Healing properties of implants inserted concomitantly with anorganic bovine bone. A histomorphometric human study

Hard and soft tissue healing around implants with Ag coating: An experimental study in dogs

Introduction The purpose of this randomized controlled canine experimental study was to evaluate peri‑implant hard and soft tissue healing around implants with silver coating. Methods All mandibular premolars and molars of five male beagle dogs were extracted. 25 test and 25 control implants were randomly installed and connected with the healing abutments. After 2 and 4 month healing period, implants with soft and hard tissues were obtained for histologic and histomorphometric analysis. Results In mesio-distal sections, supracrestal tissue attachment dimensions were 4.03±0.48 mm and 4.25±0.66 mm for test and 4.34±0.6 mm and 5.21±0.72 mm for control implants at 2 and 4 month healing time. The respective crestal bone loss values were 1.10±0.69 mm and 0.74±0.67 mm for test and 1.13±0.48 mm and 1.49±0.65 mm for control implants. The differences were statistically significant only in the 4-month healing period. In buccolingual sections, supracrestal tissue attachment height at 2 and 4 month healing periods were 4.09±0.64 mm and 4.5±0.8 mm for test implants and 4.17±0.76 mm and 4.48±0.76 mm for control implants. The respective mean values for crestal bone loss were 1.31±0.6 mm and 1.02±0.58 mm for test implants, and 1.28±0.61 mm and 1.29±0.69 mm for control implants. No statistical significant differences were recorded, apart from the height of connective tissue at the 2 month healing group. No significant difference in terms of BIC between implants or healing periods was recorded. Conclusions The Ag implant coating resulted in smaller supracrestal tissue attachment dimensions and less bone loss. Within the limits of a canine study, prevention of crestal bone loss along with the effectiveness of Ag antimicrobial properties in dental implantology is demonstrated.

Osseointegration Levels of Implants Placed With Allogenic and Xenogenic Bone Ring: An Experimental Biomechanical Analysis

This in vivo study aimed to do a biomechanical analysis of the early period bone-implant connection of titanium implants simultaneously inserted with xsenogenic and allogenic bone ring. In this study, 28 Sprague Dawley female rats were used. Four rats were killed to obtain an allogenic bone ring, and after this, the remaining rats were divided into control (n=8), xsenogenic (n=8), and allogenic (n=8) bone ring groups. Titanium-machined surfaced implants were integrated right tibias of the rats. In controls, only implants were integrated into right tibias. In the greft groups, the implants were integrated simultaneously with bone rings. After 2 weeks of the experimental period, the rats were killed ,and titanium implants and surrounding bone tissues were removed for biomechanic analysis. After biomechanical reverse torque analysis bone-implant connection was determined as Newton/cm2; in controls 3.26 (1.2 to 4.5), in allogenic ring group 3.37 (2 to 4.4), in xsenogenic ring group 5.93 (2.8 to 10). Statistically significant differences were not detected between the groups (P>0.05). Within the limitation of this study, both allogenic and xsenogenic bone grafts could be successfully used in bone augmentation in implant surgery.

Impact of Inorganic Xenograft on Bone Healing and Osseointegration: An Experimental Study in Rabbits

PURPOSE

To evaluate if an inorganic graft applied before implant insertion interferes with osseointegration.

MATERIALS AND METHODS

The bilateral mandibular incisors of 12 rabbits were extracted. One of the sockets was randomly filled with an inorganic xenogenic bone graft, whereas the remaining socket was allowed to heal naturally and served as a control. After 60 days, titanium implants were inserted into healing areas. The animals were killed 60 days after. Bone depositions were marked with fluorochrome oxytetracycline, alizarin, and calcein and evaluated using confocal laser scanning microscopy. Bone-to-implant contact (BIC) and bone area (BA) within the limits of the implant threads were analyzed. Data were compared statically by paired t tests, one-way ANOVA, and Bonferroni post hoc tests (α = 0.05).

RESULTS

No differences between the control and experimental groups in bone deposition for each marker, in either the BIC or BA analysis were observed. The bone deposition marked by alizarin (14-21 days) was the highest, followed by oxytetracycline (0 and 7 days) and calcein (45 and 52 days) in both groups (P < 0.05).

CONCLUSION

The bone healing or the course of osseointegration was not impaired by the use of an inorganic xenogenic graft before insertion of a titanium implant.

Histologic and Histomorphometric Comparison between Sintered Nanohydroxyapatite and Anorganic Bovine Xenograft in Maxillary Sinus Grafting: A Split-Mouth Randomized Controlled Clinical Trial

The presence of vital bone after maxillary sinus augmentation is crucial to enhance the quality of bone-implant interface, ensuring predictable long-term results. The aims of this RCT with split-mouth design were the histologic and histomorphometric comparison of two different biomaterials in sinus elevation after 6 months of healing and the evaluation of the clinical outcomes of implants inserted in the augmented areas after 12 months of prosthetic loading. Twenty-eight patients (10 females, 18 males) were treated with bilateral sinus floor elevation with lateral approach. Pure sintered nanohydroxyapatite (NHA) and anorganic bovine bone (ABB) were used as test and active control, respectively. After six months, 52 bone biopsies were harvested from 26 patients, and 107 implants were inserted in the augmented areas. Histomorphometry showed that, in the two groups, vital bone percentages were 34.9 ± 15% (NHA) and 38.5 ± 17% (ABB) (p = 0.428), marrow spaces percentages were 44.5 ± 18% (NHA) and 43.5 ± 23% (ABB) (p = 0.866), and residual graft percentages were 20.6 ± 13% (NHA) and 22.3 ± 12% (ABB) (p = 0.638). After 6 months of healing, no statistically significant difference was present in histomorphometric outcomes between NHA and ABB groups. Implant survival rate in NHA group after 12 months of loading was 96.4%, showing no statistically significant differences with ABB group.

Computerized histomorphometric study of the splenic collagen polymorphism: A control-tissue for polarization microscopy

Previous articles have pointed out the presence of type III collagen within the extracellular structure of the parenchymatous organs. This study aimed to quantitatively characterize the collagen polymorphism at the capsule and parenchymal trabeculae of the largest lymphoid organ of the body i.e., the spleen, in mouse, rat, and rabbit models. Following a Picrosirius Red-Polarization procedure and computer assisted image analysis of paraffin sections, the results showed (1) a predominant and significantly higher amount of type III collagen in the trabeculae area compared to the capsule area in the three species, (2) no statistical difference among the three species concerning the parenchymal collagen polymorphism or the type I/type III collagen ratio, (3) a heterogeneous type I/type III collagen ratio varying from 0.86 (mouse) to 6.62 (rabbit) in the fibromuscular capsule region. A qualitative analysis corroborated these histomorphometric results. In conclusion, the spleen may be used as (1) a control tissue to qualitatively visualize type I and III collagen under polarization microscopy and to validate the quality of PSR staining (2) an aid to accurately calibrate the angle of polarization before quantitative measurements of type I and type III collagen. Among the studied species, the rabbit spleen appeared to be the most appropriate control tissue as it showed the highest amount of type I collagen in the capsule and a similarly high amount of type III collagen in the parenchymal trabeculae.