root slices with the cavities left empty served as the controls. The root slices were then processed for scanning electron microscopy, and were viewed to assess the quality of cellular attachment by observing the shape of cells, spread, and membrane outline.

Results

The best cellular attachment was observed at MTA and Geristore surfaces: cells exhibited characteristic elongated fibroblastic morphology, with projections of lamellipodia, filopodia, blebs, and microvilli from their surfaces, reflecting good attachment to the material. Fibroblasts attached poorly to the surfaces of IRM, Super EBA, KetacFil and Retroplast. Furthermore, the cells did not attach well to the tooth structure next to IRM and Super EBA.

Conclusions

The present study demonstrated a variation in cellular attachment to different root-end filling materials with the best cellular attachment to the surfaces of MTA and Geristore. IRM and Super EBA, Ketac Fil and Retroplast rendered poor attachment.

Toxicity testing of restorative dental materials using brine shrimp larvae (Artemia salina)

This study investigated the effect of extracts of different composites, glass ionomer cement (GIC)s and compomers on the viability of brine shrimp larvae. Ethanolic extracts of four dental composites (Z-100; Solitaire 2; Filtek P60 and Synergy), a conventional GIC (Ketac-Fil), a resin-modified glass ionomer cement (Vitremer), two compomers (F2000; Dyract AP), and a flowable compomer (Dyract Flow) were prepared from each material. Following evaporation of the ethanol, the extracts were resuspended in distilled water, which was then used to test the effects on the viability of brine shrimp larvae. For the composites, the extract of Synergy was the least toxic (88% viability) followed by the extracts of Solitaire 2, Z100 and P60 (75%, 67.5% and 50% viability, respectively). One-way ANOVA revealed highly significant differences between the resin composite materials (p<0.001). Follow-up comparison between the composite groups by Tukey's pairwise multiple-comparison test (α =0.05) showed that the extract of Synergy was significantly less toxic than the extracts of all the other materials except that of Solitaire 2. The compomers showed 100% lethality, while the percentage of viable larvae for the extracts of Ketac-Fil, and Vitremer were 32.3%, and 37.0%, respectively. One-way ANOVA revealed highly significant differences between the groups of materials (p<0.001). Follow-up comparison between the groups by Tukey's test (α = 0.05) showed that the toxic effect of the extracts of the compomers were significantly greater than that of Ketac-Fil, and Vitremer. The differences in the toxic effects of Vitremer and Ketac-Fil were not statistically significant. In conclusion, the toxicity of composite materials varied according to their chemical composition. Compomers were the most lethal materials to brine shrimp larvae followed by GICs and then composites.

Cytotoxicity of dental composites and their leached components

OBJECTIVES

To investigate the toxicity of 4 types of resin-based dental composites with different compositions and to determine the components released from them using high-performance liquid chromatography (HPLC).

METHOD AND MATERIALS

Resin composite disks (Z100, Solitaire 2, Filtek P60, and Synergy) were prepared, and cytotoxicity was tested on Balb/C 3T3 fibroblasts. In the first part of the study, cells were exposed to the composites for 72 hours (direct method), and in the second part to ethanolic extracts of the composites for 24 hours (indirect method), both at 37 degrees C. Cell viability was then determined by the MTT (3[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) method.

RESULTS

The dental composites and their ethanolic extracts had adverse effects on the viability of Balb/C 3T3 fibroblasts. ANOVA revealed highly significant differences in cytotoxicity between the groups (P <.001) for both the direct and indirect methods. Follow-up comparison by Tukey test (alpha = .05) showed that Synergy was significantly less toxic than the other resin composites and Solitaire 2 was significantly more cytotoxic when the materials were tested by the direct method. However, using the indirect method, the extract of Synergy was significantly more toxic than all the other extracts. Bis-GMA, TEGDMA, UDMA, bis-EMA, and bisphenol A were detected by HPLC analysis; however, their presence and concentrations varied from one composite to another.

CONCLUSIONS

The cytotoxicity level of resin-based dental composites depends on their chemical composition, leaching medium, and the amount and type of the components that can be extracted from the materials.

The presence of Pseudomonas aeruginosa in the dental unit waterline systems of teaching clinics

OBJECTIVE

The objective of this study was to evaluate the extent of Pseudomonas aeruginosa contamination of Dental Unit Water (DUW) at a Dental Teaching Center in Jordan.

METHODS

Water samples were collected from 30 dental units, 10 from each of three teaching clinics, namely conservative dentistry, periodontology, and prosthodontics. Samples were collected from the outlet of the air/water syringe, high-speed handpiece and water cup filler, at the beginning of the working day (before use), after 2 min flushing, and at midday.

RESULTS

P. aeruginosa was detected in 86.7% (26/30) of the dental units at the beginning of the working day, and in 73.3% (22/30) after 2 min of flushing and at midday. Conservative dentistry units had the highest counts, followed by periodontology and prosthodontics (P<0.05). Overall, the highest counts (log10 count CFU ml-1) were at the beginning of the working day (1.38+/-1.05), and the lowest counts after flushing for 2 min (1.10+/-1.03), and higher numbers were seen again at midday (1.15+/-1.04) (P<0.05).

CONCLUSIONS

86.7% of the dental units were contaminated with P. aeruginosa, the conservative dentistry units had the highest amount of contamination. Flushing the DUW for 2 min significantly reduced the counts of P. aeruginosa.

The radiographic outcomes of direct pulp-capping procedures performed by dental students: a retrospective study

BACKGROUND

The decision between pulp capping and root canal therapy after pulp exposure is a clinical issue. The aim of the authors' study was to evaluate the outcome of direct pulp-capping procedures performed by dental students.

METHODS

The authors followed the treatment outcomes of 193 patients with 204 pulp exposures with direct pulp capping. They determined the outcome of pulp capping radiographically using periapical radiographs taken at least three years after pulp exposure. The outcome was considered as successful if the tooth was present and not associated with periapical radiolucency or root canal treatment; otherwise, the outcome was considered as being a failure.

RESULTS

Overall, the success rate of pulp capping was 59.3 percent. The success was associated more with mechanical exposure than with carious exposure (92.2 versus 33.3 percent) (P < .001), more with permanent restoration than with temporary restoration (80.8 versus 47.3 percent) (P < .001) and more with class I occlusal restoration (83.8 percent) than with proximal multiple surface restorations (Class II, 56.1 percent; Class III, 58.8 percent; mesial-occlusal-distal, 28.6 percent) (P = .009). Patients' age, sex, and tooth location and position had no significant effect on the outcome (P > .05).

CONCLUSION

The success rate of direct pulp capping was 92.2 percent with mechanical exposure and 33.3 percent with carious exposure.

CLINICAL IMPLICATIONS

Direct pulp capping is recommended after mechanical exposure with immediate placement of permanent restoration, while root canal therapy would be the choice of treatment if the exposure was due to caries.

In vivo effects of BISGMA-a component of dental composite-on male mouse reproduction and fertility

The aim of this study is to investigate the effects of the resin monomer bisphenol A glycerolate dimethacrylate (BISGMA) on adult male mouse fertility. Male Swiss mice were administered various concentrations of BISGMA (0, 25, and 100 microg/kg) for a period of 28 days, and the effects on fertility was assessed by breeding these males with untreated female mice after the exposure periods. The results showed that fertility was significantly reduced when male mice were exposed to BISGMA, in comparison with their control counterparts. In females mated with males exposed to BISGMA, there was a significant reduction in the pregnancy rates as well as the number of viable fetuses. The number of resorptions out of the total number of implantations was significantly increased in females mated with males that had been exposed to BISGMA. Furthermore, the number of females with resorptions was also significantly increased. Significant reductions in bodyweight and weights of the testis and preputial glands were also observed. The weights of the seminal vesicles were significantly increased in males exposed to BISGMA in comparison with their control counterparts. There were significant reductions in testicular sperm counts, epididymal sperm counts and in the efficiency of sperm production. In conclusion, exposure of male mice to BISGMA results in an impairment of the reproductive system and fertility.

Tooth wear among psychiatric patients: prevalence, distribution, and associated factors

PURPOSE

The purpose of this study was to evaluate the prevalence, distribution, and associated factors of tooth wear among psychiatric patients.

MATERIALS AND METHODS

Tooth wear was evaluated using the tooth wear index with scores ranging from 0 to 4. The presence of predisposing factors was recorded in 143 psychiatric patients attending the outpatient clinic at the Prince Rashed Hospital in northern Jordan.

RESULTS

The prevalence of a tooth wear score of 3 in at least one tooth was 90.9%. Patients in the age group 16 to 25 had the lowest prevalence (78.6%) of tooth wear. Increasing age was found to be a significant risk factor for the prevalence of tooth wear (P < .005). The occlusal/incisal surfaces were the most affected by wear, with mandibular teeth being more affected than maxillary teeth, followed by the palatal surface of the maxillary anterior teeth and then the buccal/labial surface of the mandibular teeth. The factors found to be associated with tooth wear were age, retirement and unemployment, masseter muscle pain, depression, and anxiety.

CONCLUSION

Patients' psychiatric condition and prescribed medication may be considered factors that influence tooth wear.

Effects of extracts of miswak and derum on proliferation of Balb/C 3T3 fibroblasts and viability of cariogenic bacteria

OBJECTIVES

This study examined the effects of extracts of two chewing sticks on proliferation of fibroblasts and viability of cariogenic bacteria.

METHODS

Aqueous extracts of miswak (Salvadora persica; Arak tree) and derum (Juglans regia; walnut tree) were prepared and their effects investigated on growth of Balb/C 3T3 mouse fibroblasts by measuring the mitochondrial succinic dehydrogenase activity. Furthermore, the effects on the viability of various cariogenic bacteria (Streptococcus mutans, Streptococcus salivarius, Lactobacillus casei and Actinomyces viscosus) was also determined.

RESULTS

The data revealed that Balb/C 3T3 fibroblasts exposed to aqueous extracts of miswak or derum showed an increase in cell proliferation by 156% and 255%, respectively, in comparison with controls (p < 0.0001). Furthermore, extracts from both miswak and derum had adverse effects on the growth of the cariogenic microorganisms, with derum having significantly greater antimicrobial effects than miswak and at much lower concentrations against all the bacteria tested. The most sensitive organisms were A. viscosus, followed by S. mutans, S. salivarius, with L. casei being the most resistant.

CONCLUSION

The results show that aqueous extracts of miswak and derum enhance the growth of fibroblasts and inhibit the growth of cariogenic bacteria, with the derum extract showing greater activity than miswak.

The effects of BIS-GMA and TEG-DMA on female mouse fertility

OBJECTIVES

The current study evaluated the effect of bisphenol A glycerolate dimethacrylate (BIS-GMA) and triethyleneglycol dimethacrylate (TEG-DMA) on female mouse fertility.

METHODS

Adult female mice were exposed to BIS-GMA or TEG-DMA (0, 25 and 100 microg/kg) intragastrically daily for 28 d and then mated with sexually mature untreated male mice and after mating their fertility was assessed.

RESULTS

In females exposed to BIS-GMA at both doses significant increases in the total number of resorptions out of the total number of implantations were observed, with a significant increase in the number of animals with resorptions at the higher dose. Significant reductions in body weights and significant increases in ovary weights were also observed. Exposure to TEG-DMA at a dose of 100 microg/kg resulted in significant reductions in pregnancy rates and a significant increase in the total number of embryonal resorptions. Significant reductions in body and uterine weights were also observed in females exposed to TEG-DMA.

SIGNIFICANCE

The results suggest that both BIS-GMA and TEG-DMA have reproductive toxic effects in female mice.

The effects of recasting on the cytotoxicity of base metal alloys

STATEMENT OF PROBLEM

Cytotoxicity of cast alloys depends on their composition and element release, which may be affected by recasting of the alloy.

PURPOSE

This study investigated the effect of recasting on the element release and cytotoxicity of 5 base metal alloys.

MATERIAL AND METHODS

The alloys tested consisted of: 2 Ni-Cr (Remanium CS and Wiron 99); a Ni-Cr with Cu (CB Soft); a Co-Cr (Wirobond C); and a Cu-base (Thermobond). Alloy specimens (disks 3 x 5 mm) were cast as follows: 100% new alloy; 50% new with 50% recast; and 100% recast (n = 6). Cytotoxicity was tested using Balb/C 3T3 fibroblasts and the MTT assay. Six replicates were tested for each alloy, and the controls consisted of 6 wells containing cells with no alloy specimens. The release of elements from the alloys into culture medium was also investigated. The data were analyzed by 2-way analysis of variance (ANOVA) followed by the Tukey Honestly Significant Difference test (family error rate =.05).

RESULTS

At all 3 variations of casting, Remanium CS and Wiron 99 were the least cytotoxic, followed by Wirobond C, CB Soft, and Thermobond. ANOVA revealed significant differences between the groups (P <.001). Post hoc analysis showed that overall, Thermobond was significantly more cytotoxic than all of the other alloys tested (P <.05). For the 100% new alloy groups the cytotoxicity of Co-Cr alloy Wirobond C was similar to that of the Ni-Cr alloys Remanium CS and Wiron 99; however, when the alloys were recast, Wirobond C became significantly more cytotoxic and as toxic as the Ni-Cr alloy containing Cu (CB Soft). Moreover, recasting significantly increased the cytotoxicity of all the alloys (P <.05) and the amounts of elements released from them.

CONCLUSION

The Cu content in an alloy increased its cytotoxicity level remarkably. Recasting of alloys significantly increased their cytotoxicity level. The Co-Cr alloy was more adversely affected by the recasting than the Ni-Cr alloys.

Cytotoxicity evaluation of dental resin composites and their flowable derivatives

The release of components from dental composite into surrounding tissue may cause an adverse tissue reaction. Thus, this study investigated the cytotoxicity of three types of dental composites with their flowable derivatives and determined the compounds released from these materials by high-performance liquid chromatography (HPLC) analysis. Fifteen specimens from each composite (Admira, Z250, Tetric Ceram) with fifteen of their flowables (Admira Flow, Tetric Flow, Feltik Flow) were prepared in the form of discs and divided into two groups of 10 and 5 for each material. The first group (10 discs) was used to evaluate the cytotoxicity of the material on balb/c 3T3 fibroblasts by measuring cellular metabolic activity (3{4,5-dimethylthiazol-2-yl}-2,5-diphenyltetrazolium bromide [MTT] assay) relative to Teflon controls, while the second group (5 discs) was used to determine the leached components from each material into culture medium by HPLC analysis. The results revealed that Z250 and Tetric Ceram were less cytotoxic than their flowable derivatives. However, the ormocer, Admira, was significantly more cytotoxic than Admira Flow. Among the standard composites, Tetric Ceram was the least cytotoxic and Admira the most. Furthermore, Tetric flow was the most cytotoxic and Admira flow was significantly the least cytotoxic among the flowable materials tested. HPLC analysis revealed bisphenol A glycerolate dimethacrylate (bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) in the eluates of all the materials, while urethane dimethacrylate (UDMA) was present in all eluates except that of Feltik Flow. In conclusion, the flowable derivatives are more cytotoxic than the traditional composites whereas the ormocer Admira Flow is less cytotoxic than the Admira composite.

The resin monomer triethylene glycol dimethacrylate exhibits reproductive toxicity in male mice

The present study evaluated the effect of triethyleneglycol dimethacrylate (TEGDMA) on mouse fertility. Adult male mice were administered TEGDMA (0, 25 and 100 μg kg–1) intragastrically daily for 28 days and then allowed to mate for 10 days with sexually mature untreated female mice; fertility was assessed after a further 10 days. Females mated by males that had been treated with TEGDMA had a significant reduction in pregnancy rate, as well as a significant increase in the total number of resorptions as a percentage of the total number of implantations. Furthermore, the number of animals in which resorption occcurred was increased significantly. Males treated with TEGDMA exhibited a significant reduction in bodyweight, testis weight and the weight of the seminal vesicles and preputial glands. Testicular and epididymal sperm counts, as well as the efficiency of sperm production, were also significantly reduced in TEGDMA-treated males. The results suggest that TEGDMA has adverse effects on the fertility and reproductive system of male mice.

Reproductive toxic effect of bisphenol A dimethacrylate in mice

The current study evaluated the effect of bisphenol A dimethacrylate (Bis-DMA) on mouse fertility. Adult male and female mice were exposed to intragastric Bis-DMA (0, 5, 25, and 100 microg/kg) daily for 28 days and then mated with sexually mature untreated mice and after mating fertility was assessed. Females mated by males that had been exposed to Bis-DMA had significant reductions in pregnancy rates and significant increases in the total number of resorptions out of the total number of implantations. Bis-DMA exposed males had significant reductions in body weights and relative testes weights and significant increases in seminal vesicle and preputial gland weights. Testicular and epididymal sperm counts as well as the efficiency of sperm production were also significantly reduced in these groups. Female mice exposed to Bis-DMA showed significant reductions in pregnancy rates, number of implantation sites, number of viable fetuses, and total number of resorptions out of the total number of implantations. Significant reductions in the body weights were observed at all doses, and significant increases were found in the relative weights of the ovaries and the uterus. The results suggest that Bis-DMA has adverse effects on the fertility and reproductive systems of male and female mice.

Leached components from dental composites and their effects on fertility of female mice

This study investigated the effects of leached components from a resin-based dental composite (Z-100) and bisphenol A (BPA) on female mouse fertility. Leached components or BPA (5, 25 and 100 microg kg(-1)) were administered intragastrically daily to the test and distilled water to the control groups for 28 d. Female mice were then mated with sexually mature untreated males and their fertility was assessed. The results revealed a significant reduction in the number of pregnancies--54.5% vs. 100% (control)--in mice treated with the leached components from the dental composite, which also showed an increase of 142% in relative ovary weights. Exposure to 25 and 100 microg kg(-1) BPA resulted in significant increases in the total number of resorptions out of the total number of implantations and significant increases in relative uterine weights. Relative ovarian weights were significantly increased at the highest dose. High performance liquid chromatography analysis showed that tri-(ethylene glycol)-dimethacrylate (TEG-DMA) was the major leached component (total: 5945 microg ml(-1)) from the composite, followed by bisphenol A glycerolate dimethacrylate (BIS-GMA) (total: 2097 microg ml(-1)) and BPA (total: 78 microg ml(-1)). The results suggest that leached components from the dental composite used and commercially purchased BPA have adverse effects on the fertility and reproductive system of female mice.

The relationship between static and dynamic occlusion in 14-17-year-old school children

This study investigated the relationship between static and dynamic occlusion in school children. A total of 447 subjects, within an age range of 14-17 years with no history of orthodontic treatment or trauma to the teeth were included in this study. Static occlusion was determined for both incisal and molar relationship. Dynamic occlusion was determined in lateral and protrusive movements of the mandible. The majority of the subjects had class I static occlusion for both incisor and molar relationship (45 and 54%, respectively). Canine-guided occlusion was the dominant type of dynamic occlusion (57%) and most of the subjects had no posterior contact in protrusive movement (78%). There was an association between canine guidance with class II static occlusion. Statistically, a significant relationship was found between the dynamic and static occlusion of the incisor (P < 0.001) but not with the molar (P > 0.05).

Radiographic technical quality of root canal treatment performed by dental students at the Dental Teaching Center in Jordan

OBJECTIVES

The objective of this study was to evaluate radiographically the technical standard of root canal treatment performed by undergraduate dental students at the Dental Teaching Center in Jordan.

METHODS

A random sample of 8500 records of dental patients was examined. A total of 542 endodontically treated teeth with 912 roots were evaluated. Periapical radiographs were used to assess the technical quality of the root canal filling. The length of each root canal filling was categorized as acceptable, short and overfilled based on their relationship with the radiographic apex. Density and taper of filling was evaluated based on the presence of voids and the uniform tapering of the filling, respectively. Chi-square analysis was used to determine statistically significant differences between adequacy of root canal filling in each group of teeth according to its location, position and curvature.

RESULTS

Sixty-one percent of roots had fillings of acceptable length, while 34.5% were short and 4.2% were overfilled. The root canal fillings of 47.4% were found to be adequate. Adequate fillings were found more in maxillary than mandibular teeth (P < 0.005), anterior compared to posterior teeth (P < 0.05) and in straight canals compared to curved canals (P < 0.001).

CONCLUSION

The technical quality of root canal treatment performed by undergraduate dental students using step-back preparation and lateral condensation was found to be less than 50%. Review of the endodontic curriculum requirements, specialized clinical supervision and increasing the time of training at the preclinical and clinical levels should improve this quality.

Cytotoxicity of dental casting alloys after conditioning in distilled water

PURPOSE

This study investigated the cytotoxicity of various types of dental casting alloys after they had been conditioned in distilled water.

MATERIALS AND METHODS

The casting alloys investigated included one high-noble alloy (Bioherador N) and six base-metal alloys, including four Ni-Cr alloys (Remanium CS, Heranium NA, Wiron 99, CB Soft), one Co-Cr alloy (Wirobond C), and one Cu-based alloy (Thermobond). Ten disks from each alloy were conditioned in distilled water at 37 degrees C for either 72 or 168 hours. The cytotoxicity of the alloys was then tested on Balb/C 3T3 fibroblasts, which were exposed to the alloys for 3 days at 37 degrees C. Cell viability was determined by the MTT method. The data were analyzed by ANOVA, and follow-up comparison between the groups was carried out using Tukey and t tests.

RESULTS

ANOVA revealed a significant effect of alloy type and conditioning time (P < .001). Bioherador N was significantly less toxic than all the other alloys in the 72-hour conditioned group. After 168 hours of conditioning, its cytotoxicity was not different (P > .05) from that of Remanium CS, Wiron 99, and Wirobond C. Thermobond and CB Soft were significantly more toxic than the other alloys at both conditioning times.

CONCLUSION

Conditioning of base-metal alloys, other than those containing Cu, for 168 hours in distilled water makes their cytotoxicity levels comparable to that of the high-noble alloy.

An investigation of the cytotoxic effects of dental casting alloys

PURPOSE

This study investigated the cytotoxicity of a high-noble alloy (Bioherador N) and six commercially available base-metal alloys, including four Ni-Cr alloys (Remanium CS, Heranium NA, Wiron 99, CB Soft), one Co-Cr alloy (Wirobond C), and one Cu-based alloy (Thermobond).

MATERIALS AND METHODS

Ten specimens from each alloy were prepared in the form of disks, which were placed in 24-well tissue culture plates together with a suspension containing Balb/C 3T3 fibroblasts (5 x 10(5) cells/mL). After 3 days of incubation at 37 degrees C, cell viability was determined by the MTT method.

RESULTS

Variations in cytotoxicity of the alloys were observed and related to their composition. One-way ANOVA showed statistically significant differences in cytotoxicity of the alloys (P < .001). Tukey's multiple comparisons (alpha = .05) revealed that Bioherador N was significantly less cytotoxic than all the other alloys. Thermobond was the most cytotoxic, followed by CB Soft, and both of these alloys were significantly more cytotoxic than all the others.

CONCLUSION

The cytotoxicity of casting alloys tested in this study was markedly affected by their composition. Differences were found in the cytotoxicity of alloys classified within the same category. The presence of Cu in the composition of the alloy adversely affected cell viability.

The effect of an extract of Salvadora persica (Meswak, chewing stick) on fertility of male and female mice

This study investigated the toxic effects of an extract of Meswak from Salvadora persica for 30 days on the reproductive system of the mouse. The results showed that exposure to Meswak extract did not have much effect on female mouse fertility, although it caused a significant decrease in the relative weights of the ovary and an increase in uterine weights. Exposure of male mice to Meswak extract resulted in a 72% reduction in pregnancies in untreated females impregnated by test males. The relative weights of the testes and preputial glands were significantly increased and that of the seminal vesicles was significantly decreased in test males. The results indicate that Meswak has adverse effects on male and female reproductive system and fertility.

Effects of bisphenol A on adult male mouse fertility

The aim of this investigation was to evaluate the effect of bisphenol A (BPA), a contaminant of resin-based dental composites and sealants, on the fertility of male mice. Forty adult male Swiss mice were divided into four groups of 10. BPA (5, 25 and 100 micro g kg(-1) [corrected] was administered intragastrically daily to the mice in the test groups and distilled water to the control group for 28 d. Male fertility was assessed by mating each mouse with two untreated females. Females mated with male mice having ingested 25 and 100 micro g kg(-1) [corrected] BPA showed a significant reduction in pregnancy rates. Furthermore, the total number of resorptions out of the total number of implantations was significantly increased in females impregnated with males having ingested all three doses of BPA. Males having ingested 25 and 100 micro g kg(-1) [corrected] BPA showed a significant reduction in testicular sperm counts and in the efficiency of sperm production. Epididymal sperm counts were also significantly reduced in males that had ingested BPA. There were significant reductions in the absolute weights of the testes and seminal vesicles. These results suggest that male fertility and reproduction is impaired by bisphenol A.

Effects of resin based dental composites on fertility of male mice

The purpose of this study was to investigate the effect of leached substances from dental composites on the fertility of male mice. Twenty adult male Swiss mice were divided into two groups of 10. Leached substances from composite specimens were administered, intragastrically, daily to the mice in the test group and distilled water to the control group for 28 d. Each mouse from both groups was mated with two untreated females. After mating, fertility of male mice in both groups was assessed. There was a significant reduction in the number of pregnancies in females mated with test males in comparison to those mated with control males (12/20 vs. 18/20, respectively). Females impregnated by test male mice showed a significant increase in the number of resorptions out of the total number of implantations (11% test vs. 1.5% control). The testicular sperm count and daily sperm production of the males in the test group was significantly reduced. Moreover, the relative weights of the testes and seminal vesicles were also significantly reduced in the test group. These results suggest that leached components from resin based dental composite materials have an adverse effect on the fertility and reproductive system of male mice.