Bone density assessments of dental implant sites: 3. Bone quality evaluation during osteotomy and implant placement.

PURPOSE: In previous publications of this series of studies on human cadaver jaws, bone densities were assessed and compared using subjective evaluation, conventional computed tomography (CT), and cone-beam computed tomography (CBCT). The aim of this study was to compare subjective bone quality during osteotomy and implant insertion resistance torque to noninvasive subjective and objective radiographic bone density assessments. MATERIALS AND METHODS: Forty-two designated implant sites were selected. Self-tapping implants were inserted into these sites. The operator subjectively rated the bone density during the osteotomy procedure. Resistance torque was recorded during insertion of the implants. RESULTS: Subjective drilling resistance was modestly correlated to subjective radiographic density evaluation (Lekholm and Zarb; Spearman's rho of 0.53, P < .001). Subjective drilling resistance compared to the bone density in Hounsfield units (HU) obtained using CT and CBCT showed correlation coefficients of 0.61 and 0.59, respectively (P < .001). Significant overlap of density values was found for adjacent drilling ratings. On average, a difference in bone density of 180 HU was required to identify differences between drilling resistance groups. Comparisons of 2 implant insertion resistance torque variables (highest reading and regression slope of available readings) with CT and CBCT HU showed correlation coefficients of 0.61 to 0.63 (P < .01). CONCLUSION: Insertion torque resistance was modestly correlated with objective CT and CBCT measurements of bone density. The merit of these assessments of cadavers awaits clinical study.

Bone density assessments of dental implant sites: 2. Quantitative cone-beam computerized tomography.

PURPOSE: Bone density was evaluated in designated implant sites using a novel volumetric computerized tomographic device. Those measurements were then compared with traditional quantitative computerized axial tomography and subjective bone density evaluation. MATERIALS AND METHODS: Sixty-three potential sites for implant placement in jaws from 9 human cadavers were used. Indicator rods 2 mm in diameter were placed in all sites. Radiographic images representing 1-mm buccolingual slices immediately mesial and distal to the rods were selected. Bone density in Hounsfield units was assessed using quantitative cone-beam computerized tomography (QCBCT) and quantitative computerized tomography (QCT) in a standardized implant area superimposed on the images. Bone density was also subjectively evaluated by 2 independent examiners using the Lekholm and Zarb classification. RESULTS: The QCBCT bone density values were generally found to be higher than the corresponding QCT measurements. The correlations between the QCT and QCBCT values, however, were very high in spite of this systematic difference between the 2 methods. The Lekholm and Zarb ratings for the 2 examiners showed correlation coefficients ranging between 0.46 and 0.60 for the relationships with the QCBCT values. For each of the scores used for the subjective classification, however, a wide range of corresponding QCBCT values was observed. DISCUSSION: High dosage has been the major impediment to the utilization of CT in implant dentistry. The development of a reliable volumetric CT alternative with reduced radiation should provide an effective method for the assessment of both bone quantity and bone density. CONCLUSIONS: Access to objective radiographic bone density values should constitute a valuable supplement to subjective bone density evaluations prior to implant placement. QCBCT could be considered an alternative diagnostic tool for preoperative bone density evaluation, especially since the reported radiation dose is minimal.

Bone density assessments of dental implant sites: 1. Quantitative computed tomography.

PURPOSE: This study was designed to evaluate variations of bone density in designated implant sites using quantitative computed tomography (QCT) and to compare the QCT measurements to subjective evaluation of bone density. MATERIALS AND METHOD: Sixty-two designated implant sites in jaws of 9 human cadavers were used. Indicator rods, 2 mm in diameter, were placed in all sites. CT images representing 1-mm buccolingual slices immediately mesial and distal to the rods were selected. Bone density (in Hounsfield units) was assessed in a standardized implant area superimposed on the images and was also subjectively evaluated by 2 independent examiners using the Lekholm and Zarb classification. RESULTS: QCT results demonstrated that bone densities may vary markedly when different areas of a designated implant site are compared. The Lekholm and Zarb ratings for the 2 examiners showed coefficients of correlation ranging between 0.5 to 0.7 for the relationships with the QCT values. Within each of the scores used for the subjective classification, however, a wide range of QCT values was observed. DISCUSSION: The results emphasize the importance of the use of radiographic methods prior to implant placement that allow topographically precise assessments of bone density in the region of interest. CONCLUSION: Access to QCT values should constitute a valuable supplement to subjective bone density evaluations prior to implant placement.

Probing bone level measurements for determination of the depths of Class II furcation defects.

BACKGROUND: Probing bone measurements as an alternative to open bone measurements to evaluate regenerative procedures in furcation defects do not seem to be used as yet. The purpose of the present study was to investigate the reliability of probing bone measurements in such defects. METHODS: Fifteen patients scheduled for surgical treatment of a total of 30 mandibular molars with buccal or lingual Class II furcation defects were studied. During treatment, duplicate vertical and horizontal recordings of probing attachment levels, probing bone levels, and open bone levels were taken by independent examiners. RESULTS: Deviations of both vertical and horizontal recordings between the first and second examiners were within +/-1 mm in 90% to 100% of examined sites for all 3 measurements. Standard deviations of differences between pairs of duplicate recordings were also similar for the 3 measurements both for vertical and horizontal defect dimensions and amounted to 0.7 to 0.9 mm. On average, vertical and horizontal open bone levels were 0.9 to 1.1 mm deeper than probing bone levels. Probing bone levels, in turn, were 1.1 to 1.5 mm deeper than probing attachment levels. CONCLUSIONS: In view of the consistency demonstrated between probing bone level and open bone level measurements in mandibular Class II defects, coupled with the additional discomfort for the patient of a reentry surgery and a possible reentry traumatic effect, open bone level measurements do not seem necessary or even justified to evaluate effects of periodontal therapy in these defects, and can be substituted by probing bone measurements.

Pain experienced by patients during periodontal maintenance treatment.

BACKGROUND: The aims of this study were to assess the degree of pain experienced by patients during probing and debridement and to determine whether the pain responses could be predicted by the patient's age, gender, percentage of sites > or = 4 mm deep, and responses to a questionnaire on dental anxiety. METHODS: Prior to the maintenance procedures, 26 adult patients completed an anxiety questionnaire. Subsequently, measurements of probing depths were performed. The patients activated a tallying device at each probe entry that evoked pain (pain frequency). Pain levels for each quadrant were also assessed with a visual analog scale (VAS). Following probing, the same protocol was repeated during instrumentation (debridement). RESULTS: Most patients showed low pain responses to both probing and instrumentation as evaluated by both methods of measurement. However, using arbitrary thresholds of pain frequency > or = 50% and VAS > or = 40 mm, approximately 15% of the patients had a painful experience. Stepwise multiple regression analyses disclosed that significant portions of the pain levels could be predicted by gender and the patients' answers to 2 of the dental anxiety questions. CONCLUSIONS: Recognition of patients who are likely to experience pain during periodontal treatment can be facilitated by the use of 2 questions on dental anxiety and the VAS response to probing during examination.