Evaluation of Peri-implant Bone Stress on D1 Bone Using a Computerized Torque-Measuring Implant Motor: A Study on Photoelastic Resin Blocks.

PURPOSE: Recently, a torque-measuring micromotor that calculates the integral (I) of torque-depth curve at implant insertion was developed. This device was used to investigate the correlation between (I) and mechanical stress in photoelastic resin blocks with the density of D1 bone. MATERIALS AND METHODS: Using the micromotor, 40 implants (3.75 × 12 mm) were placed in 40 D1 blocks that had been prepared in four different ways. Four groups of 10 blocks each were prepared according to tunnel length (12 or 14 mm) and debris removal (yes or no). After insertion, peri-implant mechanical stress and its correlation with (I) were assessed by photoelastic and linear regression analysis, respectively. Analysis of variance (ANOVA) and Kruskal-Wallis tests investigated differences in mechanical stress patterns and dynamic parameters among the groups. RESULTS: (I) significantly correlated with mechanical stress in D1 resin under all conditions, except for 12-mm implant sites still containing debris. The correlation was significant concerning the whole dataset (r = 0.979) and separately for the coronal (r = 0.940), middle (r = 0.964), and apical (r = 0.948) portions of the implants. Peak torque did not correlate significantly with peri-implant mechanical stress. Longer implant sites and debris removal were significantly associated with lower peri-implant mechanical stress. CONCLUSION: (I) provides a reliable measure of mechanical stress in D1 bone during implant placement. Preparation of longer osteotomies and routine removal of all debris might reduce peri-implant bone stress significantly.

Mechanical properties of resin glass fiber-reinforced abutment in comparison to titanium abutment.

PURPOSE: So far, definitive implant abutments have been performed with high elastic modulus materials, which prevented any type of shock absorption of the chewing loads and as a consequence, the protection of the bone-fixture interface. This is particularly the case when the esthetic restorative material chosen is ceramic rather than composite resin. The adoption of an anisotropic abutment, characterized by an elastic deformability, could allow decreasing the impulse of chewing forces transmitted to the crestal bone. MATERIALS AND METHODS: According to research protocol, the mechanical resistance to cyclical load was evaluated in a tooth-colored fiber-reinforced abutment (TCFRA) prototype and compared to that of a titanium abutment (TA), thus eight TCFRAs and eight TAs were adhesively cemented on as many titanium implants. The swinging that the two types of abutments showed during the application of sinusoidal load was also analyzed. RESULTS: In the TA group, both fracture and deformation occurred in 12.5% of samples while debonding 62.5%. In the TCFRA group, only debonding was present in 37.5% of samples. In comparison to the TAs, the TCFRAs exhibited a greater swinging during the application of sinusoidal load. In the TA group, the extrusion prevailed, whereas in the TCFRA group, the intrusion was more frequent. CONCLUSION: The greater elasticity of TCFRA to the flexural load allows absorbing part of the transversal load applied on the fixture during the chewing function, thus reducing the stress on the bone-implant interface.

Hydraulic sinus lift technique in future site development: clinical and histomorphometric analysis of human biopsies.

PURPOSE: The fluid-dynamic technique is characterized by the hydraulic detachment of the mucosa and simultaneous filling of the sub-Schneiderian space, with a graft material of paste-like consistency. MATERIALS AND METHODS: Authors performed 13 future site developments, on as many patients (4 men; 9 women; age 49.46 ± 12.44 years), using a nanocrystalline hydroxyapatite dispersed in an aqueous matrix as graft material. In the second stage, performed at 5.96 ± 1.72 months, 13 implants were placed after harvesting bone biopsies from the regenerated sites. The above samples were subjected to histological and histomorphometric analysis. The histomorphometric results were then compared with the bone density, measured in Hounsfield units. RESULTS: The average percentage of vital bone was of 29.08% ± 14.7%, whereas the bone marrow and graft material were 59.75% ± 11.19% and 11.16% ± 10.88%, respectively. The percentage of vital bone has a significant correlation with the bone density of the recipient site (P = 0.003117). In contrast, the bone marrow (P = 0.08692) and the graft (P = 0.0799) do not show a significant correlation with this parameter. CONCLUSIONS: The results suggest the validity of the method in the regeneration of bone volume in the subantral region.

Maxillary sinus floor elevation via crestal approach: the evolution of the hydraulic pressure technique.

The current study describes an innovative protocol for the surgical maxillary sinus augmentation via a crestal approach that uses hydraulic pressure to lift the Schneiderian membrane and simultaneously fill the subantral space with a biomaterial for bone regeneration (nanocrystalline hydroxyapatite in aqueous solution). The technique in question combines the advantages of large amounts of grafted biomaterial with reduced trauma, high precision, and predictability.