مجله دانشکده دندان پزشکی اصفهان
سال هشتم شماره 3 (پیاپی 31، امرداد 1391)

The aim of the present study was to compare some clinical parameters in patients with mild to moderate periodontitis treated by SRP with the use of 20 mg of doxycycline. In this randomized double-blind clinical trial، 44 patients with mild to moderate periodontitis were treated with standard SRP therapy. Then the patients randomly received either adjunctive 20 mg of doxycycline or a placebo twice daily for 3 months. Before and after treatment clinical parameters، including periodontal pocket depth (PPD)، clinical attachment loss (CAL)، bleeding on probing (BOP) and modified gingival index (MGI)، were recorded. Data were analyzed using SPSS software and Mann-Whitney test، paired t-test and chi-squared test (α = 0. 05). Clinical parameters of both case and control groups significantly improved during the study (p value < 0. 001). Doxycycline-treated group exhibited significantly higher PPD reduction، increased clinical attachment gain، and BOP and MGI reduction compared to the placebo group after 3 months (p value < 0. 001). Under the limitations of the present study، 20 mg of doxycycline as an adjunct to SRP resulted in significantly greater clinical benefits compared to SRP alone in the treatment of mild periodontitis.

Since it is not possible to form an adequate micromechanical bond between resin cement and zirconia ceramics using common surface treatment techniques، laser pretreatment has been suggested for zirconia ceramic surfaces. The aim of this study was to evaluate the effect of CO2 laser treatment on primary shear bond strength (sbs) of resin cement to zirconia ceramic. In this in vitro study thirty discs of ziconia with a diameter of 6 mm and a thickness of 2 mm were randomly divided into two groups of 15. In the test group the zirconia disc surfaces were irradiated by CO2 laser with an output power of 3 W and energy density of 265. 39 j/cm2. Composite resin discs were fabricated by plastic molds، measuring 3 mm in diameter and 2 mm in thickness and were cemented on zirconia disk surfaces with Panavia F2. 0 resin cement (Kuraray Co. Ltd، Osaka، Japan). Shear bond strength was measured by a universal testing machine at a crosshead speed of 0. 5 mm/min. The failure mode was assessed under a stereomicroscope at ×40. Surface morphologies of two specimens of the test group were evaluated under SEM before and after laser pretreatment. Data was analyzed by paired samples t-test (p value < 0. 05). The mean sbs values of the laser and control groups were 12. 12 ± 3. 02 and 5. 97 ± 1. 14 MPa، respectively. Surface treatment with CO2 laser significantly increased sbs between resin cement and zirconia ceramic (p value = 0. 001). Under the limitations of this study، surface treatment with CO2 laser increased the sbs between resin cement and the zirconia ceramic.

Recently a new root-end filling material (NREFM), referred to as Cold Ceramic (CC), has been introduced; different studies have shown its biocompatibility, low cytotoxicity and good sealability. One of the disadvantages of CC is its low radiopacity in clinical procedures. The aim of this study was to evaluate radiopacity of CC by incorporating different radiopacifiers (Bi2O3, BaSo4) in comparison to Pro-root MTA and PC. In this in vitro study 7 groups of materials (Group 1: 0.9 NREFM + 0.1 gr Bi2O3; Group 2: 0.8 gr NREFM + 0.2 gr Bi2O3; Group 3: 0.9 NREFM + 0.1 gr BaSo4; Group 4: 0.8 gr NREFM + 0.2 gr BaSo4; Group 5: NREFM; Group 6: Pro-root MTA; Group 7: PC) were mixed with 0.3 mL of distilled water and placed in Teflon rings measuring 10 mm in internal diameter and 1 mm in thickness, based on ISO 6876/2001 and allowed to set. The samples were placed on PSP cassettes adjacent to a step-wedge graduated aluminum plate and radiographed. The radiographic density was determined using Digora and Scannora software programs. Data were analyzed by SPSS using Kruskal-Wallis and Mann-Whitney tests (α = 0.05). Group 6 exhibited the highest radiopacity (6.85 mm Al) and PC samples exhibited the lowest radiopacity (2.74 mm Al). All the materials tested exhibited acceptable radiopacity except for PC. A combination of 0.9 gr NREFM + 0.1 gr Bi2O3 has radiopacity comparable to that of Pro-root MTA.

A good radiograph with appropriate tube angulation can provide the dental practitioner with useful data، especially in multi-rooted teeth. The aim of this study was to compare three techniques of mesial tube shift، parallel and bisecting angle in preventing superimposition of zygomatic arch and the buccal and palatal roots of maxillary second molars on periapical radiographs.

In this cross-sectional research، 240 periapical radiographs were taken with the mesial tube shift، parallel and bisecting techniques، from 80 maxillary second molars (80 radiographs from each technique). Each radiograph was scored from 0 to 4، based on superimposition of zygomatic arch and the roots. Chi-squared test was used for data analysis (α = 0. 05).

The results of this research showed that in 73. 8% of cases the parallel technique had separated the root canals from the zygomatic arch; the separation was 57. 7% in the mesial tube shift technique but only 40% in the bisecting angle technique. There were statistically significant differences between the three techniques (p value < 0. 05).

Based on the results of this study، in the mesial tube shift technique separation of zygomatic arch from the roots of maxillary second molars was observed، but roots were superimposed on each other. However، in the parallel technique the roots and the zygomatic arch were separated without any superimposition. Mesial tube shift technique is the second choice in patients in which the parallel technique is not feasible; the bisecting angle technique is not recommended because of the superimposition of zygomatic arch on the roots.

There is decreased bond strength of composite resin to bleached enamel. Application of some anti-oxidants reduces the effect of bleaching agents and improves the bond strength of composite resin to enamel. The aim of the present study was to evaluate the effect of epigallocatechin gallat (EGCG) on the shear bond strength of composite resin to bleached enamel.

Ninety labial surfaces of maxillary incisors were randomly divided into 9 groups after polishing in the present in vitro study as follows: G1: control (no bleaching); G2: bleaching and storage for 24 hours; G3: bleaching and storage for seven days; G4-G6: bleaching and application of 600، 800 and 1000 μmol of EGCG-containing solutions for 10 minutes; G7-G9: bleaching and application of 600، 800 and 1000 μmol of EGCG-containing solutions for 20 minutes. The specimens were bleached with 30% hydrogen peroxide gel for 30 minutes; a composite resin cylinder was bonded on each specimen using a bonding agent. Shear bond strengths of the samples were measured in MPa. Data was analyzed using two-way ANOVA and Mann-Whitney tests (α = 0. 05).

Maximum (12. 98 ± 3. 28) and minimum (5. 18 ± 1. 04) mean shear bond strengths were observed in G1 and G2، respectively. There were no significant effects of time، concentration and their interactions on bond strength (p value > 0. 05). Two-by-two comparison of groups did not reveal any significant differences between the groups except for G2 and all the other groups (p value <0. 001)، G4 and G1 (p value = 0. 009)، G3 and G4 (p value = 0. 015).

There is a significant decrease in bond strength of composite to enamel immediately after bleaching. A delay of one week before bonding and use of EGCG might increase bond strength of composite resin to bleached enamel.

A main problem in the treatment of patients with skeletal Class III malocclusion is making the decision whether only orthodontic therapy or a combination of orthodontic therapy and surgery will solve the problem، which usually has to be made at a young age. The aim of this study was to evaluate the relationship between the frontal sinus surface area and size of mandible in adults to assess the possibility of the use of this anatomic structure as an indicator for prediction of mandibular growth in future studies. In this cross-sectional study، 71 cephalograms from a private orthodontic clinic were analyzed، consisting of 20 adults with skeletal Class I، 19 adults with skeletal Class II and 32 adult patients with skeletal Class III malocclusions of both male and female subjects. The surface area of the frontal sinus (mm2)، SNA، SNB، ANB، Wits، overjet، saddle angle، gonial angle، facial angle، mandibular length and body length were assessed on cephalograms. Pearson’s correlation test was used to assess the relationship between frontal sinus area and other cephalometric indices at a significant level of 0. 95. The results revealed significant direct relationships between frontal sinus size and SNB، gonial angle، facial angle، body length and mandibular length and inverse relationships with ANB، Wits and overjet. The frontal sinus area showed the highest correlations with mandibular length (r = 0. 69) and body length (r = 0. 60) (p value < 0. 0001). The frontal sinus surface area can possibly be used as an additional indicator for predicting the final mandibular size، with a valuable role in the diagnosis and treatment planning.

“Geographic tongue” or benign migratory glossitis is a tongue disorder which causes pain and dysfunction and its persistence leads to cancer phobia. Based on some reports، hormones (especially female sex hormones) are associated with geographic tongue development or exacerbation. Geographic tongue might be confused with lichen planus and candidiasis. The aim of this study was to evaluate the association of the lesion with pregnancy and its changes during each trimester. In this descriptive، analytical and cross-sectional study، 451 eligible cases were selected. After clinical examination and completion of questionnaires، if geographic tongue was diagnosed، photographs were taken and compared between the three trimesters. Data was analyzed with chi-squared test and Pearson’s correlation coefficient at a confidence interval of 95%. The prevalence of geographic tongue in pregnant women was 36. 8%. There were no significant relationships between the number of pregnancies، age and the frequency of the lesions. However، there was a significant relationship between the ectopic lesions and the fissured tongue (p value = 0. 001) and also between the gestational age and geographic tongue lesions (p value = 0. 043). The lesions were most prevalent in the second trimester، but in third trimester، prevalence of severs lesions decreased. Under the limitations of the present study، prevalence of geographic tongue in pregnant women was higher than previous reports in other communities. Severe lesions were more prevalent in the second trimester.

Color match between the restoration and the patient’s natural teeth has always been a source of concern in esthetic dentistry. One of the reasons for a lack of color match between the restoration and the natural teeth is the type of the alloy used in the metallic structure of the restoration. The aim of this study was to assess and compare the effect of 4 alloys on the color of the overlying porcelain: Degobond 4 from the high noble group، Begopal from the high-palladium group، and Super Cast and Minalux from the nickel-chromium base metal group. In this in vitro study، twenty disks، measuring 2 mm in thickness and 10 mm in diameter، were prepared (5 samples from each alloy). Then Vita 3DMaster 3M2 porcelain was placed on the samples. In addition، 5 control samples، measuring 2 mm in thickness، were prepared from the porcelain. A spectrophotometer was used to determine sample colors، which were evaluated based on CIELAB system. Data was analyzed with one-way ANOVA and Tukey test (α = 0. 05). The four alloys in this study exhibited significant differences in a* and b* values from the control group (p value < 0. 001). The alloy groups did not exhibit any significant differences from each other in a* and b* values (p value > 0. 05). There were significant differences in L* values between Supercast and Begopal (p value = 0. 009) and between Begopal and the control (p value = 0. 013) groups. There were no significant differences in ∆E between the alloys. The type of the alloy has an effect on the final color of porcelain; however، this color difference is clinically acceptable.

Dental composite resins، as the name implies، are composite materials composed of organic and inorganic elements. The main components of dental composites are polymers، organic and inorganic filers، an initiator and an activator. In addition، some elements، referred to as silanes، are added to the surface of non-organic phases or fillers of composite resins for a stable bond between the two organic and inorganic phases. The aim of this study was to review the chemical structure of dental composites with a special emphasis on nano-composites and new composites. Review Report: This review was carried out by running a search in various databases including Pubmed and ISI Web of Science from 1987 to 2010 using the key words dental composites، nano-composite and chemical structure. In the recent decade، major changes have taken place in the chemical structure of dental composites; these changes include fluoride- and calcium phosphate-releasing nano-composites and use of nano-molecular processes to construct tooth enamel by using nano-rods، nano-spheres and amelogenin. With a proper knowledge of changes in the chemical structure of dental composites، clinical behavior of these materials can be evaluated more properly. It appears that new changes are going to have important effects on the clinical behavior of newly introduced composites; however، further research is required in this respect.

Ameloblastic fibroma (AF) is a benign odontogenic tumor with mixed epithelial and mesenchymal origin; it most frequently occurs in the posterior region of the mandible، usually during the first two decades of life. AF is associated with an impacted tooth. Therefore، it might retard tooth eruption or alter the tooth eruption sequence. Case Report: In this report a case of AF on the left side of mandible in a 22-year-old woman is presented; the case was treated with radical excision because of invasive behavior and destruction of the cortex.

Conservative treatment is suggested for AF most frequently. However، in this case although malignant changes were not detected in microscopic views، radiographic views showed invasive behavior because of destruction of the buccal cortex. Therefore، radical treatment was carried out to prevent invasion and reduce the chance of recurrence.