Journal of Oral Implantology Histomorphometric Analysis of Bone Regeneration Using a dual-layer of membranes (dPTFE placed over collagen) in fresh extraction sites:In Canine Model. --Manuscript Draft-Manuscript Number: AAID-JOI-D-13-00027R1 Full Title: Histomorphometric Analysis of Bone Regeneration Using a dual-layer of membranes (dPTFE placed over collagen) in fresh extraction sites:In Canine Model. Short Title: Histologic assessment of a novel socket grafting technique Article Type: Clinical Research Keywords: collagen membrane; high-density polytetrafluoroethylene membrane; histological analysis; ridge preservation. Corresponding Author: Khalid Al-Hezaimi, MSc King Saud University Riyadh, SAUDI ARABIA Corresponding Author Secondary Information: Corresponding Author's Institution: King Saud University Corresponding Author's Secondary Institution: First Author: Khalid Al-Hezaimi, MSc First Author Secondary Information: Order of Authors: Khalid Al-Hezaimi, MSc Giovanna Iezzi Ivan Rudek Abdullah Al-Daafas Khalid Al-Hamdan Abdulaziz Al-Rasheed Fawad Javed Adriano Piatelli Hom-Lay Wang Order of Authors Secondary Information: Abstract: Background: In untreated extraction sockets, buccal bone remodeling compromises the alveolar ridge width. The aim was to assess histologically the efficacy of using a dual-layer of membranes (high density poly-tertrafluoroethylene [dPTFE] placed over collagen) for ridge preservation (RP) in fresh extraction sites. Material and methods: Eight beagle dogs were used. Following endodontic treatment of mandibular bilateral second (P2)-, third (P3)- and fourth (P4) premolars, mandibular bilateral first premolars and distal roots of P2, P3 and P4 were extracted atraumatically. Animals were randomly divided into four treatment groups. Group-1: Control-no treatment; Group-2: allograft placed in alveolum and socket covered with dPTFE membrane; Group-3: allograft placed in alveolum, buccal plate overbuilt with allograft and socket covered with dPTFE membrane; Group-4: allograft placed in alveolum and covered with dual layer of membranes (dPTFE placed over collagen). No intent of primary closure was performed for all groups. After 16-weeks, animals were sacrificed and mandibular blocks were assessed histologically for buccolingual (BL) width of alveolar ridge, percentage of bone formation and marrow spaces and the remaining bone particles. Results: BL width of the alveolar ridge was significantly higher among sockets in Powered by Editorial Manager® and Preprint Manager® from Aries Systems Corporation Group-4 than those in Group-1 (P<0.05). Amount of newly-formed bone existing in each socket was higher among extraction sockets in Group-4 than those in Group-1, Group-2 and Group-3 (P<0.001). There was a significant difference in the percentage of bone marrow spaces between all groups (P<0.001). There was no significant difference in the number of non-resorbed bone particles between the groups. Conclusion: Using a dual layer of membrane was more effective in RP than conventional socket augmentation protocols. Powered by Editorial Manager® and Preprint Manager® from Aries Systems Corporation *Article File 1 Title: Histomorphometric Analysis of Bone Regeneration Using a dual-layer of membranes 2 (dPTFE placed over collagen) in fresh extraction sites: In Canine Model. 3 Authors: Khalid Al-Hezaimi, BDS, MSc, FRCD (C),1,2 Giovanna Iezzi, DDS, PhD,3 Ivan 4 Rudek, DDS,4 Abdullah Al-Daafas, BDS, MSc,5 Khalid Al-Hamdan, BDS, MSc,1,2 Abdulaziz 5 Al-Rasheed, BDS, MSc,1,2 Fawad Javed, BDS, PhD,1 Adriano Piattelli, DDS, PhD,6 Hom-Lay 6 Wang, DDS, PhD7 7 Affiliations: 8 1. Engineer Abdullah Bugshan Research Chair for Growth Factors and Bone Regeneration, 3D 9 Imaging and Biomechanical Lab., College of Applied Medical Sciences; King Saud University, 10 Riyadh, Saudi Arabia; 11 2. Department of Periodontics and Community Dentistry, King Saud University, Riyadh, Saudi 12 Arabia; 13 3. Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, 14 Chieti-Pescara, Italy; 15 4. Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, 16 Ann Arbor, MI, USA. 17 5. Dental Clinics, King Fahad Security Force College, Riyadh, Saudi Arabia. 18 6. Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, 19 Chieti-Pescara, Italy 1 20 7. Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, 21 Ann Arbor, MI, USA. 22 Running title: Histologic assessment of a novel socket grafting technique 23 Conflict of interest and financial disclosure: The authors declare that they have no conflicts of 24 interest and there was no external source of funding for the present study. 25 Corresponding author: Dr. Khalid Al-Hezaimi. Engineer Abdullah Bugshan Research Chair 26 for Growth Factors and Bone Regeneration, 3D Imaging and Biomechanical Lab., College of 27 Applied Medical Sciences; and Department of Periodontics and Community Dentistry, King 28 Saud University, P.O.Box 60169, Riyadh 11545, Saudi Arabia. E-mail: hezaimik16@gmail.com 29 Number of words (abstract): 249 Number of words (main text): 2694 30 Number of figures: 5 Number of tables: 1 31 Number of references: 29 32 Key words: Collagen membrane; high-density polytetrafluoroethylene membrane; histological 33 analysis; ridge preservation. 34 35 2 36 ABSTRACT 37 Background: In untreated extraction sockets, buccal bone remodeling compromises the alveolar 38 ridge width. The aim was to assess histologically the efficacy of using a dual-layer of membranes 39 (high density poly-tertrafluoroethylene [dPTFE] placed over collagen) for ridge preservation 40 (RP) in fresh extraction sites. 41 Material and methods: Eight beagle dogs were used. Following endodontic treatment of 42 mandibular bilateral second (P2)-, third (P3)- and fourth (P4) premolars, mandibular bilateral 43 first premolars and distal roots of P2, P3 and P4 were extracted atraumatically. Animals were 44 randomly divided into four treatment groups. Group-1: Control–no treatment; Group-2: allograft 45 placed in alveolum and socket covered with dPTFE membrane; Group-3: allograft placed in 46 alveolum, buccal plate overbuilt with allograft and socket covered with dPTFE membrane; 47 Group-4: allograft placed in alveolum and covered with dual layer of membranes (dPTFE placed 48 over collagen). No intent of primary closure was performed for all groups. After 16-weeks, 49 animals were sacrificed and mandibular blocks were assessed histologically for buccolingual 50 (BL) width of alveolar ridge, percentage of bone formation and marrow spaces and the 51 remaining bone particles. 52 Results: BL width of the alveolar ridge was significantly higher among sockets in Group-4 than 53 those in Group-1 (P<0.05). Amount of newly-formed bone existing in each socket was higher 54 among extraction sockets in Group-4 than those in Group-1, Group-2 and Group-3 (P<0.001). 55 There was a significant difference in the percentage of bone marrow spaces between all groups 56 (P<0.001). There was no significant difference in the number of non-resorbed bone particles 57 between the groups. 3 58 Conclusion: Using a dual layer of membrane was more effective in RP than conventional socket 59 augmentation protocols. 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 4 76 INTRODUCTION 77 Studies1-6 have reported that buccal process of alveolar bone is largely composed of 78 bundle bone (an immature bone supplied solely by ligaments and tendons) that makes it more 79 susceptible to undergo resorption following tooth extraction than the lingual/palatal process. It is 80 well-documented that extraction of multiple contiguous teeth is associated with a more extensive 81 buccal bone remodeling as compared to when a single tooth is extracted.4-6 In untreated 82 extraction sockets, buccal bone remodeling may compromise the alveolar ridge width and 83 complicate future oral rehabilitative procedures such as implant therapy.1-5 84 Various alveolar ridge preservation (RP) techniques have been proposed to minimize 85 post-extraction alveolar bone remodeling4, 7-9. Studies have proposed that overbuilding the buccal 86 plate with bone grafting materials minimizes post-extraction alveolar bone remodeling.10, 11 The 87 authors hypothesized that addition of excessive bone grafting material in the areas where bone 88 resorption is significant (such as buccal and coronal surfaces of the socket); helps compensate 89 the natural bone resorption phenomenon.10, 11 The results showed that buccal overbuilding with 90 excessive graft material is an ineffective technique for RP.10, 11. 91 Traditionally, collagen membranes are used in guided bone regeneration (GBR) protocols 92 due to their hemostatic, chemostatic and cell adhesive characteristics;12, 93 resorption rate following exposure to the oral environment has raised concerns over their usage 94 in GBR. However, it has been reported that collagen cross-linking increases its biodurability and 95 enables collagen-based membranes to support long-term osteogenic activity while preventing 96 other tissues from invading the defect.14, 97 successfully used in GBR 15 13 however, their fast Cross-linked collagen membranes have been procedures.16, 17 Advantages of using high-density 5 98 polytetrafluoroethylene (dPTFE) membranes in GBR are that they do not require primary 99 closure, are easy to remove without the need for additional surgical interventions and minimize 100 bacterial leakage;18-20 however, a limitation of dPTFE is that the membrane exhibits poor tissue 101 adhesive properties, which may sequentially jeopardize GBR.21 102 The present histologic study in dogs was based on the hypothesis that extraction sockets 103 treated with bone graft and covered with a dual-layer of membranes (dPTFE placed over a cross- 104 linked collagen membrane) show significantly higher percentage of trabecular bone and total 105 mineralized tissue as compared to those treated with conventional socket augmentation using 106 GBR concept. The aim of this histologic experiment was to assess the efficacy of using a dual- 107 layer membrane (dPTFE placed over collagen) for RP in fresh extraction sockets. 108 109 MATERIALS AND METHODS 110 Ethical guidelines 111 The study protocol was approved by the research ethics review committee of the Eng. A. 112 B. Research Chair for Growth Factors and Bone Regeneration, 3D Imaging and Biomechanical 113 Lab., College of Dentistry, King Saud University, Riyadh, Saudi Arabia. 114 115 Study animals 116 Eight healthy female beagle dogs were used. The mean age and weight of the animals 117 were 24±0.83 months and 13.8±0.49 kilograms (Kg) respectively. The animals were vaccinated 118 against hepatitis and rabies. 6 119 All non-surgical and surgical procedures were performed under general anesthesia (Pfizer 120 Limited, Sandwich, Kent, CT13 9NJ, UK) using ketamine (10 milligrams [mg] / Kg body- 121 weight) and local anesthesia (AstraZeneca LP for DENTSPLY Pharmaceutical, York PA) with 122 Xylocaine (with epinephrine 5 mg/millilitre). 123 124 Preoperative management 125 One week before tooth extraction, supragingival scaling was performed on all dogs using 126 an ultrasonic scaler (NSK, Westborough, MA). At the day of surgery, intra-muscular (IM) 127 injections of amoxicillin (25 mg/Kg body weight) (Betamox LA. Norbrook Laboratory Limited, 128 Newry, County Down, Northern Ireland) were administered. The animals were draped and the 129 surgical site was swabbed with an antiseptic solution (The Purdue Fredrick Company, Stamford, 130 CT, USA). 131 132 Root canal treatment and tooth extractions 133 All surgical and non-surgical procedures were performed under general anesthesia using 134 intramuscular injections of keramine (Pfizer Limited, Sandwich, Kent, CT13 9NJ, UK) with 135 adjunct buccal infiltration of local anesthesia (AstraZeneca LP for DENTSPLY Pharmaceutical, 136 York PA, USA). Non-surgical root canal treatment (RCT) was performed on bilateral 137 mandibular second (P2), third (P3) and fourth premolars (P4). A No. 2 size round tungsten bur 138 (Brassler, Savannah, GA, USA) mounted on a high-speed hand piece (Dentsply, York, PA, 139 USA) was used to prepare the access cavity. Initial instrumentation of the root-canals was 140 performed with K-type hand files (JS Dental, Ridgefield, CT, USA) following which rotary files 7 141 (Profile, Dentsply, Addlestone, UK) were used for final root-canal preparation. The root-canals 142 were irrigated with 5.25% sodium hypochlorite and obturated with vertically condensed gutta 143 percha and sealer (Pulp Canal Sealer EWT, SybronEndo, Orange, CA, USA). Accuracy of root- 144 canal length was verified by an apex locator (J. Morita USA, Inc.: Root ZX II- Apex Locator, 145 Irvine, CA, USA) and periapical radiographs. Teeth with periapical lesions such as periapical 146 granuloma were excluded. 147 After two months of RCT, none of the teeth showed signs of periapical pathosis. bilateral 148 mandibular first premolars (P1) were extracted atraumatically. Bilateral mandibular P2, P3 and 149 P4 were hemisected using piezosurgery (Mectron, Piezosurgery® Columbus, Ohio, USA) and 150 the distal roots were atraumatically extracted using forceps. The distal alveolus was currettaged 151 to stimulate bleeding and eliminate remnants of the periodontal ligaments. 152 153 Animal grouping 154 Randomization was performed by picking a paper marked either "Group 1", "Group 2", 155 "Group 3" or "Group 4" from a brown bag. Group 1 (Control-group), comprised of an untreated 156 extraction socket. In Group 2, particulate graft (Zimmer ׀Dental, Puros® cancellous particulate 157 allograft, Carlsbad, CA, USA) was placed in the socket and covered with dPTFE membrane 158 (Cytoplast® Barrier Membranes, TXT-200, Lubbock, TX, USA). In Group 3, particulate graft 159 (Zimmer ׀Dental, Puros® cancellous particulate graft, Carlsbad, CA, USA) was placed in the 160 socket, buccal plate was overbuilt with excess particulate graft and the socket was covered with 161 dPTFE membrane (Cytoplast® Barrier Membranes, TXT-200, Lubbock, TX, USA). In Group 4, 162 particulate graft (Zimmer ׀Dental, Puros® cancellous particulate graft, Carlsbad, CA, USA) was 8 163 placed in the alveolum and covered with a “dual-layer” of membranes (that is, a dPTFE 164 membrane [Cytoplast® Barrier Membranes, TXT-200, Lubbock, TX] placed over a collagen 165 membrane [Cytoplast® RTM Collagen, Osteogenics Biomedical, Inc. Germany]). In all groups, 166 primary closure was not intended (Ethicon Inc. VICRYL [Polyglactin 910] suture, Somerville, 167 NJ) (Figure 1). 168 169 Postoperative management and euthanasia 170 All subjects received IM injections of amoxicillin (Betamox LA. Norbrook Laboratory 171 Limited, Newry, County Down, Northern Ireland) (5mg/Kg body weight once a day for 3 days). 172 Plaque control procedures, which included topical application of a 0.2% chlorhexidine 173 digluconate solution (GUM, Chicago, IL, USA) were performed twice a week for four months 174 after surgery. IM antibiotics (Betamox LA. Norbrook Laboratory Limited, Newry, County 175 Down, Northern Ireland) were continued for three days after surgery as 25-50 mg/Kg IM every 8 176 hours. 177 178 After 4-months, all subjects were sacrificed using an overdose of 3% sodium pentobarbitol (Vortech Pharmaceuticals Limited, Dearborn, MI, USA). 179 180 181 Jaw sectioning, measurement of vertical bone height and buccolingual width 182 The jaw segments containing the extraction sockets were removed en block using an 183 electric saw (Leica SP 1600, Bannockburn, IL, USA); and fixed in 10% neutral formalin 184 solution. 9 185 186 187 Histologic analysis 188 The samples and surrounding tissues were washed in saline solution and were 189 immediately fixed in 4% paraformaldehyde and 0.1% glutaraldehyde in 0.15 mol/L cacodylate 190 buffer at 4°C and pH 7.4, to be processed for histology. The specimens were processed to obtain 191 thin ground sections and were dehydrated in ascending series of alcohol rinses and were 192 embedded in a glycol (methyl methacrylate) resin. After polymerization, the specimens were 193 sectioned with a high-precision diamond disk at about 150 mm and were ground to about 30 mm. 194 The slides were stained with acid fuchsin and toluidine blue as described earlier.22 The following 195 descriptive parameters were measured by one examiner (GI): (a) Buccolingual (BL) width of the 196 alveolar ridge was defined as the distance from the most outer point of the buccal bone plate to 197 the most outer point of the lingual bone plate. The measurement was taken at 2mm perpendicular 198 from the CEJ and in the middle of the socket; (b) Percentage of bone/socket; (C) Percentage of 199 bone marrow spaces and (d) Percentage of non-resorbed bone particles. The measurements were 200 performed with a microscope linked to a video camera (Buehler, New jersey, USA) /computer 201 (Buehler, New jersey, USA) and software (Buehler, New jersey, USA). 202 203 Statistical analysis 204 Statistical analysis was performed using a statistical software (SPSS, Version 18.00, 205 Chicago, IL, USA). The descriptive analyses of each histomorphometric parameter in each dog 206 was obtained after analyzing three sections per site, 50 µm apart for each position. Significance 207 differences among the groups were determined using one-way analysis of variance. For multiple 10 208 comparisons Bonferroni post hoc test was used. P-values less than 0.05 were considered 209 statistically significant. 210 211 RESULTS 212 213 1-Alveolar ridge width 214 The BL widths of the alveolar ridge in Group-1, 2, 3 and 4 were 5.27±1.22 mm, 215 5.81±1.11 mm, 6.41±0.99 mm and 6.64±1.64 mm respectively. The BL width of the alveolar 216 ridge was significantly higher among sockets in Group-4 (6.64±1.64 mm) as compared to those 217 in Group-1 (5.27±1.22 mm) (P<0.05). 218 219 2-Percentage of bone formation/socket 220 The amount of bone existed in each socket was significantly higher among extraction 221 sockets in Group-4 (92.5±10.4%) as compared to those in Group-1 (34±19.35%) (P<0.001), 222 Group-2 (43±29.41%) (P<0.001) and Group-3 (56.5±25.01%) (P<0.001). These results are 223 shown in Table 1. 224 225 3- Bone marrow space percentage 226 The percentage of bone marrow spaces in Groups 1, 2, 3 and 4 were 54.4217.97%, 227 50.64 26.51%, 35.64 22.7% and 7.510.40% respectively. The difference was significance 11 228 between all the groups (P<0.001). 229 230 4- Percentage of non-resorbed bone particles 231 The remaining non-resorbed bone particles were counted and calculated per socket. Since 232 the first group had no bone graft material, it was not included. The remaining particles for groups 233 2, 3 and 4 were 13.0 4.2%, 14.8 4.49% and 10.5 3.34% respectively. There was no 234 significance difference between the groups (P<0.633). 235 236 Histological analysis 237 In Group-1 (at 10X), mandibular cortical bone surrounded by oral mucosa was observed 238 in the area of the first premolar tooth with periodontal ligament surrounding the apical portion of 239 the canine. Mature compact bone with large amounts of osteons can be observed (Figure 2a and 240 2b). 241 In Group-2, osteons cells and cortical bone with mature compact and trabecular bone can 242 be seen (Figure 3a). At 40X magnification, particulate graft, compact and mature bone was 243 evident on the buccal surface was observed with newly formed bone with small marrow spaces 244 (Figure 3b). At 40X magnification, newly formed bone with small marrow spaces and cement 245 lines can be observed between pre-existing bone and newly formed bone 246 same magnification (40X) no residual particles of biomaterial can be detected inside the bone 247 defect (Figure 3d). 248 (Figure 3c). At the In Group-3, cortical, compact and mature bone were observed with fibrointegrated 12 249 residual particulate graft particles next to oral mucosa (Figure 4a-4c). At 100X magnification, 250 fibrointegrated particulate graft particles with dense connective tissue in tight contact with 251 particulate graft were observed (Figure 4d-4f). At 40X magnification, newly formed bone with 252 small marrow spaces can be observed. Cement lines can be observed between pre-existing bone 253 and newly formed bone (Figure 4a-4f). 254 In Group-4, at 10X magnification (Figure 5a), large amount of trabecular bone were 255 observed in the socket site. At 40X magnification, significant mature remodeled bone where the 256 areas of remodeling can be observed (Figure 5b). At higher magnification where evidence of 257 remaining particles and evidence of modeling and remodeling was taking place (Figure 5c and 258 5d). At another view, it can be seen the bonding between the newly formed bone and native 259 bone (Figure 5e and 5f). 260 261 DISCUSSION 262 The present histologic results showed that RP (in fresh extraction sites) using a dual-layer 263 of membranes (dPTFE placed over collagen membrane) enhances BL width of the alveolar ridge 264 as compared to when regenerative protocols were performed using either a single layer of 265 membrane or without a barrier membrane. In addition, the present experimental histologic results 266 also demonstrated that the amount of new bone formed in extraction sockets in Group-4 was 267 significantly higher than that formed in Groups 1, 2 and 3 and that the number of non-resorbed 268 bone particles were significantly less among extraction sockets in Group-4 as compared to those 269 in Groups 2, 3 and 4. Furthermore, scanning electron microscopy (SEM) results by Yun et al. 270 (2011) showed that a dual layer of membrane (dPTFE placed over collagen membrane) is an 13 271 effective way for RP around immediate implants. Various explanations may be posed in this 272 regard. Firstly, since collagen- and dPTFE membranes exhibit advantageous properties (such as 273 optimal behavior toward soft-tissue responses and optimal durability respectively); it is 274 postulated that using these membranes (collagen and dPTFE) as a dual-layer further augments 275 new bone formation then when each membrane type is used individually. Next, it may also be 276 proposed that placement of a dPTFE augments new bone formation by stabilizing the graft at the 277 defect site/s. Moreover, bacterial count has been reported to be significantly lower on the inner 278 aspect of the dPTFE membrane as compared to the outer surface (Yun et al. 2011). This suggests 279 that the dPTFE membrane provides a reasonably bacteria-free environment to the underlying 280 collagen membrane that may in turn facilitate its chemostatic and cell adhesive properties. The 281 present histologic study supports the SEM results reported by Yun et al. (2011). However, 282 further studies are warranted to identify the microbial species that may be associated with 283 extraction barrier membranes placed in fresh extraction sites. 284 Various bone grafting materials with different densities are used in RP procedures. 23-25 It 285 is hypothesized that bone mineral density of the bone graft material used during RP protocols 286 may influence the overall outcome of the procedure. In the present experiment, a standardized 287 bone particulate graft was used in all extraction sockets; which reflects that the outcome was 288 chiefly associated with the dual-layer technique and not the type of particulate graft used. An 289 interesting finding in the present experiment was that the percentage of non-resorbed bone 290 particles was significantly less in extraction sockets belonging to Group-4 as compared to 291 Groups 2, 3 and 4. A possible explanation that may be proposed in this regard is that placement 292 of a dual-layer of membrane helps stack the bone minerals in the region of interest thereby 293 preventing dispersion of the bone matrix. This may in turn have helped augment the undergoing 14 294 bone regeneration as compared to other groups where early resorption as well as collapse of 295 collagen membrane may have been liable for reduced bone formation and demonstrating 296 increased number of non-resorbed bone mineral particles. 297 Tissue biotypes have been associated with the outcomes of periodontal surgical 298 interventions.26-28 Thin soft tissue biotypes have been associated with thinner underlying alveolar 299 bone and angular bone defects as compared to thick soft tissue biotypes.26,27 In a recent clinical 300 study, Le et al.27 investigated the relationship between buccal/labial bone thickness and crestal 301 labial soft tissue thickness around dental implants. The results demonstrated a significant 302 relationship between the amount of buccal bone and thickness of soft tissues. Since canine 303 models exhibit a thin periodontal tissue biotype, it is tempting to speculate that the outcomes of 304 bone regenerative protocols may also be compromised compared to those performed in clinical 305 scenarios. However, further studies are warranted in this regard. 306 It is pertinent to mention that there are a few limitations of the present experiment. It is 307 noteworthy that in the present experiment, all walls of the extraction sockets were intact. It is 308 therefore hypothesized that presence of an osseous defect or a pathological lesion within or 309 around the extraction socket may jeopardize new bone formation. Likewise, clinical studies29-32 310 have shown that systemic disease (such as poorly-controlled diabetes mellitus and acquired 311 immune deficiency syndrome) and tobacco habits (such as cigarette smoking and tobacco 312 chewing) jeopardize the alveolar bone and also negatively influence the outcome of periodontal 313 therapy. It is tempting to speculate that the efficacy of novel RP techniques (such as those 314 described in the present study) may be compromised in immunocompromised individuals and in 315 tobacco-smokers. It has also been reported that the severity of periodontal disease increases with 316 advancing age.26 It may therefore be argued that the outcomes of ridge preservative techniques in 15 317 elderly individuals may be compromised as compared to those in younger patients. However, 318 further studies are required in this regard. 319 320 321 CONCLUSION 322 Within the limits of the present histologic investigation, it is concluded that ridge 323 preservation using a dual layer of membrane following tooth extraction enhances the alveolar 324 ridge width as compared to when a single layer of membrane is used. 325 326 327 328 Acknowledgement This study is registered at the College of Dentistry Research Center (CDRC No: FR 0026), King Saud University, Riyadh, Saudi Arabia. 329 330 331 332 333 334 335 336 16 337 FIGURE LEGENDS 338 Figure 1. Clinical and radiographic pictures of the treatment protocol 339 (a) Preoperative clinical photograph. (b) Distal roots were hemisectioned and extracted with no 340 dehiscence. (c) A measuring surgical stent was fabricated to ensure repeat measurements 341 overtime. (d) Shows the different sites with application of membrane alone, membrane and bone 342 graft, dual-layer membrane, and bone graft material. (e) Primary closure was achieved. (f) 343 Radiograph showing endodontically treated distal roots filled with gutta percha. 344 345 Figure 2. Histologic evaluation of extraction sockets in Group-1 (no treatment group) using 346 Toluidine blue acid fuchsin. 347 (a) Mandibular cortical bone surrounded by oral mucosa in the area of the first premolar tooth. 348 The apex of the canine root surrounded by periodontal ligament can also be seen at 10X 349 magnification. (b) At 40X magnification, mature compact bone with osteons (Arrow). Fibrous 350 connective tissue of oral mucosa (Arrow head). 351 352 Figure 3. Histologic evaluation of extraction sockets in Group-2 (particulate graft placed in 353 alveolum and socket covered with a high density polytetrafluoroethylene membrane) using 354 Toluidine blue acid fuchsin. 355 (a) At 10X magnification, cortical bone with mature compact bone can be seen. Inside the 356 section trabecular bone can also be observed. 357 mature bone belonging to the external portion of the jaw (Arrow). 358 particulate graft surrounded by connective tissue both located outside the defect (Arrow head). 359 (c) At 100X magnification, newly formed bone with small marrow spaces and cement lines can (b) At 40X magnification, cortical, compact, At 40X magnification, 17 360 be observed between pre-existing bone and newly formed bone (Arrow). At 100X magnification, 361 connective tissue in close proximity to newly formed bone (Arrow head). 362 magnification, mature bone tissue can be observed (Arrow) with no residual particles of 363 particulate graft inside the bone defect. At 40X magnification, newly formed bone in tight 364 contact to pre-existing bone can be observed (Arrow heads). (d) At 40X 365 366 Figure 4. Histologic evaluation using Toluidine blue acid fuchsin of extraction sockets in Group- 367 3 (particulate graft placed in alveolum, buccal plate overbuilt with particulate graft and socket 368 covered with a high density polytetrafluoroethylene membrane). 369 370 (a) At 10X magnification, cortical, compact and mature bone can be observed with 371 fibrointegrated residual particulate graft particles next to oral mucosa. In the central portion of 372 the sample trabecular bone can be observed in the central portion. (b) At 40X magnification, a 373 small marrow space inside the cortical bone can be observed (Arrow) with particulate graft 374 particles surrounded by fibrous tissue (Arrowhead). (c) At 40X magnification, preexisting bone 375 (Arrow) and newly-formed bone (Arrowhead) can be observed. (d) At 40X magnification, 376 cortical bone (Arrow) and fibrointegrated residual particulate graft particles, located outside the 377 defect can be observed (Arrow head). (e) At 100X magnification, fibrointegrated particulate graft 378 particles (Arrow head) with dense connective tissue in tight contact with particulate graft can be 379 observed. (f) At 100X magnification, dense connective tissue (Arrow) and particulate graft 380 particles (Arrow Head) can be seen. 381 18 382 Figure 5. Histologic evaluation using Toluidine blue acid fuchsin of extraction sockets in Group- 383 4 (particulate graft placed in alveolum and covered with a dual-layer of membrane [high density 384 polytetrafluoroethylene membrane placed over a collagen membrane]). 385 386 (a) At 10X magnification, Trabecular bone can be observed in the area where defect was 387 induced. (b) At 10X magnification, bone trabeculae in the medullary portion of the section can 388 be observed. (c) At 100X magnification, particulate graft particles surrounded by connective 389 tissue can be seen. (d) At 40X magnification, newly formed bone in tight contact to pre-existing 390 bone (Arrow) with fibrointegrated particulate graft can be observed (Arrow Head). (e) Arrow: At 391 40X magnification, mature bone with areas of remodeling can be observed (Arrow) with 392 fibrointegrated particulate graft particles inside the defect (Arrow Head). (f) Bonding between 393 the newly formed bone and native. 394 395 396 397 398 399 400 401 19 402 REFERENCES 403 1. Moura FC, Araujo MH, Costa RC, et al. Efficient use of Fe metal as an electron transfer 404 agent in a heterogeneous Fenton system based on Fe0/Fe3O4 composites. Chemosphere. 405 2005;60:1118-1123. 406 2. Al-Askar M, O'Neill R, Stark PC, Griffin T, Javed F, Al-Hezaimi K. Effect of Single and 407 Contiguous Teeth Extractions on Alveolar Bone Remodeling: A Study in Dogs. Clin 408 Implant Dent Relat Res. 2011; Dec 15. doi: 10.1111/j.1708-8208.2011.00403.x. [Epub 409 ahead of print] 410 3. 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Group-1 Group-2 (mean±SD) (mean±SD) Group-3 Group-43 (mean±SD) (mean±SD) 4 8 Percentage of bone formation/socket 34±19.35 Buccolingual width (mm) 5.27±1.22 * P<0.001 43±29.41 * 56.5±25.01† 92.5±10.4† 6.41±0.99 6.64±1.646 * † P<0.001 5.81±1.11 ‡ ‡ P<0.05 mm: millimeters 5 7 SD: Standard deviation 9 10 1 Figure Click here to download high resolution image Figure Click here to download high resolution image Figure Click here to download high resolution image Figure Click here to download high resolution image Figure Click here to download high resolution image Copyright Form Click here to download Copyright Form: ORIM TransferOfCopyright (KAH & FJ).pdf
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