Pilot Study In Dogs Research Articles

Can peri-surgical electroacupuncture relieve immunity suppression? A pilot study in dogs

General anesthesia and surgical stress can suppress the immunological response by acting both directly on the immune system and indirectly on the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. Disturbance of the immune system during the perioperative period can lead to complications such as wound-healing disorders and infections up to sepsis. Effectiveness of acupuncture in regulating the immune function by increasing leukocyte numbers and inhibiting inflammatory response has been proven. This study aimed to explore the impact of electroacupuncture (EAP) on the dynamic balance of the immune system and immune cell populations in dogs undergoing surgery. Twelve healthy bitches scheduled for elective ovariectomy were divided into two groups according to whether (EAP, n=6) or not (CTR, n=6) a peri-operative electroacupuncture treatment was performed. Levels of leukocytes (neutrophils, monocytes, T- and B-cells) and immunoglobulins M (IgM) and A (IgA) were measured in blood samples collected before (T0), 1 h (T1) and 2.5 h (T2) after anesthesia induction. Leukocytes count decreased from T0 to T1 in both groups and restored within 1.5 h in EAP group whereas remained significantly lower in CTR group (P<0.02). In particular, neutrophils and monocytes increased in dogs receiving EAP (P<0.01) while T-cells decreased in CTR group (P<0.04) at T2. B-cells and cytotoxic T-cells decreased in EAP dogs (P<0.04) at T2. No differences in helper T-cells, IgM and IgA levels were recorded between groups and over time. Our results suggest a modulatory effect of EAP on the immune system which is early expressed on neutrophils, monocytes and T-cells.

3Y-TZP/Ta Biocermet as a Dental Material: An Analysis of the In Vitro Adherence of Streptococcus Oralis Biofilm and an In Vivo Pilot Study in Dogs.

The surface adhesion of bacterial cells and the in vivo biocompatibility of a new ceramic-metal composite made of zirconium dioxide and tantalum were evaluated. Within the framework of an in vitro study using the crystal violet staining and colony counting methods, a relatively similar adhesion of Streptococcus oralis to the 3Y-TZP/Ta biocermet (roughness Ra = 0.12 ± 0.04 µm) and Ti-Al6-V4 titanium alloy (Ra = 0.04 ± 0.01 µm) was found. In addition, in an in vivo preliminary study focused on the histological analysis of a series of rods implanted in the jaws of beagle dogs for a six-month period, the absence of any fibrous tissue or inflammatory reaction at the interface between the implanted 3Y-TZP/Ta biocermets and the new bone was found. Thus, it can be concluded that the developed ceramic-metal biocomposite may be a promising new material for use in dentistry.

Kiosk 7R-FB-07 - Quantitative, Time-efficient Viability CMR with Delayed Phase Dynamic Contrast Enhancement MRI: A Pilot Study in Dogs with Acute Myocardial Infarction

Kiosk 7R-FB-07 - Quantitative, Time-efficient Viability CMR with Delayed Phase Dynamic Contrast Enhancement MRI: A Pilot Study in Dogs with Acute Myocardial Infarction

A Pilot, Open-Label Study to Evaluate the Efficacy of Intra-Articular Administration of a Caninized TNF Receptor Fc Fusion Protein as a Treatment for Osteoarthritis-Associated Joint Pain.

Tumor necrosis factor-α (TNF-α) is a potential target for osteoarthritis (OA) treatment. In several recent clinical studies in human OA, anti-TNF-α therapy showed promising results; however, these were open-label and based on patient-reported outcome measures. In this study, we developed a caninized TNF-α receptor-Fc (caTNFR-Fc) fusion protein and conducted a non-randomized, open-label, pilot study in dogs with OA using objectively measured ground reaction forces and activity. The aims of the study were to assess the efficacy of the intra-articular (IA) injection of the caTNFR-Fc fusion protein as a treatment for OA pain, and additionally to evaluate TNF concentrations in synovial fluid (SF) between joints with/without OA in dogs. Dogs (n = 12) with single-limb lameness due to single joint appendicular OA were recruited. All dogs received caTNFR-Fc fusion protein injection into the affected joint under sedation. Objective kinetic gait analysis using force plate was performed prior to (baseline), and at 14- and 28-days following treatment. Additionally, SF samples were collected from OA joints (n = 69) and non-OA joints (n = 79) in a different cohort of dogs and TNF-α were measured using enzyme-linked immunosorbent assay. No significant treatment effects on the limb use, activity, and the questionnaire were found. The concentration of TNF-α was significantly higher in OA joints than in healthy joints (p = 0.0019), but TNF-α was detected in only 10/69 OA samples. The IA injection of caTNFR-Fc fusion protein provided no benefit in terms of objective limb use and activity data in dogs with OA in this pilot study. Although the SF concentration of TNF-α was significantly higher in OA joints, few OA joints had measurable TNF-α. Collectively, the data indicate TNF-α may not be a good therapeutic target in canine OA.

Adding Two Antimicrobial Glasses to an Endodontic Sealer to Prevent Bacterial Root Canal Reinfection: An In Vivo Pilot Study in Dogs.

Current endodontic procedures continue to be unsuccessful for completely removing pathogens present inside the root canal system, which can lead to recurrent infections. In this study, we aimed to assess the antimicrobial capacity and tissue response of two inorganic bactericidal additives incorporated into a paste root canal sealer on contaminated root dentin in vivo. An experimental study was performed in 30 teeth of five Beagle dogs. After inducing microbiological contamination, root canal systems were treated by randomly incorporating one of two antimicrobial additives into a commercial epoxy-amine resin sealer (AH Plus), i.e., G3T glass-ceramic (n = 10) and ZnO-enriched glass (n = 10); 10 samples were randomized as a control group. After having sacrificed the animals, microbiological, radiological, and histological analyses were performed, which were complemented with an in vitro bactericidal test and characterization by field emission scanning electron microscopy. The tested groups demonstrated a non-significant microbiological reduction in the postmortem periapical index values between the control group and the bactericidal glass-ceramic group (p = 0.885), and between the control group and the ZnO-enriched glass group (p = 0.169). The histological results showed low values of inflammatory infiltrate, and a healing pattern characterized by fibrosis in 44.4% of the G3T glass-ceramic and 60.0% of ZnO-enriched glass. Bactericidal glassy additives incorporated in this root canal sealer are safe and effective in bacterial reduction.

Evaluation of the Effect of Cannabidiol on Naturally Occurring Osteoarthritis-Associated Pain: A Pilot Study in Dogs

The objective of this study was to provide preliminary data describing the safety and effect of cannabidiol (CBD) for symptom relief of canine osteoarthritis-associated pain in a clinical setting using objective outcome measures. Twenty-three client-owned dogs with naturally occurring osteoarthritis of appendicular joints completed this prospective, double-blinded, crossover, placebo-controlled study. Baseline data were acquired for 4 wk, followed by random allocation to either placebo or CBD treatment for 6 wk, followed by 6 wk with the opposite treatment. Outcome measures included objective gait analysis, activity counts (via accelerometry) and clinical metrology instruments. There were no differences noted between groups at any time point for any of the recorded outcome measures. Adverse events associated with CBD administration included elevation in liver enzymes (n = 14) and vomiting (n = 2).

Timing of force application on buccal tooth movement into bone-grafted alveolar defects: A pilot study in dogs

The aim of this pilot study was to evaluate the effect of the timing of postoperative orthodontic force application on bone remodeling during tooth movement into surgical alveolar defects with bone grafts in beagle dogs. Six beagle dogs underwent surgery for buccal dehiscence-type defects (width, 5mm; height, 6mm) on the distal root of maxillary second premolars bilaterally for 12 defects. After 1-month healing, bone-augmentation procedures were undertaken at the dehiscence defects. The second premolars were protracted buccally for 6weeks into the surgical sites immediately (F-0), at 4weeks (F-4), or 8weeks (F-8) after grafting. Orthodontic tooth movement was monitored using digital models. Remodeling of alveolar bone was evaluated by histology, histomorphometry, immunohistochemistry, microcomputed tomography, and fluorescence microscopy. Group F-0 showed significant expansion (mean, 2.42mm) and tipping (mean, 9.03°) after completing orthodontic tooth treatment. The vertical bone defect was significantly lower in groups F-4 and F-8 than that in group F-0 (mean, 2.1, 2.7, and 4.5mm, respectively). In group F-4, the formation of new bone and mineralization were significantly greater than those in groups F-0 and F-8 (P<0.05). Group F-4 showed a minimal amount of bone-material remnants. Immunohistochemistry showed the highest expression of collagen-1 and osteopontin in group F-4, followed by group F-8 and group F-0, which demonstrated high osteoblast activity and enhanced bone remodeling in group F-4. Orthodontic force application at 4weeks after an augmentation procedure provided the best functional stimulation for an alveolar bone graft. This strategy enhanced new-bone regeneration and degradation of bone substitutes and, eventually, promoted bone remodeling in the bone-grafted area.

Periodontal tissue regeneration after low-intensity pulsed ultrasound stimulation with or without intra-marrow perforation in two-wall intra-bony defects-A pilot study in dogs.

To evaluate the effects of low-intensity pulsed ultrasound (LIPUS) with/without intra-marrow perforation (IMP) on periodontal healing in two-wall intra-bony defects in dogs. Two-wall intra-bony defects (5mm wide, 5mm deep) were created at the distal and mesial aspects of mandibular premolars in four beagle dogs (four defects per dog). The 16 defects were divided into four treatment groups: IMP, LIPUS, IMP+LIPUS (IMP/LIPUS) and control (open flap debridement). The LIPUS and IMP/LIPUS sites received daily LIPUS exposure for 3weeks starting 1week after surgery. The animals were euthanized 4weeks after surgery for histologic evaluation. There was significantly greater new bone formation at LIPUS (2.93±0.74mm) and IMP/LIPUS (3.18±0.52mm) sites than at control sites (1.65±0.46mm). New bone area at LIPUS (6.36±2.28mm2 ) and IMP/LIPUS (6.13±1.25mm2 ) sites was significantly greater than that at control sites (2.15±1.75mm2 ). New cementum length at LIPUS sites (4.09±0.75mm) was significantly greater than that at control (2.29±1.02mm) and IMP (2.41±0.41mm) sites. No significant difference was observed between LIPUS and IMP/LIPUS sites in any histomorphometric parameter. These findings suggest that LIPUS effectively promotes periodontal regeneration in two-wall intra-bony defects in dogs.

Peri-implantitis at implants with different diameters: a pilot study in dogs

AimTo evaluate the progression of an induced peri-implantitis at implants with different diameters and the outcome of a corrective surgical debridement.MethodsThree months after the extraction of the mandibular premolars and first molars in six dogs, non-submerged narrow implants (3.3 mm in diameter) or standard implants (3.8 mm and 4.1 mm) were installed in the molar regions, bilaterally. After 3 months, peri-implantitis lesions were induced with ligatures and plaque accumulation for 3 months. Plaque accumulation was allowed for a further month after ligatures removal. A surgical mechanical decontamination of the surfaces was subsequently performed using gauzes soaked in saline and irrigation. Five months after, biopsies were retrieved and histological slides prepared. X-rays were taken at treatment and 5 months after.ResultsFourth months after peri-implantitis induction, 2.2 ± 1.0 mm at the standard implants and 3.2 ± 0.4 mm at the narrow implants were observed. Five months after treatment, a mean gain of marginal bone of 0.5 ± 0.6 mm was obtained at the standard implants and of 0.9 ± 0.4 at the narrow implants (p = 0.249). The vertical and horizontal defects were found partially closed. At the histological analysis, the coronal level of osseointegration after 5 months of healing was at 2.1 ± 0.8 mm at the standard implants, and 2.8 ± 0.3 mm at narrow implants (p = 0.116).ConclusionsIn conclusion, the narrow implants showed a tendency of a faster progression of the induced peri-implantitis compared to standard implants. The implant diameter did not influence the outcome of a surgical treatment of an induced peri-implantitis.

Microbiologic effect of two topical anti-infective treatments on ligature-induced peri-implantitis: A pilot study in dogs.

The aim of this split-mouth design pilot study in dogs was to assess microbiologic effects of two topical anti-infective treatment protocols on dental implants subjected to ligature-induced peri-implantitis, without use of systemic antibiotics. Eight adult Beagle dogs each received four dental implants in contralateral, edentulated, mandibular jaw quadrants. After 8 weeks, silk ligatures were installed, to be removed after another 8 weeks. After 6 additional weeks, induced peri-implantitis lesions were subjected to either antimicrobial photodynamic therapy (aPDT) or a topical tetracycline (TTC) hydrochloride (50 mg/mL) solution. Microbiologic samples were collected from the deepest proximal peri-implantitis site in each jaw quadrant before and after treatment. The samples were analyzed using DNA-DNA hybridization checkerboard technique. Peri-implantitis induction successfully produced lesions with microbiologic characteristics similar to those found in humans. Overall results showed effective bacterial count reductions for both protocols. aPDT demonstrated major reductions of the red complex, but no statistical differences between groups were observed when adjusted for multiple comparisons. aPDT and TTC successfully decontaminated infected implant surfaces. Implant decontamination with aPDT appears to be a viable alternative to TTC in the management of peri-implantitis infection.

Prevention of Periodontitis by the Addition of a Bactericidal Particulate Glass/Glass-Ceramic to a Dental Resin: A Pilot Study in Dogs

The aim of the study is to evaluate, in a ligature-induced periodontitis model, the efficacy of a commercially available dental resin containing different antimicrobial glass/glass-ceramic additions (0–26 wt.%). It has been proved that a 26 wt.% glass addition to a conventional dental resin matrix does not alter neither its workability nor its adhesion to the surface of teeth; however, it does confer notable antimicrobial properties when tested in vitro. Moreover, in vivo tests in Beagle dogs demonstrated the prevention of bone loss in ligature-induced plaque accumulation around teeth. Particularly, the glass-ceramic filler resin composite has shown excellent antimicrobial control since it displays the same bone loss as that of the negative control. The results obtained in the present investigation have shown that a conventional dental resin containing a fraction of glass/glass-ceramic (≥26 wt.%) can prevent periodontitis, which is considered to be a most serious dental disease.

Retraction.

Negri B, Calvo-Guirado JL, Ramírez-Fernández MP, Maté Sánchez-de Val J, Guardia J, Muñoz-Guzón F. Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part II: a pilot study in dogs. Clin Oral Impl Res. 2012;23: 236-244. The above article, published online on 5 September 2011 in Wiley Online Library (wileyonlinelibrary.com) and in Volume 23, pp. 236-244, has been retracted by agreement between the journal Editor in Chief, L Heitz-Mayfield, and John Wiley & Sons Ltd. The retraction has been agreed due to image discrepancies, resulting in unreliable data. Images in Figure 8 have been used in another publication representing different time points. Reference Negri B, Calvo-Guirado JL, Ramírez-Fernández MP, Maté Sánchez-de Val J, Guardia J, Muñoz-Guzón F. Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part II: a pilot study in dogs. Clin Oral Impl Res. 2012;23: 236-244. https://doi.org/10.1111/j.1600-0501.2011.02290.x.

Retraction

Negri B, Calvo-Guirado JL, Pardo-Zamora G, Ramírez-Fernández MP, Delgado-Ruíz RA, Muñoz-Guzón F. Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part I: a pilot study in dogs. Clin Oral Impl Res. 2012;23: 228-235. The above article, published online on 24 March 2011 in Wiley Online Library (wileyonlinelibrary.com) and in Volume 23, pp. 228-235, has been retracted by agreement between the journal Editor in Chief, L Heitz-Mayfield, and John Wiley & Sons Ltd. The retraction has been agreed due to image discrepancies, resulting in unreliable data. Images in Figure 6a have been used in another publication representing different time points. Reference Negri B, Calvo-Guirado JL, Pardo-Zamora G, Ramírez-Fernández MP, Delgado-Ruíz RA, Muñoz-Guzón F. Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part I: a pilot study in dogs. Clin Oral Impl Res. 2012;23: 228-235. https://doi.org/10.1111/j.1600-0501.2011.02158.x.

Oncolytic reovirus therapy: Pilot study in dogs with spontaneously occurring tumours.

Oncolytic virotherapy is a novel treatment involving replication-competent virus in the elimination of cancer. We have previously reported the oncolytic effects of reovirus in various canine cancer cell lines. This study aims to establish the safety profile of reovirus in dogs with spontaneously occurring tumours and to determine a recommended dosing regimen. Nineteen dogs with various tumours, mostly of advanced stages, were treated with reovirus, ranging from 1.0 × 108 to 5.0 × 109 TCID50 given as intratumour injection (IT) or intravenous infusion (IV) daily for up to 5 consecutive days in 1 or multiple treatment cycles. Adverse events (AEs) were graded according to the Veterinary Cooperative Oncology Group- Common Terminology Criteria for Adverse Events (VCOG-CTCAE) v1.1 guidelines. Viral shedding, neutralizing anti-reovirus antibody (NARA) production and immunohistochemical (IHC) detection of reovirus protein in the tumours were also assessed. AE was not observed in most dogs and events were limited to Grade I or II fever, vomiting, diarrhoea and inflammation of the injected tumour. No infectious virus was shed and all dogs had elevated NARA levels post-treatment. Although IHC results were only available in 6 dogs, 4 were detected positive for reovirus protein. In conclusion, reovirus is well-tolerated and can be given safely to tumour-bearing dogs according to the dosing regimen used in this study without significant concerns of viral shedding. Reovirus is also potentially effective in various types of canine tumours.

Vertical Osseodistraction with a New Intraosseous Alveolar Distractor Prototype for Dental Implant Rehabilitation: A Pilot Study in Dogs.

To evaluate in dogs a newly developed intraosseous alveolar distractor (Mozo-Grau Alveolar Distractor) for vertical bone augmentation to allow placement of dental implants. Four dogs had their posterior teeth removed, and sockets were left to heal for 20 weeks. The right and left sides of the posterior mandibles were randomly allocated, according to a split-mouth design, to receive either two distractors, distracting a 32-mm-long bone segment, or two distractors supporting one bony segment 20 mm long and one 8 mm long. Each side of the jaw was treated by a different operator. Eight days after placement, distractors were activated with one complete turn (corresponding to 0.75 mm of vertical distraction) per day for 8 days, followed by a latency period of 10 weeks. Distractors were removed, and seven dental implants of two randomly allocated designs were placed in each dog. Implants were submerged for 2 months, and the dogs were sacrificed. Outcome measures were: success of the augmentation procedure (defined as a vertical gain of at least 5 mm of bone), any complications, implant failure, bone-to-implant contact (BIC), and peri-implant marginal bone level changes. One dog was withdrawn because of a mandible fracture. Eight complications occurred, and six osseodistractors were lost, but no implant failed. Only two segments in one dog achieved a vertical bone gain of at least 5 mm. The mean radiographic vertical bone gain was 2.28 mm, whereas the mean histologic vertical bone gain was 3.16 mm. Histologically, all the implants were osseointegrated. The mean BIC for implants placed in new distracted bone was 34.78% ± 11.60% and 35.66% ± 8.84% for those placed in native bone. The mean peri-implant marginal bone level loss was 0.56 ± 0.54 mm. It is possible to achieve vertical augmentation using intraosseous alveolar distractors to allow successful implantation of dental implants; however, the technique still requires surgical refinements and a dedicated training of the surgeons before being applied to humans.

Performance of a New Al₂O₃/Ce-TZP Ceramic Nanocomposite Dental Implant: A Pilot Study in Dogs.

Although titanium remains as the prevalent material in dental implant manufacturing new zirconia-based materials that overcome the major drawbacks of the standard 3Y-yttria partially-stabilized zirconia (Y-TZP) are now emerging. In this study, a new ceramic nanocomposite made of alumina and ceria-stabilized TZP (ZCe-A) has been used to produce dental implants with the mechanic and topographic characteristics of a pilot implant design to evaluate bone and soft tissue integration in a dog model (n = 5). Histological cross-section analysis of the implanted ceramic fixations (n = 15) showed not only perfect biocompatibility, but also a high rate of osseous integration (defined as the percentage of bone to implant contact) and soft tissue attachment. This clinical success, in combination with the superior mechanical properties achieved by this Al2O3/Ce-TZP nanocomposite, may place this material as an improved alternative of traditional 3Y-TZP dental implants.

Root coverage using porcine collagen matrix with fibroblast growth factor-2: a pilot study in dogs.

The aim of this study was to evaluate the effect of fibroblast growth factor-2 (FGF-2) in combination with porcine collagen matrix (CM) for coverage of gingival recession defects in dogs. In five male mongrel dogs, labial gingival recession defects were surgically created in the lower-third incisors bilaterally. The defects were randomly assigned to the CM/FGF-2 group (experimental) or the CM-only group (control). Standardized clinical photographs and silicone impressions were taken at 4 and 16weeks of healing to calculate the remaining recession area. The dogs were euthanized after 16weeks for histometric analysis. At 4weeks, the recession area of the CM/FGF-2 group was significantly smaller than that of the CM-only group (2.55±0.66 and 4.92±1.05mm2 , respectively, p=0.023), However, no significant difference was observed at 16weeks. Histometrically, the amount of newly formed cementum was larger in the CM/FGF-2 group than in the CM-only group at 16weeks (1.55±0.44 and 0.88±0.51mm, respectively, p=0.024). The combination of CM/FGF-2 may enhance the early wound healing and may promote cementum formation to a higher extent compared to the use of CM alone.

Hyaluronic Acid Improves Bone Formation in Extraction Sockets With Chronic Pathology: A Pilot Study in Dogs.

Previous studies on ridge preservation focusing on fresh extraction sockets using graft materials for ridge preservation procedures have reported a delay in the tissue modeling and remodeling phases. The objective of this study is to evaluate the effect of hyaluronic acid (HA) on healing of infected sockets. Six beagle dogs were used in this study. Both mandibular third premolars were hemisected, and the distal roots were extracted. Subsequently, periodontal and endodontic lesions were induced at the remaining mesial root. After communication of the periodontal lesion, an endodontic periapical lesion was observed at 4 months, and the mesial roots of both the right and left sides were extracted. HA was applied into the socket of the test group, and no treatment was administered to the other group (control group). Three months after extraction of the mesial roots, the dogs were sacrificed, and histologic evaluations were performed. The sockets were filled by mineralized bone (47.80% ± 6.60%) and bone marrow (50.47% ± 6.38%) in the control group, whereas corresponding values were 63.29% ± 9.78% and 34.73% ± 8.97% for the test group, respectively. There was a statistically significant difference between the groups. Reversal lines and a copious lineup of osteoblasts were observed in the middle and apical parts of the sockets in the test group. An infected socket shows delayed healing of the socket wound, and HA, because of its osteoinductive, bacteriostatic, and anti-inflammatory properties, may improve bone formation and accelerate wound healing in infected sockets.

Effect of Ultraviolet Irradiation of the Implant Surface on Progression of Periimplantitis--A Pilot Study in Dogs.

The objective of this study was to investigate morphologically the progression of periimplantitis around an ultraviolet (UV)-light-irradiated implant in dogs. Pure titanium implants (3.3 mm in diameter and 8 mm long) were placed into dog jawbone bilaterally. Implants on one side were irradiated with UV light for 15 minutes using a photodevice immediately before placement (UV group), whereas those on the other side were not irradiated (non-UV group). Osseointegration was confirmed 90 days after implant placement by radiography. Experimental periimplantitis was induced by the application of dental floss over 90 days. Clinical and radiographic examination and micro-computed tomography (micro-CT) were performed after 90 and 180 days, and bone resorption was measured. The bone-implant interface in tissue sections was examined by light microscopy. Bone resorption around the UV-irradiated implant was less pronounced than around the non-UV-irradiated implant in the ligature-induced periimplantitis model. Tissue section images revealed no contact and partial destruction at the bone-implant interface. Within the limitations of this preliminary investigation, it is suggested that UV-light-irradiated implants suppress spontaneous progression of periimplantitis.

Application of rhBMP-2 loaded collagen membrane on the buccal plate for ridge preservation: a pilot study in dogs

Objective: The aim of this study was to determine the effect of multi-layer of a collagen membrane alone or loaded rhBMP-2 on the buccal plate for ridge preservation after tooth extraction. Material and methods: Following bilateral extraction of the maxillary 1st and 3rd premolars in five dogs, rhBMP-2 loaded collagen membrane was applied to the buccal plates at the 1st premolar and collagen membrane only was applied to the buccal plates at the 3rd premolar unilaterally. The collagen membranes applied in the experimental groups were piled into four layers. The corresponding sites of the contralateral side healed naturally. After 3months of healing, the animals were sacrificed. Radiographic and histologic analyses were performed. Results: There was no significant difference in the healing of extraction socket at both 1st and 3rd premolars. In microcomputed tomography, the widths of the residual ridge of the experimental groups were similar with the controls. Histologically, the experimental groups did not exhibit different pattern compared to the controls regardless of the addition of rhBMP-2. Conclusion: Layering of the collagen membrane with or without rhBMP-2 on the buccal plate failed to show the effectiveness in dimensional preservation of the extraction socket.