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

Fractal analysis of the trabecular bone pattern in the presence/absence of metal artifact-producing objects: Comparison of cone-beam computed tomography with panoramic and periapical radiography

OBJECTIVES

The effect of metallic objects on the fractal dimension (FD), bone area fraction (BAF) and gray scale values (GSVs) of cone-beam CT (CBCT) images was assessed. Also, FD, BAF and GSV were compared among CBCT, digital periapical and panoramic radiographies.

METHODS

Digital periapical and panoramic radiographs were acquired from six blocks of bovine rib. Additionally, different arrangements of titanium implants and intracanal metallic posts were created in the bone blocks and CBCT scans were taken from the different implant-root arrangements. The three radiographical modalities were compared by analysis of variance. Pairwise comparisons between the modalities were performed by the Tukey test (significance level set at 0.05).

RESULTS

Different root-implant arrangements in the CBCT images revealed no significant differences in the FD (p = 0.920), BAF and GSV values (p = 0.623). FD differed significantly among the three modalities (p < 0.001). Significant differences were found between CBCT and each of the periapical and panoramic techniques (p < 0.001), while no remarkable differences were observed in the FD of the periapical and panoramic images (p = 0.294). BAF and GSV showed significantly different results among the three radiographical techniques (p < 0.001). The difference was remarkable between CBCT and periapical (p < 0.001), CBCT and panoramic (p < 0.001) and periapical and panoramic (p = 0.008).

CONCLUSION

Presence of titanium implants and intracanal posts does not produce different results in the fractal analysis (FA) of the CBCT images. The trabecular bone pattern is best assessed by FA of the periapical radiographs followed by the panoramic and CBCT techniques, respectively.

An experimental study on the effects of the cortical thickness and bone density on initial mechanical anchorage of different Straumann® implant designs

Background

The aim of the current study was to comparatively assess the primary stability of different Straumann® implant designs (BLX, Straumann Tapered Effect, Bone Level Tapered, and Standard Plus) via resonance frequency analysis by using an implant insertion model in freshly slaughtered bovine ribs with and without cortical bone. Tapered Effect (4.1 × 10 mm), Bone Level Tapered (4.1 × 10 mm), Standard Plus (4.1 × 10 mm), and BLX (4.0 × 10 mm) implants were inserted into the distal epiphysis on the longitudinal axis of the freshly slaughtered bovine ribs. As a control, implants with the same sizes were inserted into the proximal diaphysis. The stability of the implants was examined with resonance frequency analysis.

Results

BLX and Tapered Effect implants showed higher implant stability quotient values in both study and control groups. All implant systems showed a significant decrease of mechanical anchorage in the study group. BLX and Bone Level Tapered designs had a significantly lower loss of mechanical anchorage in the lack of cortical bone.

Conclusion

Both Tapered Effect and BLX designs could ensure sufficient initial stability; however, BLX implants could be an appropriate option in the lack of cortical bone and poor bone quality at the implant recipient site.

Clinical relevance

BLX is a novel implant system, which could be especially beneficial in the presence of spongious bone type at posterior maxillae.

Fractal analysis as a useful predictor for determining osseointegration of dental implant? A retrospective study

PURPOSE

The present study aimed at evaluating the effectiveness of fractal analysis on determining the osseointegration of dental implants.

MATERIAL AND METHODS

In a single center, retrospective clinical trial, patients with dental implants in the mandibular premolar/molar region, ASA I-II and < 65-year-old patients were included. Orthopantomograph (OPG) were taken before implant surgery (t0), within a week of surgery (t1), and 1 (t2) and 2 (t3) months after surgery, respectively. Three regions of interest (ROIs) from mesial, distal, and apical sites of the implants were chosen and fractal analysis (FA) was conducted with the box-counting algorithm using White and Rudolph's method.

RESULTS

A total of 39 patients 19 women and 20 men, with a mean age of 52.2 years (52.3 and 52.1 years, respectively) were included. The mean, minimum and maximum values of mesial (roi1), distal (roi2), and apical (roi3) surfaces were compared. The fractal dimension (FD) values of t1 were significantly lower compared with t0 as they decreased during the first week. FD values gradually increased after the first week although never exceeded the FD values of t0. Also, difference between mean FD values of t0 and t3 were found statistically significant (p < 0.05).

DISCUSSION

FA is a promising and noninvasive method to predict osseointegration of a dental implant based on dental radiographs, and it can help shorten the total treatment time.

Automatic measurement of mandibular cortical bone width on cone-beam computed tomography images

OBJECTIVE

The computed tomography cortical index (CTCI), computed tomography mandibular index (CTMI), and computed tomography index (inferior) [CTI(I)] are indexes obtained from cone-beam computed tomography images for the assessment of the mandibular cortex quality for implant planning or osteoporosis. However, cross-sectional image reconstruction for the measurements is labor-intensive. This study aimed to develop and evaluate a method to automatically reconstruct cross-sectional images and measure the cortex width in all areas inferior to the mental foramen (MF).

METHODS

Seventy-one women (mean age: 52.4 years; range: 20-78 years) were enrolled. They were divided into four age and CTCI groups, including females younger (FY) and females older (FO) than 50 years (C1: normal, C2: mild/moderate erosion, and C3: severe porosity). Automatic and manual measurements of CTMI and CTI(I) were compared, and the inter- and intraobserver agreements were assessed using the intraclass correlation coefficient (ICC). The relationships between CTMI or CTI(I) and CTCI were also assessed.

RESULTS

The mean processing times for reconstruction and measurements were 31.9 s and 1.22 s, respectively. ICCs for the comparison of automatic and manual measurements were 0.932 and 0.993 in the C1 and C2/C3 groups, respectively. Significant differences in CTMI and CTI(I) were observed between the FY or the FO-C1 and FO-C3 groups (p < 0.05).

CONCLUSION

The automatic and manual measurements showed a strong agreement. The new method could drastically reduce routine clinical workload. Additionally, our method enables the measurement of the cortex width in all the mandibular bones inferior to the MF.

Mandibular cortical indices and their relation to gender and age in the cone-beam computed tomography

OBJECTIVES

The purpose of this study is to evaluate normal ranges of cortical bone Hounsfield units indices through cone beam CT images, and to investigate their relationships with age and sex.

METHODS

700 adult human cone beam CT images were evaluated retrospectively, and divided into 4 age groups. Six different cortical bone Hounsfield unit measurements were applied bilaterally, where gender and age were recorded. Collected data were subjected to statistical analysis and ANOVA tests were used for various comparisons.

RESULTS

The cortical bone measurements between female and male patients were significantly different (p<0.05). Cortical bone thickness indices showed greater values in male patients compare to female patients (p<0.05). Quantitative mandibular indices were significantly lower in first age group (18-30 years) than other three older age groups (p<0.01).

CONCLUSION

The results of this study seems to propose a persistent alteration in the mandibular cortical bone with age and that this influced by sex. Further studies with larger patient groups are needed to clarify and understand these mandibular indices.

Influence of cortical bone and implant design in the primary stability of dental implants measured by two different devices of resonance frequency analysis: An in vitro study

Background

This study aimed to evaluate the effect of the implant design and the presence of cortical bone in the primary stability, as well as analyze the differences between the stability measurements obtained by two different resonance frequency analysis (RFA) devices.

Material and Methods

A total of 80 Klockner implants of two different models [40 Essential Cone implants (group A) and 40 Vega implants (group B)] were used. The implants were placed in two polyurethane blocks that simulated the mechanical properties of the maxillary bone. One block featured a layer of cortical bone that was absent from the other block. The primary stability of all implants was measured by insertion torque and RFA using two different devices: Penguin RFA and Osstell IDX.

Results

Primary stability was superior in the cortical bone in both torque and RFA. In the block containing cortical bone, group A implants obtained a greater insertion torque than did group B. The insertion torque was lesser in the bone lacking cortex. Regarding the ISQ of the implants, group A presented higher values in the block with cortical bone, but the values were lower in the block without cortical bone. There were no significant differences between the values obtained from the Osstell IDX and Penguin RFA.

Conclusions

The presence of cortical bone positively influences the primary stability of dental implants. The design of the implant also has a statistically significant influence on implant primary stability, although the impact depends on whether there is coronal cerclage or not. There were no statistically significant differences in the implant stability measurements obtained by two different devices.

Key words:Implant stability, resonance frequency analysis, torque, osstell, penguin, cortical.

Comparison of mandibular cortical bone among obese, overweight, and normal weight adolescents using panoramic mandibular index and mental index

OBJECTIVE

The objective of this study is to evaluate the mental index (MI) and panoramic mandibular index (PMI) of a group of adolescent patients in different body mass index (BMI) percentile.

MATERIAL AND METHODS

Subjects were divided into three different groups in accordance to their BMI percentile status: normal weight (35 subjects; mean age, 14.81 ± 2.12 years), overweight (32 subjects; mean age, 14.77 ± 2.56 years), and obese (33 subjects; mean age, 14.06 ± 2.59 years) groups. Mental index (MI) and panoramic mandibular index (PMI) were assessed on panoramic radiographs.

RESULTS

There were statistically significant differences in PMI and MI that were observed among groups (p < 0.0001 and p < 0.001, respectivel). MI and PMI are higher in overweight and obese individuals than in normal-weight.

CONCLUSIONS

Mandibular cortex was found thicker in patients who are obese and overweight compared to normal weight patients. We can suggest that young obese individuals' bone structure can be take in consideration in orthodontic or dental surgical treatment planning.

CLINICAL RELEVANCE

Dense cortical bone may cause some difficulties in orthodontic and surgical treatment. Clinicians should understand obesity and overweight-related jaw bone changes and consider these factors to treat their patients.

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.

A "best fit" approach for synergistic surface parameters to guide the design of candidate implant surfaces

Human bone resorption surfaces can provide a template for endosseous implant surface design. We characterized the topography of such sites using four synergistic parameters (fractal dimension, lacunarity, porosity, and surface roughness) and compared the generated values with those obtained from two groups of candidate titanium implant surfaces. For the first group (n = 5/group): grit-blasted acid etched (BAE), BAE with either discrete calcium phosphate crystal deposition or nanotube formation, machined titanium with nanotubes, or a nanofiber surface; each measured synergistic parameter was statistically compared with that of the resorbed bone surface and scored for inclusion in a "best fit" analysis. The analysis informed changes that could be made to a candidate implant surface to render it a closer "best fit" to that of the resorbed bone surface. In a second group of either titanium or titanium alloy implants their micro-topography, created by dual acid etching, was the same for each material substrate; but their nanotopographic complexity was changed by varying the degree of calcium phosphate crystalline deposits. These implants were also used in vivo where bone anchorage was tested using a tensile disruption test; and the "best fit" of synergistic parameters coincided with the best biological outcome for both titanium and titanium alloy implants. In conclusion, the four chosen synergistic parameters can be used to guide the sub-micron surface design of candidate implants, and our "best fit" approach is capable of identifying the surfaces with the best biological outcomes. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2165-2177, 2019.

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.

Effects of different loading protocols on the secondary stability and peri-implant bone density of the single implants in the posterior maxilla

BACKGROUND

Immediate or early loading of dental implants becomes a clinically feasible concept.

PURPOSE

The aim was to evaluate the effects of different loading protocols (immediate, early, and delayed) on secondary stability and peri-implant bone density of single implants in the posterior maxilla.

MATERIALS AND METHODS

Thirty-nine implants (Dentium, South-Korea) were placed in 39 patients. After placement, implant stability values (ISQ) and baseline peri-implant bone density values derived from cone-beam computed tomography were recorded. Thirteen implants were included randomly in each loading groups. The secondary ISQ values were recorded during follow-up visits. Peri-implant bone density values were measured 1 year after placement again. Data was statistically analyzed.

RESULTS

Immediate-loaded group showed the lowest ISQ values, 1 month after placement. During the next follow-up visits, delayed-loaded group showed the lowest ISQ values while other groups showed comparable results. Early loading increased the peri-implant bone density greater than the other groups.

CONCLUSIONS

The peri-implant bone of early-loaded implants was significantly denser than that of immediate- and delayed-loaded implants, 1 year after placement. Density increment can be judged as the radiological findings of loaded-bone, which may also reduce the need for histomorphometric analysis of human biopsy to evaluate the bone reaction around the implants.