Damping factor for monitoring the bone interface at dental implants

Fractal Dimension as a Tool for Assessment of Dental Implant Stability—A Scoping Review

A lot of modalities for assessing implant stability are available for clinicians, but they fail to assess trabecular changes as they are solely dependent on the operator’s skills. The use of Fractal Dimension (FD) has evolved to be used as a measure for trabecular changes depicting implant stability before and after implant placement. The objective of this systematic review was to qualitatively analyse the available scientific literature describing the use of FD as a tool to measure implant stability on the basis of trabecular changes. An electronic search in PubMed, Web of Science and Scopus was carried out using relevant keywords, such as: fractal dimension; fractal analysis; dental implants; implant stability; osseointegration, etc. Studies reporting the use of FD as a tool to measure implant stability were included and subjected to qualitative analysis using ROBINS-I and Cochrane risk of bias assessment criteria. Fourteen studies were included in this review. Results showed that FD was found to be used solely as a measure of implant stability in seven studies, out of which six studies showed an increment in FD values. The majority of studies concluded with a statistical correlation between FD and respective other assessment methods used. FD may not serve as a sole indicator of implant stability; however, it can be used as an adjunct to conventional methods along with additional fractal factors.

Characterization of the viscoelasticity of pharmaceutical tablets using impulse excitation technique

Pharmaceutical tablets can be produced on different kinds of presses that may have very different compaction kinematics. Strain rate sensitivity (SRS) is thus an important property for the powders used to produce pharmaceutical tablets. Viscoelasticity is one of the aspects of the SRS and can be sometimes difficult to characterize. In this work, impulse excitation technique was used as an easy-to-implement method for characterizing viscoelasticity using the fact that this property induces damping which can be detected on resonance spectra as peak enlargements. A damping ratio, related to the first flexural vibration mode, was determined on impulse excitation frequency spectra using the half-power bandwidth method on tablets made with different products. This method made it possible to obtain reproducible results for the damping ratio. As viscoelasticity is not the only phenomena that can promote damping, tests were made in order to assess the influence of other parameters: viscoplasticity, porosity and tablet dimensions. Results indicated that the influence of these phenomena could be considered as negligible. Finally, the damping ratios determined were in good accordance with the known viscoelastic behavior of the studied products. This made it possible to confirm that impact resonance is an easy and quick way to characterize the viscoelastic nature of pharmaceutical tablets.

Comparison of Measurements of Implant Stability by Two Different Radio Frequency Analysis Systems: An In Vitro Study

Aim:

To compare and evaluate the implant stability quotient (ISQ) measurements by two different radio frequency analysis (RFA) machines, Osstell Mentor and PenguinRFA.

Materials and Methods:

Twenty bone-level implants (3.7 × 10 mm2) were placed on a bovine bone in this in vitro study. The ISQ measurements were performed with the PenguinRFA and Osstell Mentor machines using the multipeg of the Penguin system. The measurements were repeated three times for each direction and an average ISQ value was calculated. The results were averaged (mean ± SD) and the intraclass correlation coefficient (ICC) was calculated to assess the relationship between the measurements.

Result:

The mean ISQ values for the Osstell and Penguin machines were 77.60 + 2.11 and 78.05 + 2.04, respectively. The ICC was 0.958. The ISQ values obtained from the Osstell and Penguin machines were significantly compatible ( P < .05).

Conclusion:

Both of the RFA devices provided similar and reliable ISQ measurements.

Use of fractal analysis in dental images: a systematic review

OBJECTIVES

This study reviewed the use of fractal analysis (FA) in dental images.

METHODS

A search was performed using PubMed, MEDLINE, LILACS, Web of Science and SCOPUS databases. The inclusion criteria were human studies in the English language, with no date restriction.

RESULTS

78 articles were found in which FA was applied to panoramic radiographs (34), periapical radiographs (21), bitewing radiographs (4), cephalometric radiograph (1), cone beam CT (15), micro-CT (3), sialography (2), and ultrasound (2). Low bone mineral density (21) and systemic or local diseases (22) around the bone of dental implants were the main subjects of the study of FA. Various sizes and sites of the regions of interest were used to evaluate the bone structure. Different ways were used to treat the image and to calculate FA. FA of 43 articles showed significant differences in the comparison of groups, mainly between healthy and sick patients.

CONCLUSIONS

FA in Dentistry has been widely applied to the study of images. Panoramic and periapical radiographs were those most frequently used. The Image J software and the box-counting method were extensively adopted in the studies reviewed herein. Further studies are encouraged to improve clarification of the parameters that directly influence FA.

Bone Texture Fractal Dimension Analysis of Ultrasound-Treated Bone around Implant Site: A Double-Blind Clinical Trial

Objectives

To evaluate the efficacy of bone texture fractal dimension (FD) analysis method in predicting implant stability from intraoral periapical radiographs using two implant protocols.

Materials and Methods

A double-blind clinical trial was conducted on 22 subjects who needed dental implants. The participants were randomized into two groups, the control group with standard implant protocol treatment and the intervention group with added low-intensity power ultrasound treatment (LIPUS) besides the standard implant protocol. The FD values of bone density were carried out on the mesial and distal sides of the implant on digital intraoral radiographs using the box-counting method. Both resonance frequency (RF) and fractal dimension (FD) were assessed in three time intervals: after surgery and before and after loading.

Results

FD on both the mesial and distal sides serve as very good-to-excellent tests with high validity (ROC area exceeding 0.8) in predicting high implant stability (ISQ ≥ 70). The mesial side measurements were consistently better than the distal side among the intervention groups. The optimum cutoff value for the FD-mesial side that predicts a highly stable implant (ISQ ≥ 70) is ≥1.505. At this optimum cutoff value, the mesial side FD is associated with a perfect sensitivity (100%) and fairly high specificity (86.5%).

Conclusion

The FD analysis could be recommended as an adjunctive quantitative method in prediction of the implant stability with very high sensitivity and specificity. This trial is registered with ISRCTN72648040.

Radiographic Fractal and Clinical Resonance Frequency Analyses of Posterior Mandibular Dental Implants: Their Possible Association With Mandibular Cortical Index With 12-Month Follow-up

BACKGROUND

The aim of the present study was to investigate whether the mandibular cortical index (MCI) has a relationship with fractal dimension of bone and/or implant stability, and to justify the possible association between MCI, fractal dimension, and stability.

MATERIALS AND METHODS

Eighty-two subjects who received dental implants to replace missing mandibular premolar/molar sites were selected. Three months after surgical placement, implants were restored with fixed ceramic fused metal crowns. MCI was evaluated at baseline; fractal dimensions were measured with fractal analysis (FA) and implant stability quotient (ISQ) with resonance frequency analysis immediately after surgery and 12-month follow-up.

RESULTS

FA at mesial and distal regions for Class 1, Class 2, and Class 3 MCI resulted with significant increases at 12-month follow-up compared to baseline. The ISQ in patients with Class 2 and Class 3 MCI resulted with a significant decrease compared to Class 1 MCI at baseline and at 12 months. All MCI classes evaluated with ISQ and FA at baseline values resulted with significant increases at 12 months. Significant correlations were considered for all mandibular posterior implants between baseline and 12-month measurements for ISQ and FA evaluations.

CONCLUSIONS

Fractal analysis may be a useful method for understanding the healing process around implants and implant stability quotient values. Mandibular cortical index evaluations should be considered before implant procedures, which may provide a presurgical treatment plan and may provide information about the mandibular bone quality.

Fractal analysis for the assessment of trabecular peri-implant alveolar bone using panoramic radiographs

OBJECTIVES

There is no consensus on the relationship between fractal dimension and trabecular bone complexity. Our aims were to examine the changes in fractal dimension (FD) from peri-implant alveolar bone on digital panoramic radiographs 6 and 12 months after prosthodontic loading and to compare these with baseline values calculated just after loading.

MATERIAL AND METHODS

Three panoramic radiographs taken from 76 implant patients taken (1) after prosthodontic loading (3 months ± 2 weeks after insertion = baseline), (2) 6 months ± 2 weeks after loading, and (3) 12 months ±2 weeks after loading were considered for the study. Panoramic images were obtained using storage phosphor plates of the Digora PCT system and saved into a computer. Three regions of interest from mesial, distal, and apical areas were selected for each implant on three consecutive panoramic images. Statistical analysis of the data was performed using two-way repeated measures ANOVA, independent t test and paired t test, and pairwise comparisons (P < 0.05).

RESULTS

Mean FD values at baseline were 1.202, 1.224, and 1.199 for apical, mesial, and distal areas. The FD values were calculated as 1.121, 1.113, and 1.128 at the 6th month. The differences between values calculated at baseline and the 6th month were statistically significant for all aspects, indicating a significant decrease in FD 6 months after prosthodontic loading (P < 0.05). FD values calculated at the 12th month were 1.121, 1.110, and 1.121 for apical, mesial, and distal aspects, respectively, with no significant differences from corresponding values obtained at the 6th month (P > 0.05).

CONCLUSIONS

FD values of trabecular bone around implants 6 months after prosthodontic loading are significantly lower than the baseline values. However, no significant decrease or increase was observed at 12 months, which revealed comparable results with peri-implant alveolar bone at 6 months.

CLINICAL RELEVANCE

Trabecular bone around successful dental implants exhibits lower fractal dimension values 6 months after prosthodontic loading and displays stable bony microstructure at 12 months of follow-up.

Preoperative computed tomography-derived bone densities in hounsfield units at implant sites acquired primary stability

The purpose of this study was to evaluate preoperative CT-derived bone densities in Hounsfield units (HU) at implant sites that acquired primary stability, and to compare these values to the optimal bone densities proposed in the literature. Fifty-one patients, 18 males (37 implant sites) and 33 females (67 implant sites) between 2003 and 2010 were assessed. CT data for different jaw sections, regions, and operating procedures were compared using the Kruskal-Wallis test and Scheffe's test for multiple comparisons (P < 0.05). The mean bone density in the maxilla was significantly lower than that in the mandible (P < 0.05); the mean bone densities in the 4 jaw regions decreased in the following order: anterior mandible > anterior maxilla > posterior mandible > posterior maxilla. The bone densities assessed by HU fell into the range of optimal bone densities associated with acquired primary implant stability proposed in the literature.