The effect of housing environment on bone healing in a critical radius defect in New Zealand White rabbits.

In animal studies on bone healing, the effect of housing space and physical activity are seldom taken into account. Bone formation was evaluated in New Zealand White rabbits (mean ± SEM BW: 3.9 ± 0.11 kg) with a critical bone defect after 12 weeks of rehabilitation in pair-housing in 3 m2 large floor pens (Floor, n = 10) or standard single housing in 0.43 m2 cages (Cage, n = 10). In the randomised full-factorial study, a bone replica of calcium phosphate cement (CPC, n = 10) or autologous bone (AB, n = 10) was implanted in the unilateral 20 mm radius defect. Post-mortem, the oxidative capacity was measured by citrate synthase (CS) activity in M. quadriceps and the defect filling volume and density evaluated by microcomputer tomography (µ-CT). Histology sections were evaluated by subjective scoring and histomorphometry. Fourteen rabbits remained until the end of the study. Group Floor (n = 7; 3 CPC + 4 AB) had a higher CS activity and a larger bone defect filling volume and lower density by µ-CT measurements than group Cage (n = 7; 3 CPC + 4 AB). Three out of four rabbits in AB-Floor presented fusion of the defect with reorganisation of trabecular bone, whereas three of four in AB-Cage showed areas of incomplete healing. Floor rabbits had a higher score of bony fusion between the radius and ulna than Cage rabbits. There were no differences between groups in histomorphometry. The study found that a larger housing space increased physical activity and promoted bone formation.

Eight to eleven-year follow-up of immediately loaded implants placed in edentulous maxillae with compromised bone volume and poor bone quality: A prospective cohort study.

BACKGROUND: There is a lack of long-term evaluations of immediately loaded implants in patients with compromised maxillary bone. PURPOSE: To evaluate long-term survival and success of immediately loaded implants in subjects with poor maxillary bone quality and volume. MATERIAL AND METHODS: Follow-up was performed on subjects who received six implants loaded within 24 hours with screw-retained fixed prostheses. Twenty-five subjects with limited bone (Lekholm and Zarb, quantity 3 and 4, and quality C and D) were included in the study. Nineteen participated in the radiographic examination and of these 17 participated in the clinical examination at the last visit. Evaluations of marginal bone loss were performed at 1, 3, 5, and 8-11 years. The last clinical examination included removal of the prosthesis followed by registration of: plaque, pus, pocket depth, bleeding upon probing, mobility, and percussion testing. RESULTS: The mean follow-up was 9 years and 2 months (101-131 months) after surgery and showed a cumulative implant survival rate of 81.9% and success rate of 74.7%. Mean marginal bone loss was 1.29 mm (SD 2.47 mm range 0-11 mm) with a mean pocket depth of 3.1 mm (SD 2.4 mm, range 1.5-13.5 mm). 42.5% of the implants showed plaque retention and 72.2% showed bleeding on probing. CONCLUSION: This nonaugmenting immediate loaded implant protocol for maxillary edentulous patients is a satisfactory solution for selected patients.

A clinical and radiological long-term follow-up study of narrow diameter implants in the aesthetic area.

PURPOSE: To study long-term function of narrow diameter implants (NDI:s) and if reduced implant-tooth distance negatively impacts adjacent teeth. MATERIALS AND METHODS: A clinical and radiological follow-up of NDI:s replacing maxillary laterals and mandibular incisors was performed. Subjects that received 3.0-3.3 mm-diameter single implants from 3 units in Uppsala and Västerås, Sweden, between 2002 and 2011 were offered to participate in this retrospective study. RESULTS: Twenty-seven patients (30 implants) underwent clinical and CBCT examination, mean follow-up time was 63.3 months. On average, the implant-tooth distance was 1.6 mm at the cervical region and 17 implants were placed 1 mm or less to the adjacent root. Additionally, 2 patients (3 implants) underwent clinical examination (I). Twenty-seven patients (36 implants) declined the examination but agreed to an interview (II). At the time of the follow-up, all implants had good function, and implant survival of group I and II together was 97.2%. In both groups, the 2 main patient concerns were discoloration and regression of the buccal gingiva. CONCLUSION: Survival of implants is in accordance to standard diameter studies and although most implants were placed very close to the adjacent teeth, no pathologies could be linked to this except aesthetic concerns.

A new synthetic granular calcium phosphate compound induces new bone in a sinus lift rabbit model.

OBJECTIVES: The aim of this study was to investigate if a synthetic granular calcium phosphate compound (CPC) and a composite bisphosphonate-linked hyaluronic acid-calcium phosphate hydrogel (HABP·CaP) induced similar or more amount of bone as bovine mineral in a modified sinus lift rabbit model. MATERIAL AND METHODS: Eighteen adult male New Zeeland White rabbits, received randomly one of the two test materials on a random side of the face, and bovine mineral as control on the contralateral side. In a sinus lift, the sinus mucosa was elevated and a titanium mini-implant was placed in the alveolar bone. Augmentation material (CPC, HABP·CaP or bovine bone) was applied in the space around the implant. The rabbits were euthanized three months after surgery and qualitative and histomorphometric evaluation were conducted. Histomorphometric evaluation included three different regions of interest (ROIs) and the bone to implant contact on each installed implant. RESULTS: Qualitative assessment (p = <.05), histomorphometric evaluations (p = < .01), and implant incorporation (p = <.05) showed that CPC and bovine mineral induced similar amount of bone and more than the HABP·CaP hydrogel. CONCLUSION: CPC induced similar amount of bone as bovine mineral and both materials induced more bone than HABP·CaP hydrogel. CLINICAL SIGNIFICANCE: The CPC is suggested as a synthetic alternative for augmentations in the maxillofacial area.

Carprofen neither reduces postoperative facial expression scores in rabbits treated with buprenorphine nor alters long term bone formation after maxillary sinus grafting.

In connection with bilateral maxillary sinus augmentation, the acute effects of the nonsteroidal anti-inflammatory drug carprofen on facial expressions and long-term effects on bone formation were evaluated in 18 male New Zealand White rabbits. A 10×10mm bone window was drilled in the maxilla, the sinus membrane elevated and a titanium mini-implant inserted. One of two test materials was randomly inserted unilaterally and bovine bone chips (control) on the contralateral side in the created space. Rabbits were randomly allocated to receive buprenorphine plus carprofen (n=9) or buprenorphine plus saline (n=9) postoperatively. Buprenorphine was administered subcutaneously every 6h for 3days in a tapered dose (0.05-0.01mg/kg) and carprofen (5mg/kg) or saline administered subcutaneously 1h before, and daily for 4days postoperatively. To assess pain, clinical examination, body weight recording and scoring of facial expressions from photos taken before, and 6-13h after surgery were performed. Twelve weeks after surgery the rabbits were euthanized and sections of maxillary bones and sinuses were analysed with histomorphometry and by qualitative histology. Carprofen had no effect on mean facial expression scores, which increased from 0.0 to 3.6 (carprofen) and 4.3 (saline), of a maximum of 8.0. Neither did carprofen have an effect on bone formation or implant incorporation, whereas the test materials had. In conclusion, treatment with 5mg/kg carprofen once daily for 5days did not reduce facial expression scores after maxillary sinus augmentation in buprenorphine treated rabbits and did not affect long term bone formation.