Journal of Dental Medicine

Background and Aim: The aim of this investigation was to evaluate the osteopromotion property of homogenous demineralized dentin matrix (HDDM) on experimental surgical bone defects in parietal bone of rabbits using the guided bone regeneration (G.B.R.) technique incorporating Paroguide collagen membrane.

Materials and Methods: Surgical bone defects were created in 6 Newzland white rabbits (2 defects in each rabbit). The defects were protected by Paroguide membrane alone (control group) or filled with HDDM and protected by Paroguide membrane (experimental group). The HDDM had been obtained from the central incisors of rabbits. The rabbits were sacrificed after 15, 30, 45, 60, 75 and 90 days and the defects examined histologically. Data were analyzed using pair-t test. The level of significance was set at p=0.03.

Results: Histologically, the volume of newly formed bone matrix was significantly greater in the experimental group. No inflammatory reaction was seen in either experimental or control groups.

Conclusion: Bone regeneration was accelerated in the bone defects filled with HDDM in comparison to the control group.

Background and Aim: It is well recognized that implant treatment is common worldwide, but the approach to success is not predictable because of bone loss that occurs around the implants. Also there are many factors affecting crestal bone loss around the implants that one of them is the surgical protocol of implant installation. The purpose of this investigation was to evaluate the amount of crestal bone loss around the Replace implants installed according to submerged and non- submerged treatment protocol.

Materials and Methods: In this study, 11 patients received 34 implants. In each patient (unilateral or bilateral mandible), one of the implants was placed with submerged procedure and in the other one non- submerged procedure was used. In a period of 3 months a temporary partial denture that covered the implants was used. After 3 months the submerged fixture was exposed, impression was performed and fixed prosthesis was fabricated. Loss of crestal bone at each implant was measured. These measurements have been done at surgical times, over a period of 3 months after implant installation and 6 months after the delivery of the fixed prosthesis. The measurement was done with digital subtraction radiography. Data was analyzed by Wilcoxon Signed Ranks test.

Results: Three months after implant placement, submerged groups showed statistically more crestal bone loss (0.65±0.71) than non-submerged (0.41±0.53) group (p=0.02). After 6 months the mean value of crestal bone loss in submerged group was 0.21±0.40 mm and in non submerged group was 0.29±0.49 mm. This data indicated no statistically significant difference between the two groups of implants (p>0.05).

Conclusion: Our results are in accordance with previously published studies and confirm that the value of crestal bone loss in submerged and non-submerged groups after 3 and 6 months were similar and in acceptable limit.

Background and Aim: The aim of this clinical study was to determine the effectiveness of progressive loading procedures on preserving crestal bone height and improving peri-implant bone density around maxillary implants restored with single crowns by an accurate longitudinal radiographic assessment technique.

Materials and Methods: Eleven Micro-Thread Osseo Speed dental implants were placed in 11 subjects and permitted to heal for 6 weeks before surgical uncovering. Following an 8-week healing period, implants underwent a progressive loading protocol by increasing the height of the occlusal table in increments from adding acrylic resin to an acrylic crown. The progressively loaded crowns were placed in 2 mm infraocclusion for the first 2 months, light occlusion for the second 2 months, and full occlusion for the third 2 months. At forth 2 months, a metal ceramic crown replaced the acrylic crown. Digital radiographs of each implant were made at the time of restoration, then after 2, 4, 6, 8, and 12 months of function. Digital image analysis was done to measure changes in crestal bone height and peri-implant bone density.

Results: The mean values of crestal bone loss at 12 months were 0.11 ± 0.19 mm, and when tested with Friedman across the time periods, the differences were not statistically significant (p> 0.05). The mean values of bone density in the crestal, middle, and apical area were tested with Repeated Measure ANOVA across the time periods, the differences were statistically significant (p<0.05).

Conclusion: Progressive loading doesn’t cause crestal bone loss. The peri-implant density measurements of the progressively loaded implants show continuous increase in crestal, middle and apical peri-implant bone density by time.

Background and Aims: Considering advantages and disadvantages of mineral trioxide aggregate (MTA), Calcium Enriched Mixture (CEM) cement has been developed recently. The purpose of this study was to compare the apical microleakage of the root-end cavities prepared by ultrasonic or Er,Cr:YSGG laser and filled with MTA or CEM cement.

Materials and Methods: Eighty single-rooted, extracted human teeth were instrumented and obturated. Root-end resection was made by removing 3 mm of the apex. The teeth were randomly divided into two experimental (n=30) and two positive and negative control (n=10) groups. After that, the retrograde cavities were prepared using ultrasonic or Er,Cr: YSGG Laser. According to the root-end filling materials (MTA or CEM cement), each group was then divided into two subgroups. Finally, specimens were cleared for assessing the amount of apical dye (Indian ink) penetration. The data were analyzed using Kruskall-Wallis and Dunn tests.

Results: Laser/CEM cement group showed significantly the lowest mean apical dye penetration. There were no statistically significant differences between Laser/MTA, ultrasonic/MTA and ultrasonic/CEM cement groups.

Conclusion: Based on the findings of this study, CEM cement demonstrated lower rate of apical leakage compared with MTA, when the root-end cavities prepared with Er,Cr:YSGG Laser. The sealing ability of MTA was not different following root-end preparation by ultrasonic or Er,Cr:YSGG Laser.

A procedure was explained to fabricate a surgical stent to aid the placement of maxillofacial implants for prosthetic auricular rehabilitation. An impression of the defect was made, and a wax pattern of the missing ear completed and evaluated on the patient. The definitive wax prosthesis was processed in clear acrylic resin. Also an occlusal maxillary splint was fabricated and joined to the acrylic resin ear by using an extraoral acrylic resin bar. Surgical stent provides proper orientation of the acrylic resin ear while remaining attached to the maxillary arch. This surgical stent can also be used for radiographic examination.

Background and Aims: One of the common human evolutionary anomalies is dental Missing. Evolution of dental system is toward deduction of teeth number. The Missing of third molar is interesting subject for dentists and genetic researches because of its variety in different races. Consideration of bilateral effect of third molar Missing with jaw relation is an important subject. The aim of this study was to evaluate the third molar missing in Cl I and Cl II skeletal (without rotation) and comparison of them together.

Materials and Methods: The patients of the orthodontic department of school of Dentistry (Tehran University of Medical Sciences) were analyzed. About 121 patients had Cl I and 60 patients had ClI jaw relation. This relation identified based on cephalometric lateral radiographic ANB corner angle. Patient who had rotation in maxilla or mandible based on SN-Go Gn angle were excluded. The incidence of third molars agenesis in individual dentition quadrants, upper and lower jaw and right and left side of dentition was examined from panoramic radiography. AChi-square test was used for statistical analysis of data.

Results: Missing of one or more third molar in skeletal Cl I and Cl II was 43% and 33.3%, respectively. Missing of one or more third molar in Cl II was fewer than Cl I, but no statistically significant differences were seen between them.

Conclusion: There was not a direct relationship between jaw relation and third molar Missing.

Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movements and to inhibit the pain during tooth movements. Considering the contradictory finding in this respect, the effect of low level laser therapy (LLLT) was evaluated on the pain during orthodontic tooth movement.

Materials and Methods: In this randomized clinical trial study, 12 patients were included with extracted upper first premolars and required canine retraction into extraction site. While in both sides canines were retracted by Niti coil spring, one side was exposed to GaAlAs laser (890nm). LLLT was done on the buccal and palatal mucosa by slow movement of probe. The patients were asked about their pain on both sides 2 days after beginning of retraction. Pain measurement was evaluated with VAS.

Results: Pain perception in LLLT side significantly decreased (P=0.007).

Conclusion: Based on the results, single irradiation of GaAlAs laser (12J energy per tooth) can decrease pain perception.

Background and Aims: The main purpose of orthodontic treatment is normal positioning of teeth in three dimensional plans, including the mesiodistal inclination. In this study, mesiodistal axial inclination of posterior teeth in skeletal class II was evaluated and compared with that of posterior teeth in skeletal class I.

Materials and Methods: Seventy-eight panoramic radiographs for subjects between 12 to 24 years old with skeletal class I and 78 panoramic radiographs for subjects between 12 to 19 years old with skeletal class II were selected. All of the subjects were in permanent dentition with no tooth missing, no tooth extraction, no impacted tooth, and no crowding in posterior teeth. Two reference lines were established over each radiograph: the upper one passing through the most inferior point of right and left orbits lower one passing through the right and left mental foramina. After that, the long axis of teeth was traced (the image of root canal in single-rooted teeth, mean image of buccal and palatal canals in upper premolars, mean image of mesial and distal canals in lower molars, and the image of palatal canal in upper molars.). The mean values for two skelotodental classes were analyzed using T-test.

Results: The results showed that there was significant difference between (P<0.05) mesiodistal axial inclination of teeth 15, 16, 17, 25, 26, and 27 in upper jaw in skeletal class II compared with that of the same teeth in skeletal class I, which was more mesially in skeletal class II. Mesiodistal axial inclination of teeth 36, 46, and 47 in lower jaw was more mesially in class II compared with that of the same teeth in class I. For other teeth there were no significant differences between two skeletodental classes (P>0.05).

Conclusion: The mesiodistal axial inclination of upper molars and second premolars and lower molars in class II was more mesially compared with that of the same teeth in class I.

Background and Aims: Selecting an appropriate treatment plan is one of the most critical aspects of dental treatments. The purpose of this study was to compare multimedia system and conventional method in patients' selecting prosthetic treatment and the time consumed.
Materials and Methods: Ninety patients were randomly divided into three groups. Patients in group A, once were instructed using the conventional method of dental office and once multimedia system and time was measured in seconds from the beginning of the instruction till the patient had came to decision. The patients were asked about the satisfaction of the method used for them. In group B, patients were only instructed using the conventional method, whereas they were only exposed to soft ware in group C. The data were analyzed with Paired-T-test (in group A) and T-test and Mann-Whitney test (in groups B and C).
Result: There was a significant difference between multimedia system and conventional method in group A and also between groups B and C (P<0.001). In group A and between groups B and C, patient's satisfaction about multimedia system was better. However, in comparison between groups B and C, multimedia system did not have a significant effect in treatment selection score (P=0.08).
Conclusion: Using multimedia system is recommended due to its high ability in giving answers to a large number of patient's questions as well as in terms of marketing.

Background and Aims: Marginal adaptation is important for the long-term success of full-coverage restorations. Preparation design is one of the important factors influencing the marginal integrity. Therefore, the purpose of this study was to compare the effect of radial shoulder and chamfer finish line designs on the marginal adaptation of all-ceramic Cercon restorations.
Materials and Methods: This in vitro study was done using single blind experimental technique. One stainless steel die with 7 mm height and 5 mm diameter was prepared by milling machine. The preparation design consisted of half radial shoulder with 1mm depth and half chamfer with 0.8mm depth. All walls had a convergence angle of 10º. Ten stone dies and ten ZrO2 copings of Cercon (Cercon Smart Ceramics, DeguDent, Hanau, Germany) were made and after cementation were ground at buccolingual direction. Then marginal gap of each sample was measured by scanning electron microscopy. Data were then analyzed using t-test.
Result: The mean marginal gap for radial shoulder was 98.4µ and for chamfer was 39.7µ. The difference was statistically significant (P=0.002).
Conclusion: The marginal gap of chamfer preparation is less than that of radial shoulder.

Background and Aims: Cephalometric measurements cannot be performed for screening purposes, therefore orthodontists usually have to use either photographic or anthropometric measurements in such occasions. Finding a valid and reliable alternative could be of great value. The purpose of this study was to evaluate the correlation between McNamara's cephalometric unit difference and a proposed soft tissue equivalent.
Materials and Methods: An anthropometric ruler was redesigned and used in this study. Soft tissue measurements were performed on 36 randomly selected specimens by two investigators. The soft tissue measurements included external auditory meatus to subnasale (Ext-Sn), external auditory meatus to soft tissue pogonion (Ext-Pog), and the difference between them (UDMA´). These measurements were considered as equivalents to cephalometric indices in McNamara's anteroposterior measurements, including maxillary (Co-A) and mandibular (Co-Gn) unit length and their difference (UDMA), respectively.
Results: All soft tissue variables had an intra-class correlation coefficient (ICC) above 0.90. There was a high and significant correlation between cephalometric and anthropometric measurements (P<0.01). The ICC between (Ext-Sn) and (Co-A) was 0.890, 0.869 between (Ext-Pog) and (Co-Gn), and 0.819 between UDMA´ and UDMA.
Conclusion: The proposed anthropometric method showed a good correlation with cephalometric equivalents and the results show that this method could be used for screening purposes, especially when a low-cost, non-invasive method is required. However it cannot be considered as a substitute for cephalometry in diagnostic and treatment purposes.

Background and Aims: Nowadays, calcium hydroxide is used as a dressing for canal sterilization and repair progression of apical lesions. The aim of this study was to investigate the effect of calcium hydroxide as an intracanal medicament on the apical microleakage of root filling.
Materials and Methods: In this experimental study, 46 extracted single-rooted human teeth were instrumented with step-back technique to master apical file (MAF) size 35. Specimens were randomly divided into 2 groups (n = 20). In group 1, the specimens were treated with calcium hydroxide intracanal medication and in group 2, the samples did not receive any medication. The teeth were incubated in 100% humidity at 37°C for one week. After that, calcium hydroxide was removed using irrigation with normal saline and reaming with MAF. The root canals were obturated with gutta- percha and AH26 sealer using lateral compaction technique. Specimens were incubated in 100% humility at 37°C for 72 hours and then immersed in India ink for 1 week. Finally, the teeth were cleared and the maximum linear dye penetration was measured under a stereomicroscope at 4X magnification. The data were analyzed by T-test and Chi-square.
Results: There was no significant difference between the two experimental groups (P=0.068).
Conclusion: The findings of this study indicated that using calcium hydroxide as an intracanal medicament did not influence the apical microleakage after final obturation of the root canal system.

Background and Aims: The bond strength between veneer ceramics and zirconia frameworks is the weakest component in the layered ceramics. Due to the possible effect of adding pigments to the core materials on the bond strength between core and veneer as well as the introduction of new ceramic materials in dentistry, the aim of this study was to compare the zirconia core-veneer microtensile bond strength using two ceramic veneers with or without coloring the core.
Materials and Methods: In this experimental study, 12 disc-shaped specimens were fabricated using a manually aided design- manually aided manufactured (MAD/MAM) zirconia core (Zirkonzahn). Two veneering ceramics of Ceram Kiss and Zirkonzahn ICE were also used to veneer the specimens. Half of the Zirkonzahn discs were remained white and the others were colored by shade A2.Then, the discs were cut into microbars (30 for each group) and the microtensile bond strength of the core-veneer was calculated. The specimens were assessed using scanning electron microscopy (SEM) and the data were analyzed using two-way ANOVA and Student's t-test.
Results: Significant differences with respect to veneer layer were found (P<0.001). No significant differences were seen among colored and uncolored cores (P=0.69).
Conclusion: According to the apparent effect of veneering ceramics on the core-veneer bond strength, careful selection of these agents is essential to achieve adequate bond strength between core and veneer to prevent delaminating and chipping failures of zirconia veneered restorations.

Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movement. Considering the contradictory findings in this regard, this study was designed to assess the effect of low level laser therapy (LLLT) on the rate of orthodontic tooth movement.
Materials and Methods: In this randomized clinical trial study, 12 patients (4 boys and 8 girls average age:16.9 ± 3.4) with extracted upper first premolars and required canine retraction into extraction site were included. While in both sides canines were retracted by NiTi coil spring, one side was exposed to GaAlAs laser (890 nm). LLLT was done (on the buccal and palatal mucosa by slow movement of probe) at the beginning of the first month. Impression and cast fabrication performed at the beginning of retraction, one and two months later. The amount of retraction on the cast was measured with the aid of a reference plaque fabricated on the rogae using a digital caliper. Data were analyzed using paired sample T-test and one-sample Kolmogorov-Simirnov test.
Results: There was no significant difference in the amounts of canine movement between laser exposed and control sides (P>0.05).
Conclusion: The energy dose of laser used in this study (72 J per each tooth) was not appropriate for increasing dental movement.

Background and Aims: Instrumentation of the root canals results in formation of smear layer which covers the dentinal tubules. In infected teeth, it is ideal to achieve a material that has the ability to remove the smear layer besides antimicrobial activity. Therefore, this study was designed to evaluate the antimicrobial effect of Citrus aurantifolia extracts (lime juice and rind extract) on Enterococcus faecalis within dentinal tubules in the presence of smear layer.
Materials and Methods: One-hundred and forty dentin tubes were prepared from bovine incisors. After removal the smear layer, the specimens were infected with Enterococcus faecalis. Then, the smear layer was reformed. Test solutions were used as the irrigants in study roups as follows: group 1: 5.25% NaOCl group 2: 17% EDTA group 3: NaOCl+EDTA group 4: Lime juice group 5: ethanolic rind extract of C.aurantifolia group 6: 96% ethanol. Dentin chips were collected from inner and outer layers of dentinal walls and optical density was measured. The data were analyzed using one-way ANOVA and Tamhane tests.
Results: In outer layer of dentin, the efficacy of rind extract was less than that of NaOCl+EDTA (P<0.05). Also Lime juice was less effective than EDTA, NaOCl and NaOCl+EDTA (P<0.05). In inner layer of dentin, Lime juice was significantly less effective than NaOCl and NaOCl+EDTA (P<0.05). The efficacy of rind extract was less than that of NaOCl+EDTA (P<0.05).
Conclusion: In the presence of smear layer, the antimicrobial activity of Lime juice was less than that of NaOCl but the efficacy of rind extract was similar to that of NaOCl.

Background and Aims: Teaching of clinical skills is one of the most important aspects in training medical students. The aim of this study was to compare the effectiveness of videotaped and live demonstrations for applying fissure sealant on permanent molar teeth at Zahedan University of Medical Sciences (2010-2011).

Materials and Methods: Thirty 8th-semester dental students were randomly assigned in two groups (n = 15). In group 1, fissure sealant placement was taught using live demonstration while, in group 2, education was performed by videotaped demonstration. Then, each student applied fissure sealant on the patient's permanent molar tooth. The procedure of fissure sealant placement was assessed and scored by a pedodontist. The students were subsequently asked to rate how helpful the videotape or live demonstration had been. The data were analyzed using T-test and Chi-square test.

Results: The mean students' scores for videotaped and live demonstration were 16.5 and 16.53, respectively. There was no significant difference between the teaching methods according to students' scores (P>0.05). 33% of students rated videotaped demonstration as "good" for its helpfulness and 66% as "very good". However, live demonstration was rated as "good" and "very good" by 66% and 33% of students, respectively. There was no significant difference between two groups (P>0.05).

Conclusion: Both teaching methods were equally effective. Therefore, videotaped demonstration can be used in combination with live demonstration or as an alternative for it.

Background and Aims: Composite restorative materials and dental adhesives are usually cured with light sources. The light direction may influence the bond strength of dental adhesives. The aim of this study was to evaluate the effect of light direction on the microtensile bond strength of fifth and sixth generation dental adhesives.

Materials and Methods: Prime & Bond NT and Clearfil SE bond were used with different light directions. Sixty human incisor teeth were divided into 4 groups (n=15). In groups A and C, Clearfil SE bond with light curing direction from buccal was used for bonding a composite resin to dentin. In groups B and D, Prime & Bond NT with light curing direction from composite was used. After thermocycling the specimens were subjected to tensile force until debonding occurred and values for microtensile bond strength were recorded. The data were analyzed using two-way ANOVA and Tukey post hoc test.

Results: The findings showed that the bond strength of Clearfil SE bond was significantly higher than that of Prime&Bond NT (P<0.001). There was no significant difference between light curing directions (P=0.132).

Conclusion: Light curing direction did not have significant effect on the bond strength. Sixth generation adhesives was more successful than fifth generation in terms of bond strength to dentin.

Background and Aims: Reliable bonding between tooth substrate and zirconia-based ceramic restorations is always of great importance. The laser might be useful for treatment of ceramic surfaces. The aim of the present study was to investigate the effect of laser irradiation on the shear bond strength of zirconia ceramic surface to dentin.

Materials and Methods: In this experimental in vitro study, 40 Cercon zirconia ceramic blocks were fabricated. The surface treatment was performed using sandblasting with 50-micrometer Al2O3, CO₂ laser, or Nd:YAG laser in each test groups. After that, the specimens were cemented to human dentin with resin cement. The shear bond strength of ceramics to dentin was determined and failure mode of each specimen was analyzed by stereo-microscope and SEM investigations. The data were statistically analyzed by one-way analysis of variance and Tukey multiple comparisons. The surface morphology of one specimen from each group was investigated under SEM.

Results: The mean shear bond strength of zirconia ceramic to dentin was 7.79±3.03, 9.85±4.69, 14.92±4.48 MPa for CO₂ irradiated, Nd:YAG irradiated, and sandblasted specimens, respectively. Significant differences were noted between CO₂ (P=0.001) and Nd:YAG laser (P=0.017) irradiated specimens with sandblasted specimens. No significant differences were observed between two laser methods (P=0.47). The mode of bond failure was predominantly adhesive in test groups (CO₂ irradiated specimens: 75%, Nd:YAG irradiated: 66.7%, and sandblasting: 41.7%).

Conclusion: Under the limitations of the present study, surface treatment of zirconia ceramics using CO₂ and Nd:YAG lasers was not able to produce adequate bond strength with dentin surfaces in comparison to sandblasting technique. Therefore, the use of lasers with the mentioned parameters may not be recommended for the surface treatment of Cercon ceramics.

Background and Aims: Since impression materials usually contact with saliva, blood, and oral soft tissues, their microbial contamination are harmful in immunocompromised patients. The aim of the present study was to determine the bacterial and fungal contamination in common impression materials.

Materials and Methods: In current lab trial study, 5 different samples from each 4 impression materials were homogenized in 1 ml Tween 80 and then 100µl of each sample were cultured onto blood agar, EMB, or sabouraud dextrose agar. Bacterial and fungal cultures were incubated at 37º C and 30º C, respectively. The isolated bacterial and fungal colonies were enumerated and identified using specific diagnostic media and tests. Data were analyzed using Kruskal-Wallis test.

Results: Totally 75% of samples had one or several bacterial contaminations. Iranian alginate and Speedex (putty) were the most contaminated samples. On the other hand, Speedex (light body) and foreign alginate showed lower contamination. Species of Micrococcus, Staphylococcus, Bacilluses, Corynebacteria, gram negative Citrobacter, Actinomycetes and Neisseria were isolated from the analyzed impression materials. Aspergillus, Penicillium, Alternaria, Cladosporium and Sepdonium were the fungi isolated from impression materials. Statistical significant difference was shown between bacterial contamination of Iranian and foreign alginates (P=0.001). There was no statistical significant differences between the bacterial and fungal isolated colonies (CFU/gr) of 4 tested impression materials (P=0.21).

Conclusion: Several opportunistic bacteria and fungi were isolated from impression materials especially from Iranian alginate and Speedex putty which indicated their contamination.

Background and Aims: When composite resin polymerizes, shrinkage stresses tend to produce gaps at the tooth/ restoration interfaces. Surface sealants may reduce or avoid problems related to the marginal interface. The aim of this study was to evaluate the effect of two different surface sealants (Fortify and Optiguard) on the microleakage of class V resin composite restorations.

Materials and Methods: Twenty three sound noncarious molars were collected. Totally, 45 Class V cavities with the occlusal margins in enamel and cervical margins in cementum were prepared in both buccal and lingual surfaces. The specimens were randomly assigned in three groups (15 cavities in each group) and then restored with a resin composite. After the finishing and polishing procedures, the restorations in each group were covered with a specific surface sealant, except for the control samples, which were not sealed. After placing restorations, the specimens were thermocycled and then immersed in a 50% silver nitrate solution (tracer agent) for four hours, sectioned longitudinally and analyzed for leakage using a stereomicroscope in a blind manner. The marginal microleakage was evaluated at the occlusal and cervical interfaces and compared among the three groups using the Kruskall-Wallis and the Mann-Whitney U tests.

Results: Microleakage was found in all groups at both occlusal and cervical margins. Significantly greater leakage was observed at the cervical margins compared to the enamel margins of the material groups (P=0.005). There was no statistically significant difference among the groups at occlusal margins (P=0.66). In the cervical region, Fortify showed improved results and statistically presented the lowest degree of microleakage (P=0.003).

Conclusion: The used sealant materials presented different rates of effectiveness and Fortify decreased marginal microleakage significantly.