Bone density assessments of oral implant sites using computerized tomography

Evaluation of Effect of Different Insertion Speeds and Torques on Implant Placement Condition and Removal Torque in Polyurethane Dense D1 Bone Model

The aim of this study was to evaluate the effect of two different insertion speeds at eight different insertion torque values ranging from 25 to 60 during implantation in a dense polyurethane (PU) D1 bone model on the placement condition and removal torque of dental implants. In this study, 50 pcf single-layer PU plates were used. In the study, a total of 320 implant sockets were divided into two groups, Group 1 (30 rpm) and Group 2 (50 rpm), in terms of insertion speed. Group 1 and Group 2 were divided into eight subgroups with 25, 30, 35, 40, 45, 50, 55 and 60 torques. There were 20 implant sockets in each subgroup. During the implantations, the implant placement condition and removal torque values were assessed. There was a statistically significant difference between the 30 and 50 rpm groups in terms of overall implant placement condition (p < 0.01). It was found that the removal torque values at 50 rpm were statistically significantly higher than those at 30 rpm (p < 0.01). This study showed that in dense D1 bone, the minimum parameters at which all implants could be placed at the bone level were 50 torque at 30 rpm and 40 torque at 50 rpm.

Mandibular molar protraction: A comparison between fixed functional appliances and temporary anchorage devices

INTRODUCTION

This study aimed to compare the efficiency of temporary anchorage devices (TADs) and fixed functional appliances (FFAs) for mandibular molar protraction.

METHODS

Orthodontic records of 1050 consecutively treated patients with molar protraction were screened. Thirty-six records (22 females and 14 males; mean age, 17.4 years) were divided into two groups: TAD (21 subjects with 25 edentulous spaces) and FFA (15 subjects with 24 edentulous spaces). The primary outcome measure was the efficiency of protraction [magnitude and time required for protraction (rate) and anchor loss (AL)]. The secondary outcomes involved measuring the type of tooth movement (TOTM), external apical root resorption (EARR), alveolar bone height change (ABHC), alveolar bone width change (ABWC) and appliance failure.

RESULTS

The rate of tooth movement was significantly higher for FFAs (0.83 ± 0.35 mm/month) versus TADs (0.49 ± 0.2 mm/month) (P = .005). Total treatment duration was less for FFAs (34.78 ± 8.1 months) versus TADs (47.72 ± 13.94 months) (P = .002). TOTM was similar for both (P = .909). EARR was 1.42 ± 1.38 mm for TAD and 1.25 ± 0.88 mm for FFA (P = .81). ABHC increased in the FFA group (1.01 ± 3.62 mm) and decreased for the TAD group (0.68 ± 1.66 mm). ABWC increased for both TAD (1.81 ± 1.73 mm) and FFA (1.75 ± 1.35 mm). The failure rate was 50% for FFAs and 33% for TADs.

CONCLUSIONS

Both systems provided translation of lower molars with comparable anchorage control. However, FFAs were more efficient than TADs for lower molar protraction.

Assessment of bone density in edentulous maxillae using cone beam computed tomography (CBCT)

INTRODUCTION

In edentulous maxillae, the anterior maxilla is the region of interest for implant placement due to posterior bone resorption and sinus pneumatization. This study aimed to assess variations in bone density in different regions of the edentulous maxilla according to sex and age, using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

69 CBCT from edentulous maxilla were analyzed. Six virtual implants were planned between the maxillary sinuses at incisor, canine, and premolar sites. Bone densities (in Hounsfield units HU) were recorded at six points on the neck, body, and apex of the buccal and lingual areas of each virtual implant. We used the two-sample t-test to compare male and female bone densities, and the Spearman correlation coefficient to analyze the correlation between mean bone density and age. One-way analysis of variance with post hoc pairwise t-tests was used to analyze the differences in density between three sites of the edentulous maxilla and the differences in density between three parts of the implant. The significance level was set at 5%.

RESULTS

Mean bone density in males was significantly higher than in females. There was a significant correlation between mean bone density and age in females. Incisor sites showed the highest mean bone density, followed by canine and premolar sites. There was a significant decline in bone density from the neck to the apex.

CONCLUSIONS

Bone density varied within and among edentulous maxillae. Bone density of the edentulous maxilla seemed to be influenced by age in women and by sex.

Clinical outcomes of narrow- and regular-diameter implants with bone augmentation in the anterior maxilla: a systematic review and meta-analysis

OBJECTIVES

To evaluate the clinical outcomes of narrow-diameter implants (NDIs) and regular-diameter implants (RDIs) with bone augmentation in the anterior maxilla, with implant survival rate (ISR) as the primary outcome. Additionally, secondary outcomes such as peri-implant marginal bone loss (MBL), pocket probing depth (PPD), mechanical complications, and biological complications were also considered.

MATERIALS AND METHODS

A thorough literature search was performed to identify randomized controlled trials and cohort studies comparing outcomes of NDIs and RDIs with bone augmentation in the anterior maxilla published up to February 2024. Only studies with a minimum follow-up period of 12 months were selected for analysis. Meta-analysis was performed if at least two articles with similar characteristics were available.

RESULTS

Of the 288 articles initially considered, 5 were included in the analysis, involving 282 NDIs and 100 RDIs. At the 36-month follow-up, no statistically significant differences in ISR, which ranged 93.8-100% for NDIs and were 100% for RDIs, were observed between the two groups (relative risk, 0.989; 95% confidence interval, 0.839-1.165; p = 0.896). Similarly, MBL and PPD did not differ significantly between the two groups. Soft tissue dehiscence was the most common complication found in RDIs.

CONCLUSION

The results indicate that NDIs yield clinical outcomes similar to those of RDIs with bone augmentation in the anterior maxilla over a 36-month follow-up period.

CLINICAL RELEVANCE

Considering the similar clinical outcomes, the shortened treatment duration and more rapid esthetic improvement associated with NDIs may render them preferrable to RDIs with bone augmentation, particularly in this esthetic zone.

Histomorphometric and CBCT comparison of osseointegration around orthodontic titanium miniscrews coated with different nanoparticles: An in-vivo animal study

BACKGROUND

Temporarily installed titanium orthodontic miniscrews are usually used for many orthodontic applications, especially those cases that need high force, such as skeletally anchored orthodontic appliance cases. Surface modification of titanium miniscrews has proved success in preventing failure and overcoming their limitations.

OBJECTIVE

The present study aims at the assessment of the quality of osseointegration of surface modified titanium miniscrews installed in the maxilla of albino rabbits with cone-beam computed tomography (CBCT) imaging as well as histomorphometric investigations.

MATERIAL AND METHODS

The orthodontic titanium miniscrews (TMSs) were coated with silver/hydroxyapatite (Ag/HA) nanoparticles (NPs) or zinc oxide (ZnO) NPs via electrochemical deposition. The coating nanomaterials were then characterized with X-ray diffractometry (XRD) and scanning electron microscopy (SEM) imaging. Moreover, the antimicrobial activity of the coated titanium miniscrews were evaluated in the rabbits' oral cavity to investigate their ability to prevent biofilm formation.

RESULTS

It was found that the Ag/HA-coated TMSs demonstrated the highest antimicrobial activity and bone area fill, followed by the ZnO NPs-coated TMSs when compared to their uncoated counterparts. In the anterior area surrounding the installed TMSs, the highest osseointegration was demonstrated by ZnO NPs-coated TMSs. However, Ag/HA-coated TMSs showed the highest osseointegration values in the posterior peri-implant area.

CONCLUSIONS

Ag/HA- and ZnO NPs-coated TMSs may provide a promising solution to overcome the 30% probable failure in temporarily installed orthodontic miniscrews, as they can enhance the osseointegration process and prevent biofilm formation.

Clinical efficacy of 1% metformin gel around conventionally placed dental implants: A 9-month follow-up study

Aim

The study aimed to compare the clinical and radiographic outcomes of bone volume, density, and crestal bone levels in conventionally placed dental implants with and without local application of 1% metformin (MF) gel using cone-beam computed tomography (CBCT) at 9 months.

Materials and Methods

Twenty implants were placed in 18 individuals, randomly divided into 2 groups where Group A received a local application of 1% MF gel along with implant placement. In contrast, Group B received implant placement alone. After thorough clinical examination and preoperative CBCTs, implants were placed under aseptic conditions. Patients were recalled at 3 and 9 months after surgery. Implants were functionally loaded by the end of 3rd month. Soft-tissue parameters such as modified plaque index and modified sulcular bleeding index were recorded along with CBCT evaluation to assess the crestal bone loss, bone density measurement, and bone volume, postoperatively. Fisher's extract test, independent and paired t-test, and Bonferroni analysis were used to determine statistical significance with P ≤ 0.05.

Results

There was no discernible difference between the groups regarding soft-tissue parameters, bone density, and crestal bone levels. However, comparing bone volume between the test and control groups at 9 months was statistically significant. The test group with 1% MF gel showed increased bone volume around the implant.

Conclusion

The data obtained were strong enough to suggest that 1% MF gel administered locally can increase peri-implant bone volume, possibly due to its additional property favoring osteoblastic stimulation and proliferation.

Management of Posterior Mandibular Bone Cavitation for Dental Implant Placement: A Case Series of 5-24 Years of Follow-Up

Focal osteo-cavitation in the posterior mandible is a condition that clinicians do not know well. Inadvertent implant placement in such areas may result in nerve damage due to abrupt drill penetration and implant displacement in the medullary space. In the present case series, focal osteo-cavitation was managed with the following procedures: (1) undersized drilling, (2) gentle trabecular curettage, (3) bone substitute material grafting in the cavity, and (4) long healing period for osseointegration. In all cases, a sudden loss of drilling pressure immediately after passing through the thin cortical layer revealed focal osteo-cavitation. Following undersized drilling and gentle trabecular curettage, the bone substitute material was packed into the cavity with care not to press the inferior alveolar canal. Implant placement was subsequently performed. Despite a lack of primary implant stability in 3 of 4 cases, all implants were successfully osseointegrated after 6-9 months. Over 5-24 years, all implants functioned well.

Assessment of Radiodensity at Mandibular Periapical Bone Sites using Three-Dimensional Cone-Beam Computed Tomography

Objectives

The aims of this retrospective study were to objectively assess bone density values obtained by cone-beam computed tomography and to map the periapical and inter-radicular regions of the mandibular bone.

Material and Methods

In total, periapical bone regions of 6898 roots scanned by cone-beam computed tomography were evaluated retrospectively, and the results were recorded using Hounsfield units (HU).

Results

The correlation between periapical HU values of adjacent mandibular teeth were strongly positive (P ˂ 0.01). The anterior region of the mandible yielded highest mean HU value (633.55). The mean periapical HU value of the premolar region (470.58) was higher than that was measured for molar region (374.58). The difference between furcation HU values of the first and second molars was unnoticeable.

Conclusions

The results of this study have tried to evaluate the periapical regions of all mandibular teeth, which could ease to predict the bone radiodensity before implant surgery. Even though the Hounsfield units provide the average radio-bone density, a site-specific bone tissue evaluation of each case is essential for appropriate cone-beam computed tomography preoperative planning.

Effect of cigarette smoking on alveolar bone thickness and density in patients undergoing leveling and alignment of crowded lower anterior teeth: a controlled clinical trial

OBJECTIVE

To evaluate the effect of cigarette smoking on the alveolar bone thickness and density in patients undergoing leveling and alignment of crowded lower anterior teeth.

METHODS

This controlled clinical trial involved 17 smokers and 17 nonsmokers with mild to moderate crowding of the anterior mandibular teeth. Two cone-beam computed tomography images of the mandible were taken before and after treatment. The length of each tooth root was calculated in each T0 image, and the root was divided into three equal regions. Three lines were drawn parallel to the line of the cementoenamel junction at these three regions of the root, and the previously drawn lines were used to measure bone thickness and bone density.

RESULTS

The mean changes in cortical bone thickness and bone density were significantly smaller in smokers than nonsmokers. Cortical bone thickness and bone density were significantly lower after than before treatment in both smokers and nonsmokers.

CONCLUSION

In addition to all of its known dangers, cigarette smoking may also harm the alveolar bone by decreasing the bone thickness and density during orthodontic treatment in heavy smokers.

Vertical Control of a Severe Hyperdivergent Skeletal Class II Malocclusion with Steep Posterior Occlusal Plane in a Camouflage Case

Severe hyperdivergent skeletal Class II malocclusion may be ideally treated with orthognathic surgery in adult patients. Here, we report a camouflage treatment of a 23-year-old female patient. She was diagnosed with a skeletal Class II malocclusion with extreme high mandibular plane angle, retrusive mandible, steep posterior occlusal plane, anterior open bite, and severe overjet. The treatment plan included extraction of all second premolars and intrusion of the maxillary anterior teeth and mandibular posterior teeth using miniscrews. These contributed to an effective counterclockwise rotation of the mandible, decreased lower face height, and improvement in anterior overbite. This case report shows a vertical control strategy on severe hyperdivergent skeletal Class II malocclusions, which achieves well-controlled sagittal and vertical dimensions and a favorable facial appearance. The treatment and retention results were well balanced and aesthetically pleasing.

The Correlation of Mineral Density of Jaws With Skeletal Bone and Its Effect on Implant Stability in Osteoporotic Patients: A Review of Patient-Based Studies

Osteoporosis has been an enigma in terms of the administration of implant therapy. It has been implicated as a cause of implant failure as it directly affects the quality of the bone. The diagnosis of osteoporosis is mainly done by measuring skeletal bone mineral density (BMD). During implant therapy, the BMD of jaws can be evaluated on routine orthopantomogram (OPG) or cone beam CT (CBCT). The various advantages of CBCT include establishing a correlation between skeletal bone density and bone density of jaws and estimating its effect on implant stability in osteoporotic patients, which in turn will help in determining the prognosis of the implant in osteoporotic patients. This review is a summary of all patient-related studies conducted in the mentioned context of implant placement in patients with osteoporosis, treatment modalities, and prognosis. We performed a search of relevant articles on Google Scholar, PubMed, and Cochrane, which yielded a total of 25 articles for full-text reviews. After excluding some articles based on the exclusion criteria, a review was conducted along with a pilot study on implant placement in osteoporotic patients. Regional bone density can be a helpful parameter in predicting primary implant stability and it can be a useful indicator of skeletal BMD. With a careful evaluation of BMD, dental implants can be placed in patients with osteoporosis with a better prognosis for the treatment.

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 Effect of Under-Drilling and Osseodensification Drilling on Low-Density Bone: A Comparative Ex Vivo Study

The aim of this study is to identify a method that can maximize implant primary stability (IPS) and bone density under the controlled drilling conditions of the same diameter and length in low-density bones through an ex vivo study. A total of 87 dental implants were placed with standard drilling, under-drilling, and osseodensification drilling in 13 fresh porcine sternums. The Periotest value and the implant stability quotient were measured to evaluate the primary stability. The difference in the Hounsfield unit (HU) between the hole and peripheral bone up to a distance of 1 mm was measured. Osseodensification and under-drilling technique increased the IPS, compared with conventional drilling technique with statistical significance under the drilling conditions of the same diameter and length. Osseodensification technique with the counter-clockwise direction had higher HU gaps than the standard drilling and osseodensification technique with clockwise direction. Due to the effect of bone densification, the gap of HU was increased by a minimum of 43 HU and a maximum of 180 HU. Within the limitations of this ex vivo study, it was found that the osseodensification technique with counter-clockwise direction is effective to increase IPS and bone mineral density in low-density bone.

Clinical evaluation of 3D printed nano-porous hydroxyapatite bone graft for alveolar ridge preservation: A randomized controlled trial

Background/purpose

Ridge resorption after tooth extraction may result in inadequate bone volume and unfavorable ridge architecture for ideal implant placement. The use of bone substitutes has been advocated to fill extraction sites and to enhance primary implant stability. This study was made to evaluate the clinical efficacy of novel 3D printed nano-porous hydroxyapatite (3DP HA, test group) in comparison to nano-crystalline bone graft (NanoBone®, control group) in alveolar ridge preservation prior to implant placement.

Materials and methods

Thirty patients were randomized into two groups following tooth extraction. All extracted sockets were filled with 3DP HA or NanoBone® and covered with a non-resorbable membrane. After four months, cone-beam computed tomography (CBCT) and intraoral scanner were used to measure dimensional changes of bone and soft tissue surface. Bone core specimens were harvested for histological analysis during implant osteotomy. Implant stability was assessed using a modified damping capacity analysis.

Results

At four months postoperatively, dimensional changes in soft tissue surface resorption were less in the test group than in the control group; however, alveolar bone resorption was the same in both groups. Histological analysis revealed new bone formation, residual graft and fibrous connective tissue in both groups. The average primary implant stability (IST) value for both groups was approximately 70. There was no statistically significant difference in all parameters between two groups (p > 0.05).

Conclusion

3DP HA could potentially be used as an alternative bone graft material for alveolar ridge preservation.

Can gray values be converted to Hounsfield units? A systematic review

OBJECTIVES

The purpose of this systematic review was to answer the focus question: "Could the gray values (GVs) from CBCT (cone beam computed tomography) be converted to Hounsfield units (HUs) in multidetector computed tomography (MDCT)?"

METHODS

The included studies try to answer the research question according to the PICO strategy. Studies were gathered by searching several electronic databases and partial grey literature up to January 2021 without language or time restrictions. The methodological assessment of the studies was performed using The Oral Health Assessment Tool (OHAT) for in vitro studies and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) for in vivo studies. The Grading of Recommendations Assessment, Development and Evaluation (GRADE system) instrument was applied to assess the level of evidence across the studies.

RESULTS

2710 articles were obtained in Phase 1, and 623 citations remained after removing duplicates. Only three studies were included in this review using a two-phase selection process and after applying the eligibility criteria. All studies were methodologically acceptable, although in general terms with low risks of bias. There are some included studies with quite low and limited evidence estimations and recommendation forces; evidencing the need for clinical studies with diagnostic capacity to support its use.

CONCLUSIONS

This systematic review demonstrated that the GVs from CBCT cannot be converted to HUs due to the lack of clinical studies with diagnostic capacity to support its use. However, it is evidenced that three conversion steps (equipment calibration, prediction equation models, and a standard formula (converting GVs to HUs)) are needed to obtain pseudo Hounsfield values instead of only obtaining them from a regression or directly from the software.

The Effect of Bone Density Measured by Cone Beam Computed Tomography and Implant Dimensions on the Stability of Dental Implants

ABSTRACT

The aim of this study was to evaluate the effect of bone density value in Hounsfield unit derived from cone beam computed tomography (CBCT), and implant dimensions in relation to implant stability parameters namely the resonance frequency analysis and the insertion torque (IT) value. It included 24 patients who received 42 dental implants (DI). The bone density of the planned implant site was preoperatively measured using cone beam computed tomography. The implant stability was measured using Osstell implant stability quotient (ISQ). The ISQ values were recorded immediately postoperatively and after 16 weeks. The IT value was categorized as 35 N/cm or > 35 N/cm. The mean (standard deviation) primary stability was 79.58 (5.27) ISQ, which was significantly higher than the secondary stability 74.31 (6.34) ISQ (P < 0.0001). There was a significant moderate positive correlation of bone density with primary stability (r = 0.4, P = 0.0099) and no correlation with secondary stability (r = 0.003, P = 0.9867). The bone density of DI with 35 N/cm IT was significantly lower than with > 35 N/cm IT (P = 0.0390). Better stability was recorded with wider implants. Whereas the length of the DI showed a nonsignificant correlation with primary and secondary stability (P = 0.7633 and 0.4670, respectively). The DI dimensions showed a nonsignificant correlation with the IT. Cone beam computed tomography may be considered as a reliable method to assess bone density and predict the implant stability. The diameter of DI affected the implant stability favorably, whereas DI length showed no effect.

Small blood stem cells for enhancing early osseointegration formation on dental implants: a human phase I safety study

Background

Small blood stem cells (SB cells), isolated from human peripheral blood, demonstrated the ability to benefit bone regeneration and osseointegration. The primary goal of our study is to examine the safety and tolerability of SB cells in dental implantation for human patients with severe bone defects.

Methods

Nine patients were enrolled and divided into three groups with SB cell treatment doses of 1 × 10⁵, 1 × 10⁶, and 1 × 10⁷ SB cells, and then evaluated by computed tomography (CT) scans to assess bone mineral density (BMD) by Hounsfield units (HU) scoring. Testing was conducted before treatment and on weeks 4, 6, 8, and 12 post dental implantation. Blood and comprehensive chemistry panel testing were also performed.

Results

No severe adverse effects were observed for up to 6-month trial. Grade 1 leukocytosis, anemia, and elevated liver function were observed, but related with the patient’s condition or the implant treatment itself and not the transplantation of SB cells. The levels of cytokines and chemokines were detected by a multiplex immunological assay. Elevated levels of eotaxin, FGF2, MCP-1, MDC, and IL17a were found among patients who received SB cell treatment. This observation suggested SB cells triggered cytokines and chemokines for local tissue repair. To ensure the efficacy of SB cells in dental implantation, the BMD and maximum stresses via stress analysis model were measured through CT scanning. All patients who suffered from severe bone defect showed improvement from D3 level to D1 or D2 level. The HU score acceleration can be observed by week 2 after guided bone regeneration (GBR) and prior to dental implantation.

Conclusions

This phase I study shows that treatment of SB cells for dental implantation is well tolerated with no major adverse effects. The use of SB cells for accelerating the osseointegration in high-risk dental implant patients warrants further phase II studies.

Trial registration

Taiwan Clinical Trial Registry (SB-GBR001) and clinical trial registry of the United States (NCT04451486).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02461-z.

Bone Density around Titanium Dental Implants Coating Tested/Coated with Chitosan or Melatonin: An Evaluation via Microtomography in Jaws of Beagle Dogs

Peri-implant bone density plays an important role in the osseointegration of dental implants. The aim of the study was to evaluate via micro-CT, in Hounsfield units, the bone density around dental implants coated with chitosan and melatonin and to compare it with the bone density around implants with a conventional etched surface after 12 weeks of immediate post-extraction placement in the jaws of Beagle dogs. Six dogs were used, and 48 implants were randomly placed: three groups—melatonin, chitosan, and control. Seven 10 mm × 10 mm regions of interest were defined in each implant (2 in the crestal zone, 4 in the medial zone, and 1 in the apical zone). A total of 336 sites were studied with the AMIDE tool, using the Norton and Gamble classification to assess bone density. The effect on bone density of surface coating variables (chitosan, melatonin, and control) at the crestal, medial, and apical sites and the implant positions (P2, P3, P4, and M1) was analyzed at bivariate and multivariate levels (linear regression). Adjusted effects on bone density did not indicate statistical significance for surface coatings (p = 0.653) but did for different levels of ROIs (p < 0.001) and for positions of the implants (p = 0.032). Micro-CT, with appropriate software, proved to be a powerful tool for measuring osseointegration.

Texture analysis of cone beam computed tomography images reveals dental implant stability

The aim of this study was to characterize the alveolar bone of edentulous maxillary sites using texture analysis (TA) of cone beam computed tomography (CBCT) images and to correlate the results to the insertion torque, thus verifying whether TA is a predictive tool of final implant treatment. This study was conducted on patients who had received single implants in the maxilla (46 implants) 1year earlier and whose torque values were properly recorded. Three cross-sections of the sites were selected on CBCT scans. Two regions of interest (ROIs) corresponding to the implant bone site and peri-implant bone were also outlined, according to virtual planning. The CBCT scans were exported to MaZda software, where the two ROIs were delimited following the previously demarcated contours. Values for the co-occurrence matrix were calculated for TA. With regard to the insertion torque value, there was a direct correlation with the contrast of the peri-implant bone (P<0.001) and an inverse correlation with the entropy of the implant bone site (P=0.006). A greater contrast indicates a greater torque value for insertion of the implants, and there is a possible association with a lower entropy value of the implant-bone interface.

Quantifying Bone Quality Using Computed Tomography Hounsfield Units in the Mid-sagittal View of the Lumbar Spine

BACKGROUND

Computed tomography Hounsfield unit (HU) is an alternative tool to the dual energy x-ray absorptiometry scan T-score to quantify the bone quality. DEXA scan can overestimate the bone mineral density. We studied the correlation of the vertebral mid-axial and mid-sagittal HU to the T-score.

METHODS

We retrospectively reviewed the electronic medical records of patients who underwent dual energy x-ray absorptiometry and computed tomography scans within 1 year. Age, sex, mid-axial and mid-sagittal HU, and T-score were collected and statistically analyzed.

RESULTS

We identified 100 patients with computed tomography of the L1-L4. There were 80 female and 20 male patients. The average age was 60.25 years (±12.54 years). Nineteen patients were diagnosed with degenerative spine disease. There were 56 patients with a normal T-score, 33 with osteopenia, and 11 with osteoporosis. The average HU for the mid-sagittal view was 163 (±59) for L1, 159 (±62) for L2, 151 (±59) for L3, and 150 (±62) for L4. The mid-axial and mid-sagittal HU were positively correlated to the DEXA T-score (P < 0.001). The HU was 177 (95% CI: 160-194) for normal T-scores, 132 (120-143) for T-scores indicating osteopenia, and 106 (88-124) for T-scores indicating osteoporosis (P < 0.001). Post hoc analysis showed no difference between osteopenia and osteoporosis (P = 0.46).

CONCLUSIONS

Mid-sagittal HU is positively correlated to the T-score, similar to the mid-axial HU. Therefore, it can be used to acquire a general overview of the bone quality before spinal instrumentation.

Multivariate analysis of the influence of peri-implant clinical parameters and local factors on radiographic bone loss in the posterior maxilla: a retrospective study on 277 dental implants

OBJECTIVES

The aim of the present study was to investigate whether peri-implant clinical parameters (modified plaque index (mPI), bleeding and/or suppuration on probing (B/SOP)) and local factors (type of prostheses, screw emergence, platform diameter, and abutment angulation) might contribute to the development of additional bone loss and peri-implantitis around dental implants.

MATERIALS AND METHODS

Two hundred seventy-seven external hex connection implants placed in the posterior maxilla of 124 patients were retrospectively evaluated. They were divided into two groups: physiologic bone loss < 2 mm (PBL) or additional bone loss ≥ 2 mm (ABL). GEE logistic regression was applied to evaluate the influence of type of prostheses (implant-supported single crown (ISSC), fixed partial denture (ISFPD), and full denture (ISFD)) and clinical parameters (mPI and S/BOP) on bone loss.

RESULTS

Among the 277 implants, 159 (57.4%) presented PBL and 118 (42.6%) presented ABL. Within the ABL group, 20.6% implants were diagnosed with peri-implantitis. mPI significantly correlated with the type of prosthesis and the highest value of mPI (index = 3) was observed in ISFD (23.8%). Moreover, peri-implantitis was more frequently associated with ISFD (32.79%) than ISSC and ISFDP (13.79% and 13.48, respectively) CONCLUSIONS: ISFD in the posterior maxilla presented high rates of ABL and showed a higher prevalence of peri-implantitis. None of the local factors seemed to contribute to the development of these conditions. Further investigations are needed to prospectively support the results of the present study.

CLINICAL RELEVANCE

Patients rehabilitated with ISFD should be carefully monitored and have more frequent maintenance visits to prevent or control peri-implant bone loss.

Methodological quality and risk of bias of systematic reviews about loading time of multiple dental implants in totally or partially edentulous patients: An umbrella systematic review

BACKGROUND

There are several systematic reviews of multiple implant loading techniques, but results are conflicting.

AIM

To perform an umbrella review on methodological quality of systematic reviews about techniques for loading multiple dental implants.

MATERIAL AND METHODS

MEDLINE (PubMed) and Scopus were searched up to December 31, 2019. Unpublished literature was searched through OpenGray and references of included articles were manually verified. Eligibility criteria were: articles had to (1) be about multiple dental implants; (2) mention the moment of loading; (3) be a systematic review. Two independent reviewers participated in the entire process. Qualitative description of included studies as well as methodological quality measurement and risk of bias through AMSTAR and ROBIS were performed.

RESULTS

21 reviews were included. Thirteen stated that there was a similarity between loading techniques, two did not affirm which one was more appropriate and six mentioned that conventional technique was better. Eight papers were classified as high risk of bias, twelve as low and one as uncertain risk.

CONCLUSION

When evaluating only studies with a low risk of bias, there are no significant differences in implant loading time.

Design of dental implant using design of experiment and topology optimization: A finite element analysis study

Ever since the introduction of topology optimization into the industrial and manufacturing fields, it has been a top priority to maximize the performance of any system by optimizing its geometrical parameters to save material while keeping its functionality unaltered. The purpose of this study is to design a dental implant macro-geometry by removing expendable material using topology optimization and to evaluate its biomechanical function. Three-dimensional finite element models were created of an implant embedded in cortical and cancellous bone. Parameters like the length and diameter of the implant and the bone quality (±20% variation in Young’s modulus, Poisson’s ratio and density for both cortical and cancellous bone) were varied to evaluate their effect on the principal stresses induced on the peri-implant bone tissues and the micromotion of the implant at 150 N applied load. Design optimization is used to select one suitable implant for each material property combination with optimum parameters that experiences the least von Mises stress and axial deformation, out of twenty implants with different length and diameter for each material property combination. Topology optimization was then used on the selected implants to remove the redundant material. The biomechanical functions of the implants with optimized parameter and volume were then evaluated. The finite element analyses estimated that a reduction of 32% to 45% in the implant volume is possible with the implant still retaining all of its functionality.

Effect of enamel matrix derivative on alveolar ridge preservation in the posterior maxilla: A randomized controlled clinical trial

BACKGROUND

EMD has been considered to exert positive effects on wound healing, postoperative discomfort, and bone regeneration.

PURPOSE

The aim of this randomized controlled clinical trial was to investigate and compare (a) horizontal and vertical bone dimensional changes, (b) early postoperative discomfort and soft tissue wound healing outcomes, and (c) treatment modalities for implant placement, following posterior maxillary alveolar ridge preservation (ARP) with and without adjunctive use of EMD.

METHODS

Twenty-eight participants were randomly assigned to three groups: extraction sockets filled with bovine bone mineral and membrane with EMD (test group 1, n = 10) and without EMD (test group 2, n = 10) and spontaneous healing (control group, n = 8). Alveolar bone dimensional changes were measured using cone-beam computed tomography 5 months after ARP, and postoperative pain and wound healing outcomes were also evaluated.

RESULTS

There were no significant differences in horizontal or vertical bone dimensional changes between test groups 1 (horizontal width changes at 1 mm apically below the alveolar ridge crest [HW]: -1.44 ± 0.54 mm) and 2 (HW: -1.42 ± 0.26 mm), but the changes at HW (-2.36 ± 1.03 mm) in the control group were significantly greater than those in test groups 1 and 2 (P < .05). Early postoperative discomfort and soft tissue wound healing outcomes were not significantly different between the two test groups. Furthermore, unlike the control group, both the test groups 1 and 2 were implanted without sinus floor elevation using the lateral approach.

CONCLUSION

Within the limitations of this study, EMD failed to provide additional benefits in ARP in the posterior maxilla.

Revascularized Fibula Free Flap Reconstruction and Curvilinear Transport Distraction Osteogenesis in Closure of Large Postmaxillectomy Defects: A New Gold Standard?

Introduction:

The revascularized fibula free flap (RFFF) is the most popular method of postmaxillectomy reconstruction. This article proves that the use of curvilinear transport distraction osteogenesis (CTDO) is an efficacious way in closing large defects in the maxilla and a superior alternative to the RFFF.

Methods and Materials:

In a prospective cohort study of six postmaxillectomy patients, CTDO was applied and the new bone (regenerate) was compared with the parent bone from which it had been regenerated. These results were compared with a retrospective group of six participants of similar age and sex who had undergone RFFF reconstruction as an external control. Clinical measurements taken at the depth of the alveolar vestibule were recorded at three different exact points juxtaposed, namely (A) lateral incisor, (B) first premolar, and (C) first molar. These areas of interest were similar to those chosen on the CT scans. Impressions were taken from all the patients and stone casts were made. The width of the alveolar bone was computed based on the measurements made from the stone casts. The stone casts were then used to calculate the width and depth of the soft tissue and bone in the maxilla in the (A), (B), and (C) regions.

Results:

The regenerate possessed anatomical and physiological characteristics equal to the parent bone. For the CTDO patients, prosthetic rehabilitation of the dentition was supported by dental implants after osseointegration of the latter into the newly created bone and soft tissue.

Discussion:

The production of the curvilinear bone and soft tissue along a horizontal plane has been demonstrated. The new alveolar bone achieved the correct width and depth to create a physiological vestibule and a functional/esthetic zone for the placement of dental implants. In addition, the shape of the palatal vault was also maintained. The CTDO method is a reliable method of maxillary reconstruction and has a better anatomical and functional outcome than the RFFF.

Comparison of histomorphometry and microradiography of different implant designs to assess primary implant stability

OBJECTIVES

To contribute toward optimizing the long-term stability of dental implants. Our working hypothesis was that the degrees of immediate implant-bone contact, and hence of primary stability, would demonstrably differ between implant systems due to their different external geometries and thread designs (macro-design). This demonstration was provided in a bovine model (ex vivo) by employing and comparing histomorphometry and microradiography as evaluation methods.

MATERIALS AND METHODS

A total of 120 implants, representing six different implant thread designs, were inserted following the recommended surgical protocol in ribs of freshly slaughtered cattle. Twenty specimens of implants with surrounding bone were prepared per system and were divided into two equally sized groups of 60 specimens for analysis by either histomorphometry or micro-computed tomography. Data were analyzed by Mann-Whitney U test (P ≤ .05).

RESULTS

One of the implant systems, featuring a slight tapered external geometry and a progressive thread design, consistently revealed the most favorable bone-implant contacts in both histomorphometric and microradiographic evaluations. Overall, consistently higher values of bone-implant contact were obtained with the microradiographic than the histomorphometric approach, and this difference reached statistical significance in three of the six implant systems tested.

CONCLUSIONS

Progressive threads offering a bone-condensing effect can significantly help to maximize implant-bone contact percentages. Compared to histomorphometry, microradiography is likewise a suitable method to evaluate bone-implant contact, offering the additional benefits of being noninvasive and less time consuming.

Image-based Bone Density Classification Using Fractal Dimensions and Histological Analysis of Implant Recipient Site

Background:

Success of dental implants is affected by the quality and density of the alveolar bone. These parameters are essential for implant stability and influence its load-bearing capacity. Their assessment is usually based on preoperative radiographs used as a tool prior to implant procedures.

Objective:

The aim of the study was to compare the bone density of surgically harvested bone specimens at implant recipient sites in the maxillary and mandibular posterior region using histological analysis to the radiographic bone density using fractal dimension for reliability and determining an image based classification of bone density prior surgery.

Methods:

Fifty implants were placed in the posterior region of male patients, (twenty five implants in the maxilla and twenty five in the mandible). The edentulous regions were presurgically assessed using Photo Stimulable Phosphor Plate (PSP) intra-oral radiographs and the fractal dimension box counting of region of interest was calculated at the implant recipient site. During surgery, bone core specimens were trephined, and bone densities and minerals parameters were evaluated based on histological analysis using SEM (Scanning Electron Microscopy), and atomic absorption spectrometry.

Results:

Fractal dimensions (FD) values for the same region of interest (ROI) selected on the radiographs of bone blocks and edentulous sites were different but showed a proportional variation in molar and premolar region of the maxilla and mandible. Bone density results, calculated by the ratio of bone mass (BM) to the bone volume (BV) of the bone core specimen (D=M/V), increased in the mandibular bone blocks, and decreased in the maxilla specimens. Moreover, fractal dimension values of preoperative radiographs at implant recipient sites and bone density of trephined showed a statistically similar distribution. However, no significant difference was shown in the percentage of minerals contents and mass of calcium phosphate of each bone specimen between maxilla and mandible based on scanning electron microscopy analysis. Four types of bone densities were classified according to the distribution of FD values based on preoperative radiographs and on the densities of bone cores calculations.

Conclusion:

Radiographic estimation of bone quality calculated with fractal dimension could be a useful, non-invasive tool when using preoperative intra-oral radiographs to predict bone density at implant recipient sites with caution and limits concerning the kind of digital radiographs and size of region of interest, especially when these results were based with bone specimens harvested from implant site as an absolute reference.

A clinical pilot study of jawbone mineral density measured by the newly developed dual-energy cone-beam computed tomography method compared to calibrated multislice computed tomography

Purpose

This clinical pilot study was performed to determine the effectiveness of dual-energy cone-beam computed tomography (DE-CBCT) in measuring bone mineral density (BMD).

Materials and Methods

The BMD values obtained using DE-CBCT were compared to those obtained using calibrated multislice computed tomography (MSCT). After BMD calibration with specially designed phantoms, both DE-CBCT and MSCT scanning were performed in 15 adult dental patients. Three-dimensional (3D) Digital Imaging and Communications in Medicine data were imported into a dental software program, and the defined regions of interest (ROIs) on the 3-dimensional surface-rendered images were identified. The automatically-measured BMD values of the ROIs (g/cm³), the differences in the measured BMD values of the matched ROIs obtained by DE-CBCT and MSCT 3D images, and the correlation between the BMD values obtained by the 2 devices were statistically analyzed.

Results

The mean BMD values of the ROIs for the 15 patients as assessed using DE-CBCT and MSCT were 1.09±0.07 g/cm³ and 1.13±0.08 g/cm³, respectively. The mean of the differences between the BMD values of the matched ROIs as assessed using DE-CBCT and calibrated MSCT images was 0.04±0.02 g/cm³. The Pearson correlation coefficient between the BMD values of DE-CBCT and MSCT images was 0.982 (r=0.982, P<0.001).

Conclusion

The newly developed DE-CBCT technique could be used to measure jaw BMD in dentistry and may soon replace MSCT, which is expensive and requires special facilities.

Distribution of Trabecular Bone Density in the Maxilla and Mandible

INTRODUCTION

Implant osseointegration is strongly influenced by the bone quality at the implant insertion site. The present work aims to create distribution diagrams showing the average bone density at each position within the jaws.

MATERIALS AND METHODS

Data were retrospectively collected from 4 oral surgeons who sought bone-density measurements during implant placement using a torque-measuring implant micromotor. Statistical analyses were performed to investigate whether bone density correlated with the patients' sex and age and whether the bone-density values at different positions within each arch correlated to each other.

RESULTS

Records of 2408 patients and 6060 bone-density readings were retrieved, and density distribution diagrams were created. Density values showed a significant variation within subjects. Within the same jaw, density between adjacent positions showed significant differences. Density at a given position correlated significantly with that at the other positions in most cases. Bone density was significantly lower in women than in men; no significant correlation was found between bone density and the patient age.

CONCLUSIONS

Bone density of patients displays significant interindividual variation, thus meaningful assessment must be conducted on a patient-by-patient basis.

A Novel Approach for Horizontal Augmentation of Posterior Maxilla Using Ridge Split Technique

Over the years, there have been a series of innovative approaches to the alveolar bone augmentation techniques. These have led to the modifications of the existing methods and the establishment of more efficient ways to obtain sufficient bone mass that is necessary for the implant procedure. The aim of this paper is to propose a novel augmentation technique, and to investigate its efficacy, particularly during the healing process of the maxillary alveolar bone prior to the implant treatment. During the application of the proposed methodology, first, the ridge-split technique was applied to the posterior maxilla. Then, a horizontal augmentation procedure was performed with an autogenous bone graft. Implants were placed at the second month of the surgery. Prosthetic rehabilitation was completed after the osseointegration of the implants. The technique was compared with the ridge-split method with simultaneous implant placement in 14 patients. The groups were divided into 2, the control group and the experimental group, each containing 7 patients. The aimed success criteria for the status of the endosteal implants were fulfilled and there were not any complications observed in the second year of follow-up.The basic practical innovation offered by the proposed surgical technique is to achieve the required horizontal dimension and to change the quality of the bone conveniently. The press-fit insertion leads to multipoint contact healing of the transported bone and the use of cortical block bone in posterior maxilla, led to a significantly advantageous higher stability level for both the placement and the survival of the implants.

Radiographic changes of trabecular bone density after loading of implant-supported complete dentures: A 3-year prospective study

BACKGROUND

Bone tissues may undergo remodeling under functional mechanical stimuli.

PURPOSE

This prospective study on implant-supported fixed complete dentures (IFCDs) evaluated the radiographic trabecular bone changes in density by means of gray levels and texture analysis variables after up to 3-year loading.

MATERIALS AND METHODS

The sample consisted of digital periapical radiographs of 63 distal implants of hybrid IFCDs installed in 30 patients (22 women, mean age of 62 ± 7.8 years). Digital periapical radiographs were taken after prosthesis installation, and 1 and 3 years after IFCD loading. Longitudinal images of each implant were superimposed, and the same regions of interest were selected for measurement of gray levels statistics (mean gray levels, SD, and coefficient of variation [CV]) and texture parameters (correlation, contrast, entropy, and angular second moment). Data were analyzed by mixed regression models.

RESULTS

Mean gray levels increased for 1 year (P < .05), for 3 years (P < .01) and for maximum bite force (P < .01). The interaction between bruxism and time in 1 year was significant (P < .01) for a decrease in CV. No significant effect of texture analysis variables was found (P > .05).

CONCLUSIONS

The results suggest an increase of radiographic bone density as measured by an increase in mean gray levels and a decrease in CV in IFCD distal implants up to 3 years of loading.

Hounsfield Units on Lumbar Computed Tomography for Predicting Regional Bone Mineral Density

Objective

Bone mineral density (BMD) is a very important factor in spinal fusion surgery using instrumentation. Our aim was to investigate the utility of Hounsfield units (HU) obtained from preoperative lumbar computed tomography (CT) to predict osteoporosis coupling with data of quantitative computed tomography (QCT) and dual X-ray absorptiometry (DEXA).

Methods

We reviewed 180 patients that underwent both QCT and lumbar CT for spine surgery. HU was retrospectively calculated on the lumbar CT of 503 lumbar vertebrae from L1 to L3. Femur DEXA was performed in all patients and spine DEXA was tested in 120 patients (331 vertebrae). BMD was grouped as osteoporosis (QCT<80mg/cm³, DEXA T score≤-2.5) and non-osteoporosis (QCT≥80mg/cm³, DEXA T score>-2.5) for comparison of HU value.

Results

HU value and BMD showed significant correlations. The optima cut-off value based on QCT was higher than that of DEXA scans which had the best correlation for predicting osteoporosis. ROC curve analysis demonstrated that HU value with QCT of 146 has a sensitivity of 94.3% and a specificity of 87.5% for osteoporosis.

Conclusions

Significant correlation was found between HU measurement and BMD value. These findings provide evidence that HU measurement can be established as a means for predicting osteoporosis before spine fusion surgery with reduced radiation hazard.

Feasibility of Assessing Maxillary and Mandibular Bone Mineral Density for Dental Implantation by Using Multidetector Computed Tomography

PURPOSE

The purpose of this study was to evaluate the feasibility of measuring bone mineral density (BMD) of the maxillary and mandibular bones for dental implantation by using multidetector computed tomography (MDCT).

MATERIALS AND METHODS

We performed MDCT in 141 patients (78 women and 63 men) at the lumbar vertebrae and at the maxillary and mandibular bones, with a view to dental implantation, from July 2015 to June 2017. Quantitative CT (QCT) using MDCT was performed to obtain Hounsfield unit (HU) values for the maxillary and mandibular bones and to obtain T scores for the lumbar vertebrae. We statistically analyzed the relationships among HU values, and the correlations of QCT values with T scores and of T scores with HU values.

RESULTS

There were statistically significant correlations among all these parameters.

CONCLUSIONS

QCT using MDCT of the maxillary and mandibular bones seems to be a feasible method for measuring BMD before dental implantation.

Immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing for failing teeth in the maxillary molar area: A randomized controlled trial clinical study with one-year follow-up

BACKGROUND

In previous studies, immediate implant placement in molar sites has been widely applied.

PURPOSE

To study the clinical effect and feasibility of immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing for failing teeth in the maxillary molar area.

MATERIAL AND METHODS

Patients who required implantation surgry to replace a failing tooth in the maxilla molar region were selected. Patients were randomized into two groups: immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing (test group) or delayed implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing (control group). The outcome criteria were the success rates of implants, Cone Beam Computer Tomography (CBCT) data and results of the subjective satisfaction survey performed with a visual analog scale (VAS).

RESULTS

All implants had good initial stability after implantation. The survival rate of implants was 100% at 1-year follow-up. At the time of permanent restoration, the differences in average horizontal shrinkage of alveolar bone (W1) on the buccal side between the test group (0.65 ± 0.12 mm) and the control group (1.23 ± 0.32 mm) were statistically significant (P < .0001); however, no statistically significant difference (P = .515) was observed on the palatal side (0.3 ± 0.10 mm vs 0.28 ± 0.08 mm). The difference in vertical resorption of alveolar bone (H1) on the buccal side between the test group (0.60 ± 0.18 mm) and the control group (1.53 ± 0.19 mm) was statistically significant (P < .0001), but no statistically significant difference (P = .190) in the reduction of palatal alveolar bone (0.24 ± 0.12 mm vs 0.29 ± 0.13 mm) was observed. After 1-year loading, no statistically significant difference (P > .05) in vertical or horizontal changes (W2, H2) were identified in the test group or control group. Patient satisfaction in both groups was similar (8.36 ± 1.01 vs 8.14 ± 1.35), and the difference between groups was not statistically significant (P = .638).

CONCLUSION

Immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing is feasible for the maxillary molar area, and the clinical effect is satisfactory.

Periprosthetic biomechanical response towards dental implants, with functional gradation, for single/multiple dental loss

The differences in shape and stiffness of the dental implants with respect to the natural teeth (especially, dental roots) cause a significant alteration of the periprosthetic biomechanical response, which typically leads to bone resorption and ultimately implant loosening. In order to avoid such clinical complications, the implant stiffness needs to be appropriately adapted. In this study, hollow channels were virtually introduced within the designed implant screws for reduction of the overall stiffness of the prototype. In particular, two opposing radial gradients of increasing hollow channel diameters, i.e., outside to inside (Channel 1) and inside to outside (Channel 2) were considered. Two clinical situations of edentulism were addressed in this finite element-based study, and these include a) loss of the first molar, and b) loss of all the three molars. Consequently, two implantation approaches were simulated for multiple teeth loss - individual implantation and implant supported dental bridge. The effects of implant length, approach and channel distribution on the biomechanical response were evaluated in terms of the von Mises stress within the interfacial periprosthetic bone, under normal masticatory loading. The results of our FE analysis clearly reveal significant variation in periprosthetic bone stress between the different implant designs and approaches. An implant screw length of 11 mm with the Channel 2 configuration was found to provide the best biomechanical response. This study also revealed that the implant supported dental bridge approach, which requires lower bone invasion, results in favorable biomechanical response in case of consecutive multiple dental loss.

The evaluation of implant stability measured by resonance frequency analysis in different bone types

Objectives

Bone density seems to be an important factor affecting implant stability. The relationship between bone density and primary and secondary stability remains under debate. The aim of this study was to compare primary and secondary stability measured by resonance frequency analysis (RFA) between different bone types and to compare implant stability at different time points during 3 months of follow-up.

Materials and Methods

Our study included 65 implants (BioHorizons Implant Systems) with 3.8 or 4.6 mm diameter and 9 or 10.5 mm length in 59 patients. Bone quality was assessed by Lekholm-Zarb classification. After implant insertion, stability was measured by an Osstell device using RFA at three follow-up visits (immediately, 1 month, and 3 months after implant insertion). ANOVA test was used to compare primary and secondary stability between different bone types and between the three time points for each density type.

Results

There were 9 patients in type I, 18 patients in type II, 20 patients in type III, and 12 patients in type IV. Three implants failed, 1 in type I and 2 in type IV. Stability values decreased in the first month but increased during the following two months in all bone types. Statistical analysis showed no significant difference between RFA values of different bone types at each follow-up or between stability values of each bone type at different time points.

Conclusion

According to our results, implant stability was not affected by bone density. It is difficult to reach a certain conclusion about the effect of bone density on implant stability as stability is affected by numerous factors.

Association between Marginal Bone Loss and Bone Quality at Dental Implant Sites Based on Evidence from Cone Beam Computed Tomography and Periapical Radiographs

Objective:

The aim of this study was to assess bone quality in patient's preoperative cone beam computed tomography (CBCT) and their relation with marginal bone loss at implant placement sites over follow-up periods.

Materials and Methods:

In this retrospective cross-sectional study, 100 implants were evaluated. The implants had been placed in the maxillary and mandibular edentulous areas. Bone quality at implant placement sites was measured on preoperative CBCTs and then classified by two observers according to Lekholm and Zarb classification. Marginal bone height was then measured on periapical radiographs obtained at baseline and then 6, 12, 18, 24, and 30 months’ follow-up periods from a reference point (implant shoulder) to the bone-implant interface. The relation between bone quality and bone loss was assessed. ANOVA was used to compare mean difference among groups and Pearson correlation coefficient to assess the correlation between observers. All statistical analyses were performed at 0.05 significance level using Stata 11 software (StataCorp, College Station, TX, USA).

Results:

Of 100 implants, 48 were placed in the maxilla and 52 in the mandible. There was no significant difference between bone quality and the mean bone loss at follow-up periods. Using Pearson's correlation coefficient, it was shown that with an increase in bone quality, marginal bone loss was decreased at follow-up periods.

Conclusions:

The results confirmed that during the follow-up periods, less bone loss was observed in implant areas with higher bone quality and CBCT is a reliable tool for assessing bone quality at implant placement sites and estimation of subsequent treatment prognosis.

Study on bone quality in the human mandible-Alignment of biological apatite crystallites

The importance of considering bone quality during oral implant treatment is increasingly being recognized. Assessment of bone quality in response to changes in the jaw bone is extremely important when planning treatment. The present study analyzed biological apatite (BAp) crystallites, a bone quality factor, in order to investigate crystallographic anisotropy in dentate and edentulous human mandibles. Using mandibular samples from Japanese adult cadavers, a region of interest was established comprising cortical bone in the central incisors. Samples were classified into five morphological categories based on the extent of bone resorption. Bone mineral density (BMD) was measured and diffraction intensity ratios were calculated using a microbeam X-ray diffraction system. While no differences were observed in BMD, differences were observed in BAp crystallite alignment between the measurement points. In the alveolar region, samples with residual alveolar bone showed strong alignment in the occlusal direction, while samples with marked alveolar bone resorption had preferential alignment in the mesiodistal direction. The present findings suggest that tooth loss and the extent of alveolar bone resorption affects bone quality in the mandible. © 2018 Wiley Periodicals, Inc. J. Biomed. Mater. Res. Part B: 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 838-846, 2019.

Osteoporosis effect on posterior mandible in preimplanted area for postmenopausal females using cone-beam computed tomography

Background:

Hormonal changes in women affect bone mineral density, especially during and postmenopausal years, which leads to susceptibility to osteoporosis which interfere with implantation.

Aims:

This study aims to use cone-beam computed tomography (CBCT) viewer program to predict patients with osteoporosis which may decrease the success rate of implantation and to evaluate osteoporosis effect on the posterior mandible.

Settings and Design:

This cross-sectional study consists of 60 Iraqi females who were divided into three groups: Group 1 consisted of 20 nonosteoporotic females aged 20–30 years as a control group, Group 2 consisted of 20 nonosteoporotic females aged 50 years and above, and Group 3 consisted of 20 osteoporotic females aged 50 years and above.

Materials and Methods:

The posterior mandibular first molar area was examined for alveolar bone height and radiographic density (RD) using CBCT.

Statistical Analysis Used:

Statistical analysis was computer assisted using the Statistical Package for the Social Sciences (SPSS version 21). Interclass correlation coefficient was used for calibration. Normally distributed variables were assessed using one-way ANOVA, and Dunnett test with control and not normally distributed were assessed by Kruskal–Wallis test, and multiple Mann–Whitney U-test with Bonferroni adjustment.

Results:

RD showed a significant difference between Group 2 and Group 3 (P = 0.000, MD = 158.554). On the other hand, alveolar bone height showed a significant difference between Group 1 and Group 2 (P = 0.039).

Conclusions:

RD in the posterior mandible first molar area is significantly affected in osteoporotic patients and it can be used as a predictor for the presence of osteoporosis using CBCT.

Implant rehabilitation of the edentulous jaws: Does tilting of posterior implants at an angle greater than 45° affect bone resorption and implant success?: A retrospective study

PURPOSE

This study aimed to (1) investigate the success of posterior implants tilted >45° when 4 immediately loaded implants were used to support full-arch prostheses, eliminating any distal cantilever and (2) examine the effect on marginal bone loss (MBL) of different combinations of anterior multi-unit abutment (MUA) angles and posterior implant tilting angles.

MATERIALS AND METHODS

Records of patients rehabilitated according to the Columbus Bridge Protocol were analyzed. Peri-implant bone levels (PBLs) and MBL were measured for each implant. The influence of posterior implant tilting angle on PBL, MBL, and implant and prosthetic success rate was investigated. The impact on the same endpoints of different anterior MUA angles, and different combinations of anterior MUA and tilted posterior implant angles was also examined.

RESULTS

Records of 41 patients were analyzed, for a total of 46 complete rehabilitations, and 142 implants (52 anterior, 63 posterior tilted ≤45° [group 1], and 27 posterior tilted >45° [group 2]). No implants were lost during the follow-up (25.9 months), and no prosthetic complications were reported. Success rate for posterior implants was 100% in group 1 and 96.3% in group 2. Mean MBL differed significantly between the 2 groups (0.45 mm in group 1, 0.66 in group 2 [P = .04]), but not when the analysis was limited to implants in the same jaw. Implant tilting angle did not correlate with MBL and the MUA angle had no effect on bone resorption around posterior implants, neither in the sample as a whole nor in individual patients.

CONCLUSIONS

Posterior implants tilted >45° to eliminate distal cantilever may be as safe as those tilted less in severely atrophic jaws rehabilitated with immediately loaded, full-arch prostheses supported on 4 implants. Further prospective studies on larger samples of patients and implants and with longer follow-up are needed to confirm these findings.

Tomographic late evaluation of xenogeneic bone grafts in sockets of impacted third molars

It is necessary to preserve height and thickness of the alveolar bone to facilitate rehabilitation with osteointegratable implants or simply to maintain bone integrity after extraction. Biomaterials associated with resorbable or non-resorbable membranes, when placed in the region of the socket, may contribute to avoid this unwanted reabsorption.

Evaluation of Extraction Site Dimensions and Density Using Computed Tomography Treated With Different Graft Materials: A Preliminary Study

PURPOSE

The preliminary human study was designed to evaluate extraction site changes using CT after socket preservation (SP) with different materials.

MATERIALS AND METHODS

Fifty-two sockets from 17 Turkish individuals (8 women and 9 men; mean age 44.70 ± 9.99 years) localized at the maxillary anterior area were treated with demineralized bone matrix + collagen membrane (CM) (N = 14), hydroxyapatite bone substitute (HBS) + CM (N = 14), CM (N = 13), or left empty (N = 11). CT scans were taken 10 and 120 days after the procedure. Horizontal and vertical socket dimensions and Hounsfield unit (HU) values were evaluated.

RESULTS

First 3 groups showed a significant horizontal decrease from day 10 to 120. No significant change was detected in vertical socket dimension. For both horizontal and vertical, no intergroup difference was detected at days 10 and 120. At days 10 and 120, HU values in HBS + CM group were significantly higher compared with others. Apical and coronal HU values were not different at any period.

CONCLUSION

Even if it did not provide better socket dimensions, HBS + CM treatment brought higher tissue density and thus, can be recommended to increase the bone quality and implant success after SP in upper anterior area.

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.

Variations in crestal cortical bone thickness at dental implant sites in different regions of the jawbone

BACKGROUND

Dental implants have become reliable and predictable tools for treating missing teeth. The survival rate of dental implants is markedly influenced by the host bone quality and quantity of the jawbone. A better host bone provides higher initial stability of the dental implant, resulting in better osseointegration and a higher success rate. Host bone quality and quantity are determined by the crestal cortical bone thickness and inner cancellous bone density.

OBJECTIVE

The purpose of this study was to determine the crestal cortical bone thickness at dental implant sites in different regions of the jawbone through the use of dental cone-beam computed tomographic (CBCT) images.

MATERIALS AND METHODS

A total of 661 dental implant sites (81 in the anterior mandible, 122 in the anterior maxilla, 224 in the posterior mandible, and 234 in the posterior maxilla) were obtained from the jawbones of 173 humans. The data were subjected to statistical analysis to determine any correlation between crestal cortical bone thicknesses and jawbone regions using one-way analysis of variance with Tukey's post-test.

RESULTS

The crestal cortical bone thicknesses at dental implant sites in the four regions decreased in the following order: posterior mandible (1.07 ± 0.47 mm, mean ± SD) >anterior mandible (0.99 ± 0.36 mm) >anterior maxilla (0.82 ± 0.30 mm) >posterior maxilla (0.75 ± 0.35 mm).

CONCLUSION

The dental CBCT data demonstrate that crestal cortical bone thickness varies markedly between dental implant sites in the four regions of the jawbone.

Tactile sense of the surgeon in determining bone density when placing dental implant

PURPOSE

To evaluate the bone density using the surgeon's tactile sense and compare it to the Lekholm and Zarb classification and computed tomography (CT) scan to see if correlations exist.

MATERIALS AND METHODS

Fifty-two implants were inserted in 22 patients. The bone densities of recipient site were preoperatively determined by density value as Hounsfield Units (HU) using CT scans. According to the Lekholm and Zarb classification, the bone quality scored 1 to 4 on cross-sectional CT. The clinical hardness of recipient sites were assessed on drilling by the surgeon's tactile sense and recorded as D1-D4 based on Misch criteria. Linear regression analysis was used to evaluate the relationship between density values of implant sites.

RESULTS

The mean bone density was 536.94 ± 220.39 HU. There were 7.7% implants in bone type D1, 46.2% in D2, 32.7% in D3, and 13.5% in D4. Bone classification according to Lekholm and Zarb was significantly correlated to the surgeon's tactile sense (Spearman's rho = 0.36; P = 0.01) and with HU on CT images (Spearman's rho = -0.61; P < 0.001). The surgeon's tactile sense had a significant correlation with bone density in preoperative CT scans (Spearman's rho = -0.67; P < 0.001). A significant correlation was found between the bone density in HU with age (Spearman's rho = 0.34; P = 0.01).

CONCLUSION

A high-quality cross-sectional CT may suffice as a site-specific preoperative diagnostic predictor that can confirm and complement the tactile sense of the surgeon to help differentiate good, moderate, and poor bone density.

Evaluation of Effective Transmission of Light Through Alveolar Bone: A Preliminary Study

Introduction: The aim of the present study was to determine the effective transmission of 660 and 780 nm lasers through mandibular and maxillary alveolar bones in the buccal-lingual/ palatal direction. Methods: The laser probe was positioned in direct contact with the surface of the anterior, middle and posterior regions of each bone (5 dried maxillae and 5 mandibles) and the power meter was positioned on the bone wall opposite to the radiated wall for the measure of the remaining energy passing through the bone tissue. Ten measurements were performed with each laser at each irradiated point. Results: Transmitted power was significantly higher in bones irradiated with 780 nm laser. Tendencies toward greater average power transmitted in the anterior region of both bones at both wavelengths were also observed. Conclusion: Dosimetry and the choice of light source may be adjusted according to the anatomic region of the alveolar bone to be treated.