More marginal bone resorptions occurred after the third year of loading in implants placed 1 mm below bone level. However, the resorptions did not reach the implants thread. In the control group, the first bone implant contact was placed under the level of the first threads. Therefore, the present randomized clinical trial confirmed the hypothesis that placing platform-switching implants 1 mm below bone level reduced marginal bone loss. It can be noted that to reduce resorption, platform-switching implants should be placed below bone level.
The aim of the present study was to assess the systemic effect of thymoquinone (TQ) on bone healing by starting TQ administration, either 40 days before, or on the day of the surgical procedure and continuing during the healing period of 28 days. Eighteen experimental rats were divided into three groups and defects were created in their tibias. The following procedures were performed for each group: Control group (C): No systemic drug administration (n D 6); Test group 1 (T1): Systemic TQ was administered daily starting 40 days before creation of the defect and additionally during the post-operative healing period of 28 days (n D 6); Test group 2 (T2): Systemic TQ was administered daily after creation of the defect and during the healing period of 28 days (n D 6). Quantitative measurement for new bone formation, osteoblast lining and semi-quantitative measurement of capillary intensities were examined and statistically analysed. There was a significant increase in the ratio of new bone per total defect area and new bone trabeculae lined by active osteoblasts in both test groups (T1 and T2) compared to control group (p < 0.05). However the difference between T1 and T2 was not statistically significant. TQ-administered groups also showed an increase in capillary intensity in the defect area compared to the control group (p < 0.05). Systemic administration of TQ either starting 40 days before or on the day of surgery accelerated new bone formation in a rat model and can be advocated as an adjunct to expedite bone healing.
The aim of this study is to investigate the effect of doxycycline collagen sponge on bisphosphonate-related osteonecrosis of the jaw (BRONJ) and the level of serum biomarkers as an indicator of osteonecrosis. Twenty-four rats were divided into four groups. Animals in the control group were injected with saline and animals in Groups I, II and III were injected with zoledronate three times a week for eight weeks. After eight weeks, the following procedures were performed in each group. In Group I: extraction of maxillary first molar, in Group II: extraction of maxillary first molar and mucoperiosteal coverage was performed and in Group III: extraction of maxillary first molar and mucoperiosteal coverage with doxycycline collagen sponges was performed. At the end of 16 weeks, all animals were sacrificed. Serum collagen type I C-telopeptide (CTx), tartrate-resistant acid phosphatase (TRACP 5b) and alkaline phosphatase (ALP) levels' analysis, clinical examination, histological and histomorphometrical analysis were performed. As a result no significant difference in CTx, TRACP 5b and ALP levels was observed between groups. Complete mucosal healing was observed in all animals in the control group and 66.7% of animals in Group III. The necrotic bone area in Group III was significantly lower than the other groups (p < 0.01). Statistically significant difference was observed between groups in terms of detached osteoclast number (p < 0.01). In conclusion, local application of doxycycline could have a positive effect in reducing the risk of BRONJ in rats.
Purpose
This study was performed to evaluate the influence of local application of thymoquinone (TQ) on bone healing in experimental bone defects infected with
Porphyromonas gingivalis
(PG).
Methods
Forty-two female rats were randomly divided into 6 groups. A bone defect was created on the right tibia of all animals. The PG, PG/collagen membrane (COL) and PG/TQ/COL groups were infected with PG. In the COL and PG/COL groups, the defects were covered with a COL; in the TQ/COL and PG/TQ/COL groups, the defects were covered with a TQ-containing COL. After 28 days, all animals were sacrificed. Quantitative measurements of new bone formation and osteoblast lining, as well as semiquantitative measurements of capillary density and tissue response, were analyzed. Furthermore, the presence of bacterial infections in defect areas was evaluated.
Results
The new bone formation, osteoblast number, and capillary density were significantly higher in the TQ groups than in the control groups (
P
<0.001,
P
<0.001, and
P
<0.01, respectively). In a comparison between the TQ/COL group, with a TQ-containing COL (TQ/COL), and the PG
–
infected TQ-containing COL (PG/TQ/COL) group, the newly formed bone and capillary density were higher in the TQ/COL group (
P
<0.01). When the control group was compared to the PG, PG/COL, and PG/TQ/COL groups in terms of tissue response, the differences were statistically significant (
P
<0.001,
P
=0.02, and
P
=0.041, respectively). The intensity of the inflammatory cell reaction was higher in the PG, PG/COL, and PG/TQ/COL groups (
P
<0.05).
Conclusions
Within the limitations of this study, the local application of a TQ-containing COL positively affected bone healing even if the bone defects were infected. The results suggest that TQ increased angiogenesis and showed promise for accelerating bone defect healing. Further research is warranted to support these findings and reach more definitive conclusions.
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