Showing 29 results for Teeth
Mr. Eshraghian , B. Kanzali ,
Volume 11, Issue 3 (6-1998)
Abstract
The purpose of this article is to study distribution of DMF(T) and its D,M and F protions exactllly. 1500 subjects were examined clinicaly. They were 5 to 70 years old, with average 24 years. Only cavitated and coronal dental caries included in this research.
The results of this study are:
1. The caries lesions of upper and lower second permolars are equal.
2. Anterior to second premolars, the DMF(T) of upper jaw teeth is higher than lower jaw's one. Conversely posterior to second premolars, lower jaw teeth has higher DMF(T).
3. Deciduous teeth of females have lower DMF(T).
4. Permanent teeth of females have higher DMF(T).
5. The upper Canines of females are exceptions. Upper canines of females have lower DMF(T) than males' ones.
6. It seems that sex hormones influence DMF(T) through Saliva and eruption time of teeth.
7. Susceptibility to Caries relates to microbial plaque formation and salivary protection.
8. The females have more filled teeth than males.
M. Paknejad , R. Amini ,
Volume 12, Issue 2 (9-1999)
Abstract
The root trunk (RT) of molar teeth is important diagnostic parameter that has a key roll in diagnosis and treatment planning.The purpose of this study is presenting a normal index of RT in mandibular molar teeth in different buccal (B). distal (D), Lingual (Li) and mesial (M) entrances, and to compare them with each other.It is a case series study that 351 extracted molar teeth, after removal of soft tissue and debridement of calculus, evaluated with gauge (with accuracy 0.1 mm) According to our measurement:In maxilla: M-side: 3.88± 0.15 mm, B-side: 4.7± 1.7. D- side: 4.87± 0.13mm. So with P.value <0.05 M and D RT are longer than and M RT is shorter than D RT.In mandibule: B- side: 2.73± 0.11mm and L side: 4.03±- 0.13mm. So with P.value < 0.01 Li RT is longer than B RT.According to ochsenbine classification our studying teeth have medium to long RT. We prescribe for educating the crater therapy in periodontal surgery the emphasize must be focused on craters with medium and long RT.The shortness of RT in B-side of lower molars needed the most attention during osteoctomy in resective procedures. Because RT not depended to underlying factors such as age, social and economic situation,and for large amount of sample size in our study, the result could be extended in Tehran.
A. Kowsari , B. Seraj , N. Pasdar ,
Volume 15, Issue 1 (3-2002)
Abstract
Due to the differences in the composite and morphology of dentin in primary and permanent teeth, it is necessary to make improvements in bonding techniques to promote the strength of composite resins bonded to the dentinal surface, in primary teeth. The use of lower radiation, to make structural and chemical changes in dentinal surfaces has been investigated. This research was conducted to evaluate the shear strength of the composite bonded to primary teeth dentin after Nd: YAG laser radiation and acid etching for conditioning. Peripheral dentin of the buccal and lingua! surfaces of 60 extracted posterior primary teeth were exposed and polished with 600 grit with Sic paper. The teeth were divided randomly in 3 groups of 20 teeth. In group 1 etching gel, primer and adhesive of scotch bond multipurpose system (SMP), in group 2 laser at 1.6 w and 80 mj/pulse, and in group 3 laser at 2 s and 700 mj/pulse were used. Moreover, in groups 2 and 3, after laser radiation, acid etching, primer and adhesive of SMP system were applied. After necessary laboratory tests, the mean shear bond strength in MPa were 20.99±5.3 (group 1), 23.82±6.31 (group 2) and 26.58±5.59 (group 3). ANOVA, scheffe, tukey statistical tests showed that the bond strengths of group 3 were statistically higher than group 1. The frequency of dentin cohesive failures were significantly higher in groups 2 and 3, compared to group 1 that indicates a higher bond strength in these groups. Scanning electron mirographs of laser radiated surfaces, show a porous and rough surface morphology that enhances the mechanical bond of the composite.
M. Ghavamnasiri , Saa. Hosseini , H. Farzaneh ,
Volume 16, Issue 1 (4-2003)
Abstract
Statement Problem: A few studies have been conducted about bioglass posts.
Aim: The aim of this study was to compare bioglass posts with prefabricated metallic posts in clinical performance of extensive composite restorations for anterior endodontically treated teeth.
Materials and Methods: Sixty endodontocally maxillary anterior teeth, with horizontally or vertically destruction, were selected. Teeth were divided into two groups based on the kind of post: Metallic prefabricated parapost and bioglass post. Each group was divided into three subgroups based on anterior bite: normal, deep bite and edge to edge. Gutta-percha was removed from 2/3 of canal length for parapost and 1/3 for bioglass post. After etching with phosphoric-acid (37%) and applying dentine bonding syntac, Duo cement was used for the adhesion of bioglass post and a self cured composite (Degufil) for parapost. Restoration was done with a hybrid composite (Heliomolar). Follow up studies, radio-graphically and clinically, were done every three months for a 1.5-year period. Exact Fisher and Pearson tests were used for data analysis.
Results: Apical lesion was not observed in any of the radiographs. Post seal was increased by resin cement and dentin bonding agent. Post type did not significantly affect on the clinical success rate of the restorations. The retention of restoration, for both posts, was the same. Crown destruction had no significant effect on success rate. The type of anterior bite had a significant effect on success rate, as the total 6.6% failure rate was related to the patients with anterior deep bite.
Conclusion: It is suggested to use metallic paraposts and bioglass posts, in extensive composite restorations for patients with deep-bite, more conservatively.
M. Zarringhalam ,
Volume 17, Issue 3 (8-2004)
Abstract
Statement of Problem: In some cases, a difference in size between the right and left teeth, during band selection for first molars, is observed.
Purpose: The aim of this study was to measure the mesiodistal width and to compare the teeth on left and right sides of jaws in individuals with normal occlusion, according to the sex.
Materials and Methods: In this cross-sectional study, sixty students (30 males and 30 females), age ranging from 16-18 with the mean age of 17.3, were selected through cluster random sampling from Mashhad high schools. The mesiodistal width of 1440 teeth, from the distal of first molar on right side to the distal of first molar on the left, were measured on study casts. Data were analyzed using paired t-test and Independent sample t-test.
Results: In upper jaw, mean of the mesiodistal width of each tooth on the right side was less than its counterpart on the left side except for the right second premolar which its width was more than that of the left one although the differences were not statistically significant. In lower jaw, mean of the mesiodistal width of each tooth on right side was more than the same tooth on the left except for the canines and second premolars. The differences were not significant. Generally the mesiodistal width of each tooth in males was more than its counterpart in females with a specially significant difference for canines and first molars.
Conclusion: According to this study, there was a little difference in me siodistal width of teeth between the left and right sides. In upper jaw, the majority of teeth on the right side were smaller than the left ones whereas in lower jaw the right side ones were larger than the left ones. Therefore, dental asymmetry in both jaws, on the left and right sides, were opposite. Comparing males and females, each tooth in males was larger than the same one in females and especially for canines and first molars the difference was significant. As a result dental asymmetry should be considered in orthodontic treatments.
M. Memarian , R. Masoomi ,
Volume 17, Issue 4 (1-2005)
Abstract
Statement of Problem: Choosing an appropriate tooth for edentulous patients is a very important step in dentistry.
Purpose: This research has been done for determination of proper procedure for tooth selection in edentulous patients.
Methods and Materials: In this cross- sectional study 100 student and people who have come to a medical
center (range 20-30 years old) were collected randomly and the size of their anterior teeth were determined. A gauge with 0.01 mm accuracy and flexible plastic millimeter was used in order for measurement of anatomic landmark. For achieving the relation between the sizes of teeth statistical analysis was done.
Results: 50% of patients were female and the other 50% were male. We found a relationship between mesiodistal width of six maxillary anterior teeth and mesiodistal width of six mandibuMary teeth that can be shown as follow In men: six mandibular anterior teeth width= 0.S3 * width of six maxillary anterior teeth -2.008 In women: six mandibular anterior teeth width- 0.56 * width of six maxillary anterior teeth + 9.53 Also strong meaningful relationships between width of six anterior maxillary teeth and the width between corners of the lip in curve position have been noticed only in men which can be show' as follow:width of Six mandibular anterior tceth= 39.63 + 0.21+ the width between corners of lip in curve position for men
Conclusion: Although there are different ways for prediction of teeth size, it seems these findings can be
helpful in determining and prediction of it.
F. Shafiei , M. Mortazavi , M. Memarpoor ,
Volume 19, Issue 1 (4-2006)
Abstract
Background and Aim: Although the use of adhesive systems can be effective in decreasing microleakge, it is still a major problem in composite resin restorations. The aim of the present study was to evaluate the marginal sealing ability of resin composite restorations using four dentin bonding systems in both primary and permanent teeth.
Materials and Methods: In this experimental study, one hundred and sixty extracted human teeth (80 primary and 80 permanent) were selected. All of the samples received a class V cavity preparation on the buccal surfaces (The coronal half in enamel and the gingival half in cementum or dentin). Each group was then divided into four subgroups each containing 20 teeth. Four different dentin bonding systems (Scotchbond Multipurpose, Single Bond, Clearfil SE Bond and Prompt L-Pop) were used in each subgroup. Then the cavities were filled with composite resin (Z100 for SBMP and Clearfil AP-X for Clearfil SE Bond). Samples were thermocycled, immersed in 0.5% basic fuschin, cut faciolingually and evaluated for dye penetration using a binocular stereomicroscope. Kruskal-Wallis and Dunn tests were used for comparison of microleakage between groups with p<0.05 as the limit of significance.
Results: The results showed that: There was significant difference in microleakage among four adhesive systems in both incisal and gingival margins of permanent teeth and in incisal margin of primary teeth (P=0.000, P=0.002, P=0.000 respectively). There was no significant difference in microleakage of restorations with each of four systems between permanent and primary teeth in both incisal and gingival margins except for PLP, which showed a significant different microleakage in the cervical margins (P=0.009). PLP showed better cervical seal in primary teeth compared to permanent teeth. Clearfil SE Bond showed acceptable results at incisal and cervical margins in primary teeth in comparison to other bonding systems.
Conclusion: Based on the results of this study, CSEB, SB and SBMP systems showed acceptable clinical results in primary and permanent teeth. Only PLP showed weak results in reducing microleakage. CSEB can be used successfully in primary teeth because of simplicity and reducing leakage in primary dentin and enamel.
K. Khosravi , Mr. Malekipour, F. Shirani ,
Volume 19, Issue 3 (6-2006)
Abstract
Background and Aim: The structural rehabilitation of a pulpless tooth is critically important to ensure a successful restorative outcome following endodontic treatment. A post and core is often indicated for the retention and reinforcement of the final restoration. But, the clinical situation is significantly challenging if the root exhibits immature development or there is a thin root wall that can compromise the prognosis for a long- term successful treatment. The purpose of this in vitro study was to evaluate different methods of intraradicular reinforcement in structurally compromised roots.
Materials and Methods: In this experimental study, seventy two extracted intact maxillary central incisors with similar size, shape and root anatomy were selected. After root canal therapy in 60 teeth, an acrylic laboratory bur was used to thin the cervical area and simulate the thin dentinal walls of immature teeth. The preparation was performed through the palatal access and extended 5mm apical to CEJ. The remaining 12 teeth remained unprepared to serve as positive control group. Cases were randomly divided into six groups of 12 teeth each and restored as follows. In the 12 cervically unprepared teeth (positive controls) the composite resin with dentin bonding agent (DBA) was placed in access cavity and cured for 120 seconds. This technique was also applied to other groups when the access was restored with composite. In the second group, the access cavity was restored with composite only to the level of CEJ. In the third group the cervically prepared teeth were reinforced with cement resin (Enforce) and a prefabricated post was placed in 5mm apical to the CEJ. In the fourth group, the cervically prepared teeth were reinforced with composite resin and DBA by a clear plastic post. In the fifth group the cervically prepared teeth were reinforced with composite resin and dba and a cast post. In the sixth group the cervically prepared teeth were restored with composite resin and dba with a prefabricated post. All of the specimens were mounted by rubberized technique and tested in the Instron universal testing machine. The fracture loads in samples were analyzed with ANOVA and Duncan tests with p<0.05 as the limit of significance.
Results: Significant differences in fracture resistance were observed between the first and second groups compared with others. The highest fracture resistance values were recorded for first group while the lowest were registered for the second group. Fracture resistance of the third, fourth and fifth groups had no significant statistical differences with others and fracture resistance of sixth group was the highest with significant difference (P<0.05).
Conclusion: From this study, it may be concluded that the use of a dba and a composite resin in thin-walled roots reinforces the immature teeth and facilitates the use of post.
A. Makarem , M. Ghavam Nassiri , M. Esmaili ,
Volume 19, Issue 4 (1-2007)
Abstract
Background and Aim: Nanoleakage can cause discoloration around restoration margins, secondary caries, postoperative sensitivity and finally loss of restoration, thus adequate hybrid layer is of primary importance in prevention of nanoleakage in adhesive restorations. Because of structural differences between primary and permanent dentin, evaluation of nanoleakge in primary teeth is very important. The aim of this study was to evaluate the nanoleakage in composite restorations following application of self -etch and total-etch adhesives in primary and permanent teeth.
Materials and Methods: In this experimental study, Cl V cavities were prepared in buccal surfaces of 20 extracted primary molars and 20 extracted premolars. Each group was divided into 2 subgroups: In group (A), Gluma One Bond and in group (B), iBond adhesive materials were applied. After silver nitrate staining, specimens were mesiodistally sectioned and polished and then SEM examination was carried out to measure the nanoleakage .Data were analyzed statistically using, ANOVA and Duncan tests with p<0.05 as the limit of significance.
Results: Factors tested had no significant effect on each other. Primary teeth showed more nanoleakage than permanent teeth (P<0.05). Mean nanoleakage was significantly higher in cervical than occlusal margins (P<0.05) and also in iBond than in Gluma One Bond in primary teeth (P<0.05). In permanent teeth, the lowest nanoleakage was observed in Gluma One Bond.
Conclusion: The result of this study indicates that the use of total etch dentin adhesives (Gluma One Bond) in bonded restorations results in less nanoleakage in primary and permanent teeth.
D. Goodarzipour, A. Saeedi, N. Bahrami,
Volume 22, Issue 3 (12-2009)
Abstract
Background and Aim: Impaction of maxillary cuspids is the most common after third molars with 1% to 3% prevalence. Localization of these impacted teeth may affect orthodontic or surgical treatment plan. Therefore, different techniques have been introduced to localize impacted canines. The present study was conducted to compare the accuracy of panoramic, tube shift and panoramic plus palpation in determination of the position of maxillary impacted canine.
Materials and Methods: 47 patients (20 females, 27 males) with the age of more than 12 years (mean age of 25.4 years old) whom referred to Dental School, Tehran University of Medical Sciences, with at least one impacted maxillary canine included. An oral and maxillofacial radiologist localized impacted canine first by using panoramic then tube shift technique blindly. After that, an oral and maxillofacial surgeon localized the canine by panoramic and palpation of the area before surgery. Data obtained from radiologist and surgeon were compared with true location of canine after surgery. Statistical analysis was done using sensitivity and specificity.
Results: Among total 47 impacted maxillary canines, 11 cases (23.4%) showed buccal impactions and 36 cases (76.6%) palatal impactions. Sensitivity (ability of technique to localize palatal impaction) of all of the techniques were same (100%) but specificity (ability of technique to localize buccal impaction) of tube shift (100%) was more than two others (0%).
Conclusion: The tube shift technique was the most accurate technique to localize maxillary unerupted canines compared to the others. Due to the ability of panoramic and panoramic with palpation in prediction of palatal canine impactions and failure of these techniques to predict buccal impactions, both methods are not suitable in localization of impacted maxillary canines and they must be used as adjunctive techniques.
R. Haghgoo, F. Abbasi,
Volume 23, Issue 1 (6-2010)
Abstract
Background and Aims: Formocresol is one of the most common pulpotomy medicaments for primary teeth. Because of its systemic and local side effects, it may be essential to use another material instead of formocresol. The aim of this study was to evaluate the histopothalogy of pulp after pulpotomy teeth with sodium hypochlorite and formocresol.
Materials and Methods: In this randomized clinical trial, 22 canine teeth that must be extracted because of orthodontic treatment were selected. The teeth were randomly divided into 2 groups (n=11) and pulpotomized with formocresol or sodium hypochlorite. These teeth were extracted after 2 months and pulpal response was evaluated according to the degree of inflammation and extent of pulpal involvement. Dentinal bridge formation was also evaluated. The data were analyzed by Mann-Whitney test.
Results: In formocresol group, mild inflammation was seen in 4 and moderate inflammation in 3 and severe inflammation in 4 cases. In sodium hypochlorite group mild inflammation was seen in 6 cases and moderate inflammation in 4 cases and severe inflammation in 1 case. Mann-Whitney test revealed that this difference was not statistically significant (P>0.05). In formocresol group, necrosis was seen in 5 cases, but abscess and internal resorption were not seen in any cases. In sodium hypochlorite group, internal resorption was seen in 3 cases but necrosis and abscess were not seen in any cases. Mann-Whitney test showed that the difference between two groups was significant in terms of necrosis (P=0.02). In sodium hypochlorite group, dentinal bridge was formed in 3 cases however, no dentinal bridge formation was seen in formocresol group. Mann-Whitney test showed that this difference was not significant statistically (P>0.05).
Conclusion: Based on the results of this study, sodium hypochlorite can be used as a pulpotomy agent in primary teeth.
N. Babaee, A . Poorsattar Bejeh Mir, M. Taghibakhsh, Z. Dehghan,
Volume 23, Issue 4 (1-2011)
Abstract
Background and Aims: Multiple supernumerary teeth are rare and often found in association with syndromes such as Gardner, Cleidocranial dysplasia and cleft lip and palate, with a much less chance for isolated non-syndromic cases. The aim of this study was to report a case with 6 supernumerary teeth without syndromic association.
Case Report: The patient was a 33 year-old female, referred to oral diseases and diagnosis department with chief complaint of sensitivity to cold and hot food in right upper premolar region. Oral examination revealed 5 erupted lingually supernumerary teeth (four in mandibular and one in maxillary premolar region, respectively). Further panoramic radiography clarified an extra impacted tooth in the palatal region of left premolar maxillary area. All extra teeth had been appeared since the age of 17 during one year, as the patient claimed. Medical history and thorough clinical and paraclinical examinations were not significant except for the hypothyroidism, since 5 years ago. No other family member noticed to be the case. Based on our findings, a diagnosis of non-syndromic multiple supernumerary teeth was established.
Conclusion: A thorough examination of each patient presented with supernumerary teeth, including panoramic and intraoral radiographic images may provide valuable information regarding accompanying syndromes and unerupted teeth. Early diagnosis is an essential step for orthodontic or surgical decisions making, preventing or avoiding worsening complications such as malocclusion, adjacent normal teeth delayed eruption or rotation, diasthema, cystic lesions and resorption of contiguous teeth.
L. Ghahramani, S. Shahabi, A. Amirjan, A Fazel,
Volume 23, Issue 4 (1-2011)
Abstract
Background and Aims: Failure of bonding between artificial teeth and denture base material is a considerable problem for patients who wear dentures. Because of the cost of denture repair and the expensive price of foreign artificial teeth, this study was designed to compare the bond strength of composite and acrylic artificial teeth with heat-cured and auto-polymerized denture base resins.
Materials and Methods: In this experimental and in vitro study, two type of acrylic resin (heat-cured: Selectaplus H/ Trevalon, Dentsply and auto-polymerized: Rapid Repair, Dentsply) and four artificial teeth (acrylic Marjan New, composite Glamour teeth which both of them are Iranian) and Ivoclar acrylic and composite teeth were used. Therefore, 8 groups of 14 specimens each were evaluated. A shear bond strenghth test in a Universal Testing Machine was used. Data were analyzed using the 2-way ANOVA test.
Results: The bond strengths of acrylic teeth (Marjan New and Ivoclar) to heat-cured resin were similar (P=0.632) and statistically higher than those of composite teeth (Glamour and Ivoclar). Acrylic teeth (Marjan New and Ivoclar) and Glamour teeth had similar bond strength to auto-polymerized resin, which showed the highest bond strength values. Ivoclar composite teeth showed significantly the lowest bond strength (P<0.05). All acrylic teeth had the highest mean bond strengths to heat-cured resin which were significantly different from that of
auto-polymerized resin (P<0.05). However, the bond strengths of all composite teeth to both denture base resins were not significantly different (P>0.05).
Conclusion: Based on the results of this study, the type of denture base material and artificial tooth may influence the failure load.
Z. Bahrololoomi, Aa. Soleymani, P. Namiranian,
Volume 24, Issue 2 (4-2011)
Abstract
Background and Aims: Use of glass ionomer cements in pediatric dentistry is increasing and limited information exists with regard to the effect of salivary contamination on the shear bond strength of glass-ionomer to dentin in primary teeth. The aim of this study was to evaluate the effect of salivary contamination on the shear bond strength of two types of glass ionomer cements to dentin in primary teeth.
Materials and Methods: A total of 36 human extracted primary molars were used in this study. The specimens were divided into two groups for each material and then further subdivided into three groups: group 1: uncontaminated, group 2: contaminated with saliva, group 3: contaminated, washed and air dried. The specimens in groups I, II, III were bonded to glass-ionomer and in groups IV, V, VI to resin modified glass-ionomer. Shear bond strength was measured using an Instron machine at 1 mm/min cross head speed. Data were analyzed with ANOVA and Tukey test.
Results: There were significant differences in the mean shear bond strength among groups IV, V (P=0.05). There were no significant difference among groups I & II (P=0.16), I & III (P= 0.93) and IV & VI (P=0.98).
Conclusion: Results showed that salivary contamination can decrease the mean shear bond strength of light- cured glass-ionomer to dentin in primary teeth.
Fahime Tabatabaei,
Volume 25, Issue 1 (4-2012)
Abstract
Dentistry has been a field dominated by a constant improvement of synthetic biomaterials. Tissue engineering of tooth is coming to change the panel of the dental materials such as restorative materials and implants. Certainly, it is the largest transition in history of dental materials science in terms of accepting this new and exciting technology. The objective of this article is to present various implications of tissue engineering in different fields of dentistry. To achieve this goal, a review of the literature was carried out by using Medline database to search topics including "dental stem cells", "teeth tissue engineering", "regenerative dentistry", "oral surgery", "periodontal regeneration" and "regenerative endodontics". These searches were limited to articles published after the year 2000. On the basis of our literature review, we have found that although there are significant challenges in oral tissues engineering, engineered tissues will find many applications in dentistry within the next few years.
Jalil Modaresi, Amir Reza Heshmat Mohajer, Hossein Aghili, Morteza Khorshidi, Faramarz Rostami Chavoshlo, Amirmohamad Mahabadi,
Volume 25, Issue 3 (7-2012)
Abstract
Background and Aims: Electric pulp testing is used for diagnosis of the pulp status. This test is technique sensitive and hence may elicit positive or negative false response in case of inaccurate use. The optimal site for placement of the probe tip has not been determined. The aim of this study was to evaluate the effect of pulp tester probe placement site on the response of maxillary teeth.
Materials and Methods: A total of 378 teeth (126 central incisors, 126 lateral incisors and 126 canines) in 67 voluntary 20-35 year-old patients were selected. Three sites on each tooth (incisal edge, labial and lingual surfaces) were tested with an electrical pulp tester and responses were recorded. Data were analyzed by Repeated Measure ANOVA test.
Results: The central teeth showed significantly lower sensation threshold than lateral and canine teeth (P<0.001). The incisal edge of tooth were significantly more sensitive compared to labial and lingual surfaces (P=0.008).
Conclusion: This study showed that the optimum site for placement of pulp tester probe was incisal edge.
Fateme Nematollahi, Nasim Azizi, Sima Shahabi, Loghman Ghahremani, Zohre Asgari, Hossein Bagheri ,
Volume 26, Issue 2 (5-2013)
Abstract
Background and Aims: Failure of bonding between artificial teeth and denture base material is a considerable problem for patients who wear dentures. According to the different impact of artificial teeth and different information about resistance force of mastication and also with deficiency in researchs, this study was designed to compare the bond strength of composite and acrylic artificial teeth to auto-polymerized denture base resins with and without cyclic loading.
Materials and Methods: In this experimental and in vitro study, an acrylic resin auto-polymerized (Rapid Repair, Dentsply) and four artificial teeth (Acrylic Marjan new, Composite Glamour teeth and Ivoclar acrylic and composite teeth) were used. Therefore, 8 groups of 10 specimens each were evaluated. All specimens were thermocycled for 5000 cycles, in water baths between 5 and 55 ◦ C. Half the specimens in each group were treated with cyclic loading at 50N for 14, 400 cycles at 1.2 Hz. The shear bond strengths were measured using a Universal Testing Machine. Data were analyzed using Two-way ANOVA test.
Results: Statistical analysis demonstrated no significant effect of cyclic loading on the shear bond strength, but the type of artificial tooth affected the shear bond strength (P=0.006). Also, the interaction between Cyclic loading and the type of artificial tooth showed no significant difference (P=0.98). Tukey test showed that acrylic teeth (Ivoclar) had statistically higher bond strength values than that of other teeth (PGlamour=0.02), (PComposite ivoclar=0.01) and (PMarjan new=0.02).
Conclusion: Within the limitation of this study, the predominant type of fracture in all groups was cohesive, therefore the bond strength was adequate in all teeth and the type of artificial tooth may influence the bond strength of denture teeth to denture base resin. Cyclic loading had no significant effect on the bond strength of denture teeth to the auto-polymerized acrylic resin.
Majid Akbari, Mohhamad Javad Moghaddas, Sara Majidinia,
Volume 27, Issue 2 (6-2014)
Abstract
Background and Aims: The aim of this study was to evaluate the fracture strength of restored teeth with three different types of E glass-fiber posts after thermo-mechanical loading.
Materials and Methods: Sixty extracted upper central incisor human teeth, with similar size, were selected and divided into three groups (n=20). Endodontic treatment was done in all groups and crowns were sectioned from 2 mm above CEJ. Then one type of posts in each group (Anthogyr, Svensk, Hetco) cemented using Panavia cement and the crowns were restored with a composite. The specimens in each group were thermocycled for 6000 cycles (5-55°C) and subjected to 1200000 cycles of mechanical loadiong in an artificial mouth machine. Then the fracture strength was measured and data were analyzed using ANOVA and T-student test (α=0.05).
Results: The mean fracture strengths in Hetco group before and after thermomechnical loading were 581.098 ± 192.742 N and 564.74±213.59 N, in Anthogyr group were 664.358 ± 135.878 N and 629.12±390.3 N and, in Svensk group were 780.258 ± 379.133 N and 779.84±282.59 N, respectively. There was no significant difference between groups and also there was no significant difference in each group before and after thermo-mechanical loading (P>0.05).
Conclusion: Restored teeth with Hetco fiber glass post were similar in terms of the fracture strength with that of two other posts after thermo-mechnical loading.
Hoorieh Bashizadeh Fakhar, Hanieh Kaviani, Mehrdad Panjnoosh, Ahmad Reza Shamshiri,
Volume 27, Issue 2 (6-2014)
Abstract
Background and Aims: It is crucial to verify the relationship between root apices and maxillary sinus floor in some surgical procedures like extraction and implant placement or in orthodontic movements like intrusion. Protrusion of roots into the sinus increases the risk of post extraction pneumatization which in turn decreases the available bone at the implant or denture sites. The aim of this study was to determine the panoramic radiology accuracy for defining the relationship between posterior root apices and the maxillary sinus floor by Cone Beam CT (CBCT).
Materials and Methods: Paired panoramic radiographs and CBCT images of 117 subjects were examined. 452 posterior maxillary roots including second premolar, first and second molar were classified by the means of the relationship with maxillary sinus floor. CBCT was used as Gold standard method, and the agreement of panoramic findings with CBCT was examined statistically. Data were analyzed using Chi-square and Multiple logistic regressions.
Results: Agreement of the panoramic and CBCT results were seen in 57.7% of all cases. Roots which had no contacts with the sinus floor (class 0) showed a high agreement of 89.5% between two imaging techniques. Roots in contact with sinus floor (class 1) showed 58.8 % and cases with root protrusion into sinus cavity (class 3, 4) showed 50% of agreement (P<0.001). Also in 36% of cases with no protrusion into the sinus cavity (class 0, 1, 2), panoramic showed protrusion. The agreement for the premolar was higher than molars (P<0.001)
Conclusion: The majority of roots which their images were projected on the sinus cavity had no vertical protrusion in CBCT cuts. Considering the results, in these cases CBCT can be recommended.
Seyed Amir Hossein Mirhashemi, Razieh Jabbarian,
Volume 27, Issue 2 (6-2014)
Abstract
The need to identify and determine the age of the unidentified dead person s or accident victims of natural disasters is clear. Also, some remedial measures in the field of orthodontics and pediatric dentistry depend on knowing the patient’s physiological age. Previous studies suggested that dental age have a good correlation with physiological age more than skeletal or o ther common methods of age determination. Among the various methods used to determine dental age , dental radiography provides wide facilities for clinicians. Being noninvasive and the ability of performing the technique on live subjects as well as simplicity and low cost and reliable results , have led researchers to investigate further on that . The formation and calcification process of teeth and changes during aging has been regarded by many, leading to introduce various methods in which the field. In this study, 36 related articles were achieved by searching PUBMED, Science Direct and Google Scholar resources and discussed. Provided what diversified means of determining age using dental radiographs is encouraged , it is recommended to be not restricted to use only one of the methods because the multilateral approach is more reliable.
