The relationship between the bone characters obtained by CBCT and primary stability of the implants

Assessment of the Impact of Bone Quality and Abutment Configuration on the Fatigue Performance of Dental Implant Systems Using Finite Element Analysis (FEA)

BACKGROUND AND OBJECTIVES

The aim of this study was to evaluate the influence of abutment angulation, types, and bone quality on fatigue performance in dental implant systems.

MATERIALS AND METHODS

Three-dimensional models of maxillary 3-unit fixed implant-supported prostheses were analyzed. Abutments with different angles and types were used. Healthy bone (Hb) and resorbed bone (Rb) were used. Conducted on implants, a force of 150 N was applied obliquely, directed from the palatal to the buccal aspect, at a specific angle of 30 degrees. The stress distribution and fatigue performance were then evaluated considering the types of bone used and the angles of the three different abutments. The simulation aspect of the research was carried out utilizing Abaqus 2020 software.

RESULTS

In all models, fatigue strengths in healthy bone were higher than in resorbed bone. Maximum stress levels were seen in models with angled implants. In almost all models with resorbed bone, fatigue performances were slightly lower.

CONCLUSIONS

Increasing the abutment angle has been shown to increase stress levels and decrease fatigue performance in the adjacent bone and along the implant-abutment interface. In general, implants applied to healthy bone were found to have a higher success rate. It has also been suggested that multiunit abutments have beneficial effects on stress distribution and fatigue performance compared to resin cemented abutments. The type or angle of abutment and the quality of the bone can lead to biomechanical changes that affect the force distribution within the bone structure surrounding the implant. Clinicians can influence the biomechanical environment of the implant site by varying the abutment angle and type to suit the condition of bone health, potentially affecting the long-term success of implant treatment.

High insertion torque versus regular insertion torque: early crestal bone changes on dental implants in relation to primary stability-a retrospective clinical study

The aim of the presented retrospective study was to evaluate the early crestal bone changes around an implant type designed for high primary stability. A total number of 111 implants placed clinically were evaluated regarding insertion torque, bone density, implant stability quotient (ISQ) and early crestal bone loss from standardized digital radiographs. The implants were allocated in two groups: the "regular torque " group contained all implants that achieved less than 50 Ncm as final insertion torque (n = 63) and the "high torque" group contained the implants that achieved 50-80 Ncm (n = 48). To avoid possible damage either to the implant´s inner connection or to the bone by application of excessive force, a limit of 80 Ncm was set for all surgeries. All implants underwent submerged healing for three months. ISQ measurements and standardized digital radiographs were taken at day of insertion and at day of second stage surgery. The bone loss was measured on the mesial and distal aspect of the implant. The data evaluation showed the following results: Mean bone loss was 0.27 ± 0.30 mm for the high torque group and 0.24 ± 0.27 mm for the regular torque group. The difference was not statistically significant (p = 0.552). In the two groups, no complications nor implant loss occurred. For the evaluated implant type, there was no significant difference in crestal bone changes and complication rate between high and regular insertion torque in the early healing period.

The Importance of Correlation between CBCT Analysis of Bone Density and Primary Stability When Choosing the Design of Dental Implants—Ex Vivo Study

This study aims to determine the correlation between the mean value of bone density measured on the CBCT device and the primary stability of dental implants determined by resonant frequency analysis. An experimental study was conducted on a material of animal origin: bovine femur and pig ribs. Two types of implants were used in this study: self-tapping and non-self-tapping of the same dimensions. Results of the experimental study showed a statistically significant correlation between bone density expressed in HU units and the primary stability of self-tapping and non-self- tapping dental implants expressed in ISQ units in bovine femur bones and self-tapping implants and pig rib bones. There was no statistically significant correlation between non-self-tapping dental implants in pig rib bones. Self-tapping and non-self-tapping implants did not show statistical significance in the primary stability in bones of different qualities. The analysis of bone density from CBCT images in the software of the apparatus expressed in HU units can be used to predict the degree of primary stability of self-tapping and non-self-tapping dental implants in bones of densities D1 and D2, and self-tapping dental implants in bones of the lower quality D4.

Bone Quality Assessment of Dental Implant Recipient Sites

The term bone quality is not clearly defined and depends on many factors, such as bone density, bone vascularity, bone metabolism and other factors that may affect implant outcome. The assessment of bone volume and bone density is most common in planning the treatment of dental implants. Bone quality is an important predictor of primary implant stability, which influences the future implant osseointegration. Numerous classifications have been described for the evaluation of bone density. The most commonly used has been the one proposed by Lekholmu and Zarb. For the objective evaluation of bone density, conventional computed tomography (CT) or Cone Beam Computed tomography (CBCT), have been proposed. Both methods are reliable for the measurement of bone density, but preference is given to CBCT, due to the lower radiation doses, greater comfort for the patient and the lower prices. Pre-operatively defined bone density is a good indicator of the future success of implant therapy. In addition to the bone density, vascularity of the jawbone is an important factor of the quality of the bone for the osseointegration of dental implants. Laser Doppler is a simple method that can determine the vascularity of bone during implant insertion. The development of modern diagnostic methods for assessing the quantity and quality of the jawbone has enabled easier implant planning and has provided a secure outcome.

The clinical significance of implant stability quotient (ISQ) measurements: A literature review

Implant stability quotients (ISQ values) are obtained in dental clinical practice on a non-invasive basis by resonance frequency measurement rapidly after surgical placement of implants. The ISQ-values are used as indicator for mechanical implant stability, and are believed to have predictive power for clinical outcome. It is the aim of this review to provide a synopsis of all factors described in the literature that influence ISQ measurements by performing an exhaustive literature review; moreover, this review aims at elucidating the key factors relevant for a rapid clinical predictive assessment. We searched systematically and exhaustively all major databases for publications relating to ISQ measurement methodology and for ISQ-influencing factor analyses. The reports identified were ordered in experimental (preclinical) studies and in clinical publications. We were able to identify 13 basic factors influencing ISQ-measurements. Among these, local bone quality, playing a key role in such measurements, was subdivided in four specific subfactors; thus a total of 17 individual factors was identified and reported to influence ISQ-measurements. A comprehensive list of these factors is provided in Table-form. A critical analysis points out that only 6 of these factors are of a sound predictive power useful for a rapid clinical assessment; and only two of these factors appear to have a well-documented scientific basis.

Comparative Evaluation of Peri-implant Soft and Hard Tissue with and without Application of Bisphosphonate on Implant Surface and Osteotomy Site - A Clinico-radiographic, Cone-beam Computed Tomographic Study

Background:

The requisites to long-term success of dental implant are good-quality bone and healthy gingiva. Long-term risk with regard to dental implant is crestal bone loss. The cause of this crestal bone loss is inflammation of surrounding soft tissue and bone. One of the techniques used to prevent crestal bone loss includes the use of biological mediators. Bisphosphonates are antiresorptive drugs that act on osteoclasts and maintain bone density and strength by inhibiting osteoclast activity.

Materials and Method:

16 systemically healthy patients aged between 20 and 50 years desirous of replacing single missing posterior tooth with an adequate width and height of edentulous space included in the study. 8 patients were treated with application of bisphosphonate on implant surface and osteotomy site and 8 patients were treated only with implant therapy.

Results:

Crestal bone level changes were observed both in the study and control group. At 12 months, bisphosphonate-treated group showed less amount of crestal bone loss than control group.

Conclusion:

Local application of bisphosphonate (sodium alendronate) application around the implant and osteotomy site shows reduction in the amount of crestal bone loss but it is not statistically significant when compared with control group.

A Comparison between the Implant Stability Quotient and the Fractal Dimension of Alveolar Bone at the Implant Site

Objectives

Fractal analysis of the radiographic pattern of bone has been used to evaluate its quantitative properties. However, the relation between initial implant stability and quality of bone remains unclear. The objective of this study was to evaluate RFA values in relation to the fractal dimension of bone where the implant was inserted.

Material and Methods

A total of 50 two-stage dental implants were placed in the maxilla and mandible of 32 patients. After implant placement, an implant stability quotient (ISQ) was measured in two perpendicular planes. On intraoral digital periapical radiographs, three 35x35 pixels' regions of interest (ROIs) were chosen covering the bone adjacent to the neck (ROI 1), middle (ROI 2), and apical (ROI 3) part of the implant, respectively. For every ROI, a fractal dimension (FD) was calculated. A linear correlation, as well as a logistic regression analysis, was used to identify a possible relation between the ISQ and FD values for every ROI in the maxilla and mandible.

Results

The ISQ and FD values were found to be correlated at ROI 1 for the maxilla. There was no linear correlation between ISQ and FD values in any of the three ROIs in the mandible. However, logistic regression analysis showed that in ROI 1 and ROI 3 the values of FD and ISQ are statistically important and may be used to express the difference between maxilla and mandible.

Conclusion

The fractal dimension of alveolar bone measured from intraoral digital radiographs alone may be an insufficient parameter to determine initial implant stability.

Multivariate linear regression analysis to identify general factors for quantitative predictions of implant stability quotient values

Objectives

This study identified potential general influencing factors for a mathematical prediction of implant stability quotient (ISQ) values in clinical practice.

Methods

We collected the ISQ values of 557 implants from 2 different brands (SICace and Osstem) placed by 2 surgeons in 336 patients. Surgeon 1 placed 329 SICace implants, and surgeon 2 placed 113 SICace implants and 115 Osstem implants. ISQ measurements were taken at T1 (immediately after implant placement) and T2 (before dental restoration). A multivariate linear regression model was used to analyze the influence of the following 11 candidate factors for stability prediction: sex, age, maxillary/mandibular location, bone type, immediate/delayed implantation, bone grafting, insertion torque, I-stage or II-stage healing pattern, implant diameter, implant length and T1-T2 time interval.

Results

The need for bone grafting as a predictor significantly influenced ISQ values in all three groups at T1 (weight coefficients ranging from -4 to -5). In contrast, implant diameter consistently influenced the ISQ values in all three groups at T2 (weight coefficients ranging from 3.4 to 4.2). Other factors, such as sex, age, I/II-stage implantation and bone type, did not significantly influence ISQ values at T2, and implant length did not significantly influence ISQ values at T1 or T2.

Conclusions

These findings provide a rational basis for mathematical models to quantitatively predict the ISQ values of implants in clinical practice.