Assessment of correlation between pre-operative radiologic bone density and subjective bone quality score, insertion torque and resonance frequency analysis in dental implant surgery

Sufficient bone quality as well as sufficient bone dimension is crucial in terms of treatment succes of dental implants. Thus, pre-operative evaluation of bone quality is necessary for treatment success. Dental implants have been a popular alternative in the dental rehabilitation after the introduction of osseointegration. The success and survival of dental implants have become increasingly important along with the rapid increase in the number of dental implants installed. The success of dental implant treatment is influenced by both the quality and quantity of available bone for implant placement. Studies have shown higher failure rates for implants placed in bone of poor quality and quantity. Hence, a precise evaluation of bone structure before surgery is crucial during treatment planning. Bone quality is a key factor to take into account when predicting implant stability. A good stability favors implant osseointegration. Thus, several classification systems and procedures have been defined for assessing bone quality. Implant stability can be predicted subjectively by surgeon's assumption about bone quality during bone drilling procedure before implant placement. Implant stability can also be evaluated objectively by the insertion torque test and resonance frequency analysis (RFA) after implant placement. All of these methods provide information about bone quality during implant surgery. However; predictable techniques, which correlate with the methods used during surgery, are necessary to predict implant stability before surgery. Thus, the concept of using CT, as a more objective method for preoperative quantitative assessment of bone density, has had increasing popularity during the past few years. A number of studies have shown the relationship between bone density on CT and primary implant stability. However, patients were exposed to high radiation during CT scanning. Recently, cone beam CT (CBCT) technique, specifically designed for head and neck imaging, was introduced. The advantages of CBCT are imaging with high resolution, potentially lower radiation dose, and reduced costs compared with CT. On the other hand, there are several disadvantages of CBCT including scattered radiation, the limited dynamic range of the X-ray detectors, and density values without a linear correlation with bone density. Limited contrast resolution continues to impair low-contrast detectability in CBCT images. However, significant correlations between the density values of CBCT and Hounsfield unit (HU) of multislice CT were also reported in recent studies. Consequently, deriving bone density values from CBCT images seems controversial. In the literature, there are only limited number of studies about the correlation between bone density estimated by CBCT and primary implant stability. With this background, the aim of the present study was to explore the efficacy of bone density value derived from CBCT by evaluating its correlation with implant stability parameters including insertion torque value (ITV) and radiofrequency analysis (RFA) in relation to different clinical variables including location, gender, age, bone quality, and implant diameter. Key Words: Dental implant, bone density, cone beam computed tomography (CBCT), resonance frequency analysis (RFA), insertion torque (ITV)