Journal of Dental Medicine

Nowadays, different materials have been used for regeneration of interosseous defects and Neo-Os is one of them. The objective of this study was to evaluate histologically the influence of Neo-Os® particles on bone regeneration using rabbit caivarias defects with and without protection of Gore-Tex® barrier membrane. A cutaneous- periosteal incision and flap was made on the forehead of 32 rabbits exposing the top o"" the skull. A standardized trans-osseous skull defect (8 mm diameter) was made in each of the parietal bone with rotating round bur. In half of the rabbits, one defect was filled with the Neo-Os® particles without any type of the barrier membrane. The other defect was left empty. In the other half of the rabbits, one defect was filled with Neo-Os® and two flat expanded polytetrafiuoroethyiene (Gore-tex®) membranes. For the other defect, only the Gore-tex membrane protected the defect. After 8 and 16 weeks, the specimens were processed using standard, decalcified, hard tissue histology techniques. Rabbit caivarias defects treated with Neo-Os® particles and polytetrafiuoroethyiene (Gore-tex®) membrane, healed by in growth of woven bone from the defect margins and by formation of bony islands within the defect area. Finally, the defects were treated with woven and lamellar bone.

Statement of Problem: One of the problems associated with the treatment of periodontal diseases is caused through the extension of disease toward furcation area. Several techniques in Conservative, Resective and Regenerative categories have been suggested for the treatment of furcation involvement.
Purpose: The aim of this study was to compare the results of the treatment of grade II furcation involvement in mandibular molars using an allograft material named 'Dynagraft' (a type of demineralized bone matrix) and the coronally positioned flap.

Materials and Methods: In this randomized controlled clinical trial study, twelve patients (9 females and 3 males), aged 25 to 40, suffering from bilaterally grade II furcation involvement of mandibular molars who referred to dental faculty Tehran University of medical Sciences, were investigated. The molars of one side were treated by Dynagraft whereas those of the opposite side underwent the CPF method. Measurements of the probing pocket depth (PPD), clinical attachment level (CAL), keratinized gingiva (KG) and horizontal probing depth (HPD) were recorded at baseline, 3 and 6 months after surgery. In order to investigate the bone radiographic changes, radiovisiography at the mentioned periods in addition to clinical investigation, were performed. For statistical analysis, Paired West was used.
Results: The mean PPD reduction three months and six months after the operation were 1.75 mm and 2.25mm, respectively in the Dynagraft (test) group whereas 1.26mm and 1.27mm in the CPF (control) group (P<0.005). The mean attachment gain three months and six months after the operation were 1.1 mm and 1.5mm respectively in the test group, and 0.2mm and 0.3mm in the control group (P<0.005). The mean KG reduction three months and six months after the operation were 0.5mm and 0.6mm respectively in the test group and those of the control group were 1.1mm and 1.1mm. The mean HPD reduction three months and six months after the operation were 1.55mm and 2mm respectively in the test group (P<0.005) and 0.55mm and 0.55mm in the control group (PO.01). Radiovisiography of the mentioned areas three months and six months after the operation confirmed the changes obtained from clinical measurements, showing appreciable reconstructive results (Bone filling) in the test group as compared with the control group. Moreover, root resorption was not observed.
Conclusion: Based on the results of this study, Dynagraft can be used as an appropriate material in the treatment of grade II furcation involvement in mandibular molars. However, for a through evaluation of such regenerative techniques in furcation involvement, further studies with larger population and long term follow up in addition to histologic studies are suggested.

Statement of Problem: Several methods are used to enhance bone repair and new bone formation, and bone matrix gelatin (BMG) is recently introduced.

Purpose: The purpose of this histologic and histomorphometric study was to assess the osteogenic potential and the quantity of new trabecular bone formation after implantation of OCP and BMG alone and in combination into the cranial defects in rat.

Materials and Methods: In this experimental study, 100 young male Sprague Dawley rats (5-6 weeks age and 120-150gr weight) were divided into four groups randomly. A full thickness standard trephine defect 5mm in diameter was made in the rat’s parietal bone, and 5mg of OCP, BMG alone and in combination were implanted into the defects. No OCP and BMG particles were implanted in control group which was otherwise treated identically. On the 5th, 7th, 14th, 21st and 56th days after implantation, the rats were killed and bone samples collected. After processing the samples by routine histological procedures, 5µm thick sections of bone were cut and stained with Haematoxyline & Eosin (H&E) and Alcian Blue and studied histologically and histomorphometrically using light microscope and eyepiece graticule. The amount of newly formed bone was quantitatively measured by the use of histomorphometric methods. Data were analyzed with SAS statistical package using ANOVA and Duncan tests.

Results: In the experimental groups, the new bone formation was initiated from the margin of defects during 5-14 days after implantation. During 14-21 days after implantation, bone marrow cavities and bone marrow tissues in newly formed bone were seen. By the end of the study, the newly formed bone increased and was relatively matured and almost all of the implanted materials were absorbed. In control group, at the end of the study, a few clusters of new bone were seen near to the defect margins and host bone. The histomorphometric analysis indicated statistical significant differences in the amount of newly formed bone between the experimental and control groups (P<0.05).

Conclusion: Implants of OCP/BMG appear to stimulate bone induction and new bone growth in bone defects greater than the other groups and these biomaterials could be used in the repair of cranial bone defects in clinical situations.

Background and Aim: It has been suggested that osteoporosis may be a predisposing factor for periodontitis and tissue destruction, thus periodontitis and mandibular bone density might be related. The purpose of the present study was to evaluate the clinical signs of periodontal tissue destruction in postmenopausal women.

Materials and Methods: In this cross-sectional study, 60 postmenopausal women (51 to 78 years of age) underwent radiographic examination of the right mandibular premolar. Mandibular bone density (MBD) was measured using optical densitometry. Periodontal status variables examined included: probing pocket depth (PPD), clinical attachment level (CAL), bleeding on probing (BOP) and plaque index (PLI). Data were analyzed by statistical tests using P<0.05 as the limit of significance.

Results: This study found no statistically significant association between the four indicators of periodontal disease and mandibular bone density, but there was statistically significant association between mandibular bone density and the number of remaining teeth. There was also statistically significant association between PPD and the number of remaining teeth.

Conclusion: These findings suggest that individuals with high MBD seem to retain teeth with deep periodontal pockets more easily than those with lower MBD.

Background and Aim: Several biomaterials have been presented for regeneration of intraosseous defects and Bio-Oss is one of the most accepted materials in this field. Neo-Oss may be the first and only regenerative material made in Iran which few studies have been published about it. The aim of this study was the histologic evaluation of Neo-Oss in comparison with Bio-Oss in experimental rabbit calvarial defects. Materials and Methods: This was an interventional in vivo study. After elevating muccoperiosteal flap 18 standard defects (3×6mm) in frontal & parietal bone were made by round bur on the calvarium of 6 New Zealand rabbits. Defects were randomly assigned to one of the following treatments: 1-No graft (control), 2-Bio-Oss graft 3-Neo-Oss graft. After 4 weeks the animals were killed and histologic sections prepared. The studied variables consisted of inflammation, type of regenerated bone, thickness of bony trabeculation and foreign body reaction. Data were analyzed by Friedman test with p<0.05 as the limit of significance.

Results: The results showed that Bio-Oss was effective for bone regeneration. Inflammation (P= 0.026) and foreign body reaction (P= 0.002) in Neo-Oss was significantly more than Bio-Oss group. Thickness of terabecula in Neo-Oss group (66.7% thin) was significantly different from Bio-Oss (100% thick) and control group (50% thin 50% thick) (P= 0.006). In Neo-Oss group, granulation tissue containing giant cells was observed and the rate of resorption during 4 weeks was high.

Conclusion: Based on the results of this study, the healing capacity of Neo-Oss in comparison with Bio-Oss is not acceptable.

Background and Aim: Unlike other bones of the head and neck, hyoid bone has no bony articulations. It is connected to mandible, cranium and pharynx through muscles and ligaments. During treatment with functional appliance in patients with class II div1 malocclusion, mandible is positioned in inferior and anterior direction. Regarding the relation between hyoid and mandibular bone, alterations of hyoid bone position can be a result of functional appliance therapy. The aim of this study was to evaluate the changes of hyoid bone position following treatment with Farmand functional appliance in patients with class II div 1 malocclusion.

Materials and Methods: In this before-after clinical trial, 28 patients with class II div 1 malocclusion which were under treatment with Farmand functional appliance for 11 months were selected. Facial growth in vertical, normal or horizontal direction was determined by cephalometric measurement. Data were analyzed with Paired-t test to compare the differences of mean values pre and post treatment. Variance analysis was used to compare the three growth patterns. P<0.05 was considered as the limit of significance.

Results: Hyoid bone shifted significantly forward in horizontal dimension (P<0.01) and non-significantly upward in vertical dimension. There was no significant difference among the three studied groups with respect to hyoid bone position alterations in horizontal dimension but significant difference was observed between horizontal and vertical growth pattern in vertical dimension (P<0.05). There was significant correlation between decrease of ANB angle and forward movement of hyoid bone.

Conclusion: Based on the results of this study, treatment with Farmand functional appliance (Fa II) leads to significant alterations in the position and anterior displacement of the hyoid bone.

Background and Aim: Multiple systemic and local factors contribute to the incidence and progression of periodontal diseases. Osteoporosis is defined as changes in trabecular bone structure and probably as a systemic risk factor of periodontitis. Since both diseases are considered as major public health problems and affect numbers of adults the aim of this study was to investigate the relationship between osteoporosis and periodontal disease and the role of oral hygiene in this process.

Materials and Methods: In this historical cohort study, 68 patients were selected from 111 individuals for whom femoral and hip BMD (Bone Mineral Density) with DXA (dual energy X-ray absorptiometry) procedure was performed and PI (Plaque Index) recorded. Cases were divided into four groups of 17 persons each as follow: osteoporotic with good oral hygiene (OH), osteoporotic with poor oral hygiene (OP) normal with good oral hygiene (NH), and normal with poor oral hygiene (NP). Clinical examinations including BOP (bleeding on probing),GR (gingival recession), PPD (probing pocket depth) and TL (tooth loss) was performed for all cases. Data were analyzed by two-way and four-way ANOVA test, with p<0.05 as the level of significance.

Results: Significant relation was observed between GR (P=0.045), and TL (P=0.050) with BMD independent of oral hygiene. Whereas such relation was not true for BOP and PPD (P=0.989).

Conclusion: Our finding showed that osteoporosis can make patients more vulnerable to periodontal diseases by reducing trabecular bone mass and is related to gingival recession as well as tooth loss.

Background and Aim: Accurate bone measurements are essential to determine the optimal size and length of dental implants. The magnification factor of radiographic images may vary with the imaging technique used. The purpose of this study was to compare the accuracy of linear tomography and panoramic radiography in vertical measurements, as well as the accuracy of linear tomography in mandibular width estimation.

Materials and Methods: In this test evaluation study, the vertical distances between the crest and the superior border of the inferior alveolar canal, marked with a metal ball, was measured by linear tomography and panoramic radiography in 23 sites of four dry mandible bones. Also the mandibular width was measured at the same sites. Then, the bones were sectioned through the marked spots and the radiographic measurements were compared with actual values.

Results: The vertical magnification factor in tomograms and panoramic radiographs was 1.79 (SD=0.17) and 1.69 (SD=0.23), respectively. The horizontal magnification of tomograms was 1.47 (SD=0.17). A significant correlation was found between the linear tomographic and actual values, regarding vertical dimensions (p<0.001, r=0.968) and width (p<0.001, r=0.813). The correlation was significant but lower in panoramic radiographs (p<0.001, r=0.795). Applying the magnification values suggested by the manufacturer, the mean difference of vertical measurements between the tomographic sections was 2.5 mm (SD=3.4) but 3.8 mm (SD=1.65) in panoramic radiographs. The mean of absolute difference in mandibular width between the tomographic sections and reality was 0.3mm (SD=1.13). In the linear tomograms, 4.3% of vertical and 56.5% of the width measurements were in the ±1mm error limit. Only 4.3% of the vertical measurements were within this range in the panthomographs. The linear regression equation between the actual values and those obtained by radiography in vertical dimensions showed that 87.5% of tomograms and 51.8% of panoramics were located in the ±1 mm error limit.

Conclusion: Based on the results of this study, the linear tomography is more accurate than panoramic radiography in mandibular height estimation. The accuracy of linear tomography in width estimation is within acceptable limits.

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 Aims: The present study was designed for evaluation of bovine demineralized bone matrix (DBM) in healing process of bone defects and comparison of bovine DBM (xenograft) and human DBM (allograft) which is used clinically.

Materials and Methods: Seven male white New Zealand rabbits were used in this study. The incision was made directly over the midsagital suture of the parietal bone. Then 3 bicortical defects were created with trephine bur No.8 (8mm diameter). The defects were randomly filled with graft materials. One of the defects was left without any graft in all samples (as a control defect). The amount of bone formation was evaluated 3 months after surgery histopathologically. The data were analyzed using Friedman test, and when P-value was less than 0.05, the pair wise group comparison were performed by Wilcoxon (Boneferroni adjusted) test.

Results: Statistical analysis showed that there was a significant difference between bovine DBM group with control group (P=0.03). Furthermore, human DBM group was significantly different from control group (P=0.02). However, the difference between bovine DBM group and human DBM group was not statistically significant (P=0.87).

Conclusion: The results of this study showed the satisfactory bone healing in rabbit parietal bone defects filled with bovine DBM. The amount of healing in these defects was similar to bone defects which were filled with human DBM that is used clinically.

Background and Aims: There is not sufficient knowledge about the relationship between smoking and vertical bone loss in periodontal diseases. There are also important evidences which propose harmful effects of smoking on periodontal tissues including alveolar bone. The purpose of this study was to assess the relationship between smoking and prevalence and severity of vertical bone defects.
Materials and Methods: This case-control study consisted of 71 individuals with angular bone defects (case) and 69 individuals without angular bone defects (control) between 18 to 70 years old. People were selected by radiography, examining and filling up the questionnaire. Vertical bone defect was defined as interproximal bone resorption to the extent of ≥2mm with a clear angel towards the Mesial or Distal of root. Data were analyzed using SPSS software.
Result: The mean age of studied individuals was 37.14 years (±12.72). Among people with angular bone defects, 21.1% were light smokers and 25.4% were moderate-heavy smokers. There was a significant difference between smokers and nonsmokers in terms of smoking status and the chance of having angular bone defects (P=0.001). Simultaneous study of the effect of sex, age, brushing and smoking status showed that except sex, other variables have a significant effect on angular bone defects. The chance of having angular bone defects in light and heavy-moderate smokers was more than that in nonsmokers (adjusted OR=4.17 and adjusted OR=3.87, respectively).
Conclusion: These observations propose that smoking is related to increase in prevalence and severity of vertical bone defects. Smoking is considered as a potential risk factor for vertical periodontal bone loss.

Background and Aims: Nowadays reconstruction of alveolar defects has become one of dentists' problems especially in areas which are going to get dental implants. Inorganic bovine bone mineral (Bio-Oss) is one of the most popular graft materials that acts as a structure for migration of osteoblasts. If migration, proliferation, and differentiation of osteoblasts can be promoted by a material, it would be possible to reconstruct more amount of bone in a shorter period of time. Milk contains vital proteins that regulate bone growth. One of these important proteins is lactoferrin. The aim of this study was to examine the effect of added bovine lactoferrin to Bio-Oss on osteogenesis.
Materials and Methods: Two doses of 50 and 500 µg/ml of lactoferrin were prepared. Ten New Zealand white rabbits were selected for this study. Four 6-mm symmetrical detects were created in each rabbit's calvarium. Two of these sites were filled with Bio-Oss that was wetted with two doses of lactoferrin. Third detect was filled with Bio-Oss alone and the forth one was left empty as control group. After 4 weeks histologic and histomorphometric analysis was performed.
Result: There was no sign of obvious inflammation in any of four groups. Also there was no difference among four groups in terms of vitality, type of new bone, and foreign body reaction. However, amount of bone formation in control group was significantly lower compared with the other 3 groups. Although lactoferrin containing groups showed little increase in bone formation especially in higher concentration, there was not statistically significant difference among the three test groups. Amount of remaining biomaterial also was lower in lactoferrin containing groups compared with the Bio-Oss group but the differences were not significant.
Conclusion: Although there was no significant difference among the test groups, it seems that the added lactoferrin increases bone formation. Considering the limitations of this study, more studies are needed in different concentrations of lactoferrin and different healing periods. Furthermore, because of possible washout of the lactoferrin from the defects, it would be helpful to find and evaluate a proper carrier agent for lactoferrin to see its real effects.

Background and Aims: Accurate bone measurements are essential for determining the optimal size and length of proposed implants. The radiologist should be aware of the head position effects on image dimensions in each imaging technique. The purpose of this study was to evaluate the effect of mandibular plane angle on image dimensions in linear tomography.
Materials and Methods: In this in vitro study, the vertical dimensions of linear tomograms taken from 3 dry mandibles in different posteroantenior or mediolateral tilts were compared with actual condition. In order to evaluate the effects of head position in linear tomography, 16 series of images while mandibular plane angle was tilted with 5, 10, 15 and 20 degrees in anterior, posterior, medial, or lateral angulations as well as a series of standard images without any tilt in mandibular position were taken. Vertical distances between the alveolar crest and the superior border of the inferior alveolar canal were measured in posterior mandible and the vertical distances between the alveolar crest and inferior rim were measured in anterior mandible in 12 sites of tomograms. Each bone was then sectioned through the places marked with a radiopaque object. The radiographic values were compared with the real conditions. Repeat measure ANOVA was used to analyze the data.
Results: The findings of this study showed that there was significant statistical difference between standard position and 15º posteroanterior tilt (P<0.001). Also there was significant statistical difference between standard position and 10º lateral tilt (P<0.008), 15º tilt (P<0.001), and 20º upward tilt (P<0.001). In standard mandibular position with no tilt, the mean exact error was the same in all regions (0.22±0.19 mm) except the premolar region which the mean exact error was calculated as 0.44±0.19 mm. The most mean exact error among various postroanterior tilts was seen in 20º lower tilt in the canine region (1±0.88 mm) and for various mediolateral tilts the most exact error was seen in the canine region in 20º upper tilt (2.9±2 mm).
Conclusion: The mean exact errors in various regions and various 5º to 20º posteroanterior and mediolateral mandibular tilts were in the range of acceptable values (≤1 mm) except for the canine region. However, this effect is more considerable in mediolateral tilt compared with posteroanterior tilt, posterior region compared with anterior region, and upper tilt compared with lower tilt.

Background and Aims The purpose of this study was to evaluate the survival rate, mean bone loss and post operative complication of implants inserted in All-on-4 technique .

Materials and Methods: The literature was searched using keywords angled implant, All-on-4, tilted implant and graftless technique in the last 10 years (2001 to 2011) and clinical trial article that evaluated survival rate and mean bone loss around axial and tilted implants in All-on-4 technique was selected and evaluated.   A total of 73 articles were found by searching. After evaluation of titles and abstracts, finally 10 clinical trial, that were fully consistent with including criteria such as mean of bone loss and survival rate was selected and evaluated. 

Conclusion: Results showed that the survival rate (96-100%) and mean bone loss (0.34-1.9 mm) with All-on-4 technique in immediate loading is comparable with other implant support treatment plan. Comparison of implant survival and bone loss in axial and tilted implant in All-on-4 system is shown this treatment plan has consistent result with other conventional implant support prosthesis. Also, postoperative complication including fractures of the acrylic temporary prosthesis, detachment of the teeth, abutment or prosthesis screw loosening have been reported with All-on-4 technique. 

  Background and Aims: Hydroxyapatite coating has allocated a special place in dentistry due to its biocompatibility and bioactivity. The purpose of this study was to evaluate the relation between the hydroxyapatite thickness and stress distribution by using finite element method.

  Materials and Methods: In this paper, the effect of hydroxyapatite coating thickness on dental implants was studied using finite element method in the range between 0 to 200 microns. A 3D model including one section of mandible bone was modeled by a thick layer of cortical surrounding dense cancellous and a Nobel Biocare commercial brand dental implant was simulated and analyzed under static load in the Abaqus software.

  Results The diagram of maximum von Mises stress versus coating thickness was plotted for the cancellous and cortical bones in the range between 0 to 200 microns. The obtained results showed that the magnitude of maximum von Mises stress of bone decreased as the hydroxyapatite coating thickness increased. Also, the thickness of coating exhibited smoother stress distribution and milder variations of maximum von Mises stress in a range between 60 to 120 microns.

  Conclusion: In present study, the stress was decreased in the mandible bone where hydroxyapatite coating was used. This stress reduction leads to a faster stabilization and fixation of implant in the mandible bone. Using hydroxyapatite coating as a biocompatible and bioactive material could play an important role in bone formation of implant- bone interface.