Effects of combined use of recombinant human fibroblast growth factor-2 and ß-tricalcium phosphate on ridge preservation in dehiscence bone defects after tooth extraction: A split-mouth study in dogs.

BACKGROUND AND OBJECTIVE: Following tooth extraction, bone resorption is especially severe in cases complicated with buccal dehiscence bone defects. To minimize this, various bone graft materials have been used for alveolar ridge preservation. This study aimed to evaluate additional effects of the concomitant use of recombinant human fibroblast growth factor-2 (rhFGF-2) with ß-tricalcium phosphate (ß-TCP) on ridge preservation in a dehiscence defect model after tooth extraction in dogs. MATERIALS AND METHODS: The maxillary first premolars of six beagle dogs were extracted and dehiscence defects of 4 × 4 × 5 mm (mesio-distal width × bucco-palatal width × depth) were created. Bilateral defects were filled with ß-TCP combined with 0.3% (w/v) rhFGF-2 (test sites) or the scaffold alone (control sites). Twelve weeks post-surgery, histologic and histometric evaluations were performed. RESULTS: Morphological measurements using micro-computed tomography revealed a significantly greater bone volume at the test sites (48.9 ± 9.06 mm3 ) than at the control sites (38.8 ± 7.24 mm3 ). Horizontal widths of the alveolar ridge at the coronal and middle position at the test sites (2.18 ± 0.71 mm, 2.93 ± 0.53 mm) were significantly greater than those at the control sites (1.47 ± 0.41 mm, 2.36 ± 0.45 mm, respectively). Regarding the histological parameters, the occupation rate of mineralized bone in the original defects was slightly higher at the test sites (44.07 ± 10.19%) than that at the control site (41.15 ± 6.56%). CONCLUSIONS: These results indicate that the adjunct use of rhFGF-2 with ß-TCP is effective for alveolar ridge preservation in fresh extraction sockets with dehiscence defects.

Comparison between different isoelectric points of biodegradable gelatin sponges incorporating ß-tricalcium phosphate and recombinant human fibroblast growth factor-2 for ridge augmentation: A preclinical study of saddle-type defects in dogs.

BACKGROUND AND OBJECTIVE: It is well known that recombinant human fibroblast growth factor-2 (rhFGF-2) signaling plays an important role in tissue repair and regeneration. rhFGF-2 strongly binds to acidic gelatin via ionic linkages and is gradually released upon gelatin decomposition. On the other hand, the linkage between rhFGF-2 and basic gelatin is so weak that most rhFGF-2 is rapidly released from basic gelatin by simple desorption. Gelatin/ß-tricalcium phosphate (ß-TCP) sponges, which comprise 50 wt% gelatin and 50 wt% ß-TCP in a cross-linked structure, can release rhFGF-2 gradually owing to their electrical features. In a previous study, we reported that new bone height in the test group using rhFGF-2 with acidic gelatin/ß-TCP sponges was significantly greater than that in the control group using acidic gelatin/ß-TCP sponges alone in a ridge augmentation model in dogs. However, whether these results depend on controlled release by the gelatin/ß-TCP sponges remains controversial. In this study, we evaluated the effects of controlled release by comparing acidic and basic gelatin/ß-TCP sponges with different isoelectric points (IEP) on ridge augmentation in dogs. MATERIALS AND METHODS: Twelve weeks after extraction of the maxillary second and third incisors of six dogs, critically sized saddle-type defects (8 mm length × 4 mm depth) were surgically created bilaterally 2 mm from the mesial side of the canine. Acidic gelatin/ß-TCP sponges (IEP 5.0) soaked with 0.3% rhFGF-2 were applied to the defect in the acidic group, whereas basic gelatin/ß-TCP sponges (IEP 9.0) soaked with 0.3% rhFGF-2 were applied to the defect in the basic group. Twelve weeks after surgery, biopsy specimens were obtained and subjected to microcomputed tomography (micro-CT) and histological analyses. RESULTS: New bone area detected by micro-CT analysis was significantly smaller in the basic group than in the acidic group. New bone height calculated by histologic sections was significantly lower in the basic group than in the acidic group. The total tissue height was lower in the basic group than in the acidic group. However, the differences between both sites were not significant. CONCLUSIONS: These findings suggest that in ridge augmentation of saddle-type defects, controlled release of rhFGF-2 induces notably more alveolar bone formation than does short-term application of rhFGF-2.

Enamel matrix derivative in liquid form as adjunct to natural bovine bone grafting at buccal bone dehiscence defects at implant sites: An experimental study in beagle dogs.

OBJECTIVES: To evaluate the effect of enamel matrix derivative in liquid form (EMD-liquid) as adjunct to grafting with natural bovine bone (NBB), on new bone formation and osseointegration in buccal dehiscence defects at dental implants. MATERIAL AND METHODS: In six beagles, 3 months after extraction of the mandibular premolars and first molars. Three titanium implants (3.3 Ø × 8.0 mm) were inserted, and dehiscence-type defects (mesiodistal width 3 mm × 5 mm depth) were created on their buccal aspect. The defects were randomly assigned to one of the following three treatment groups: Group 1: NBB, Group 2: NBB/EMD-L, Group 3: Control. All sites were covered with a collagen membrane. Histomorphometric measurements were performed after 3 months of healing. RESULTS: New bone area, bone-to-implant contact (BIC), and first BIC (fBIC) in the NBB and NBB/EMD-L groups were significantly greater than in the control group (p < .05). Further, f-BIC was at a significantly more coronal position in the NBB + EMD-liquid group (0.4 ± 0.1 mm) compared with the NBB group (1.2 ± 0.2 mm). CONCLUSIONS: Natural bovine bone grafting enhances bone regeneration and osseointegration at implants with buccal bone dehiscences compared with no grafting, and adjunct use of EMD-liquid appears to further enhance bone formation and osseointegration.

Histological healing after nonsurgical periodontal treatment with enamel matrix derivatives in canine experimental periodontitis.

The histological outcomes after nonsurgical periodontal treatment with enamel matrix derivatives (EMD) remain controversial. The present study evaluated periodontal wound healing after scaling and root planing (SRP) with subgingival application of EMD for treatment of experimental periodontitis. Periodontal breakdown was induced by applying silk ligatures around mandibular third and fourth premolars of six beagle dogs until radiographic bone loss progressed to approximately half of the root length. Probing pocket depth (PPD) and clinical attachment level (CAL) were proximally measured 2 weeks after ligature removal (baseline). Mesial and distal surfaces of the experimental teeth were subjected to SRP and randomized using a split-mouth design to subgingival application of EMD (test) or normal saline (control). PPD and CAL were re-evaluated at 11 weeks. Animals were sacrificed at 12 weeks for histological analyses. No significant differences were observed in PPD and CAL between both groups at baseline and at 11 weeks. Histologically, test sites exhibited a greater amount of new cementum than that did the control sites (p < 0.01). Moreover, the control sites revealed increased epithelial downgrowth compared with the test sites: (p < 0.05). On the other hand, no intergroup differences were detected in terms of bone position, connective tissue attachment, gingival recession, and planed root length. This study suggested that EMD has an increased potential to support formation of new cementum with decreased epithelial downgrowth when used as an adjunct to nonsurgical periodontal treatment.

Ridge preservation of extraction sockets with buccal bone deficiency using poly lactide-co-glycolide coated ß-tricalcium phosphate bone grafts: An experimental study in dogs.

BACKGROUND: The alveolar ridge undergoes pronounced reduction in height and width following tooth extraction. This study aims to comparatively evaluate the potential for ridge preservation in extraction sockets with buccal bone deficiency of ß-tricalcium phosphate coated with poly lactide-co-glycolide (ß-TCP/PLGA) and conventional particulate ß-TCP. METHODS: In six beagles, maxillary first premolars were extracted after removal of their buccal bone plates. Standardized bone defects (4 [mesiodistal width] × 4 [buccopalatal width] × 5 [depth] mm) were created at the sites of extraction sockets and filled with ß-TCP/PLGA (test sites) or particulate ß-TCP (control sites). Microcomputed tomography, histologic, and histometric evaluations were performed 12 weeks post-surgery. RESULTS: The test sites exhibited a significantly greater bone volume than the control sites (25.7 ± 2.14 versus 16.0 ± 3.3 mm3 ), although no statistically significant difference was detected in bone material density (746.3 ± 23.9 versus 714.5 ± 37.0 g/cm3 , respectively). Relative to the control sites, the test sites exhibited significantly greater alveolar-ridge coronal (2.0 ± 0.4 versus 1.1 ± 0.3 mm) and middle (2.9 ± 0.2 versus 2.1 ± 0.3 mm) horizontal widths and proportions of woven bone (50.3 ± 8.1% versus 38.0 ± 5.2%) and bone marrow (17.7 ± 6.6% versus 9.7 ± 4.1%) but a significantly lower proportion of connective tissue (10.7 ± 4.5% versus 18.3 ± 5.7%). CONCLUSION: Within the limitations of this study, the moldable ß-TCP/PLGA graft appears to exhibit a greater potential than the conventional particulate ß-TCP graft for ridge preservation of extraction sockets with buccal bone deficiency.

The Effects of Ultraviolet Light-Emitting Diodes with Different Wavelengths on Periodontopathic Bacteria In Vitro.

Objective: The aim of this study was to examine effects of recently developed ultraviolet light-emitting diodes (UV LEDs) wavelengths on in vitro growth and gene expression of cultural periodontopathic bacteria, and on viability of experimental gingival fibroblasts. Materials and methods: Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, and Streptococcus oralis were irradiated by UV LEDs (265, 285, 310, 365, and 448 nm) at 600 mJ/cm2 and grown anaerobically in vitro. The colony forming units were counted after 1 week. Cell morphology was observed using a scanning electron microscope (SEM). Quantitative real-time polymerase chain reaction was performed to investigate gene expression changes by 310 nm irradiation. Viability of the irradiated human gingival fibroblasts was evaluated using WST-8 assay. Results: Both 265 and 285 nm resulted in the complete death of bacteria and fibroblasts, whereas 310 nm caused partial killing and suppression of bacterial growth and much less damage to the fibroblasts in vitro. Both 365 and 448 nm resulted in no significant change. SEM showed that P. gingivalis cells gradually degraded from day 2 or 3 and were severely destructed on day 5 for 265, 285, and 310 nm. The 310 nm irradiation transiently suppressed the transcripts of SOS response- and cell division-relative genes. Conclusions: Both 265 and 285 nm may induce powerful bactericidal effects and severe fibroblast phototoxicity, and 310 nm may induce partial killing or growth suppression of bacterial cells with much less fibroblast phototoxicity. UV lights may have potential for bacterial suppression, with situations dependent on wavelength, in periodontal and peri-implant therapy.