D3 Bone Research Articles

Reliability of Grayscale Value for Bone Density Determination in Oral Rehabilitation using Dental Implants.

Quality and quantity of jaw bones have been previously classified in literature using different methods. Imaging modalities such as computed tomography (CT), successfully determine bone density of jaws. This study aims to establish the role of cone-beam CT (CBCT) in determining the density of cortical and cancellous bones at different jaw sites. Eighty-three possible implant sites in healthy patients were evaluated using NewTomGiano CBCT machine. Cross-sections were obtained and cortical and cancellous bone densities on different aspects of the virtual implant in terms of Hounsfield unit (HU) were determined using New Net Technologies software version 6.1 and were classified according to software from D1 to D4. Data were entered into SPSS software (version 19.0) and were statistically analyzed. The mean HU showed the highest value for cortical and cancellous in the anterior mandible (mean HU 1874.01 and 1131.73, respectively) followed by the posterior mandible (mean HU 1789.20 and 872.95, respectively) and least in posterior maxilla (mean HU 1068.26 and 830.04, respectively). Maximum D1 bone type was found in cortical bone and D2 bone type was noted in cancellous bone area. Males showed very highly significant cortical bone thickness (P < 0.001) whereas females showed more cancellous bone thickness but the results were nonsignificant. A high degree of concordance between different regions of jaw bones with a strong correlation between the four bone types was obtained. Bone density plays a pivotal role in determining the prognosis of the implant. CBCT has proven to be beneficial in bone density analysis.

Investigating the effect of insertion torque on marginal bone loss around dental implants

Background/PurposeThe use of dental implants in restoring function, esthetics, speech, and health of oral tissues has been growing in recent years. Evaluating marginal bone resorption and the survival rate of implants placed with different torques values is crucial. The primary aim of the present study was to evaluate the effect of different insertion torque values on marginal bone loss around dental implants placed in the posterior region of the mandible. Materials and methods37 patients were involved in this study. Patient data (age, gender), implant characteristics (length, diameter), insertion torque values, gingival biotype, and bone quality were recorded, and parallel periapical radiographs measured marginal bone loss. The relationship between variables was obtained using independent t-tests, Pearson correlations, and regressions. ResultsThe present study found a positive and significant correlation between implant insertion torque and marginal bone loss (MBL)around the dental implants during the first year after placement. Furthermore, patients with D2 bone density at the implant placement site and thin gingival biotype also had significantly higher MBLs from baseline until crown delivery and first-year follow-up than those with D3 bone density and thick gingival biotypes, respectively. ConclusionA lower torque is necessary for high-risk patients to increase implantation success due to identifying patients with an increased risk for MBL.

Primary Stability Assessment of Conical Implants in Under-Prepared Sites: An In Vitro Study in Low-Density Polyurethane Foams

Bone characteristics, the implant macrogeometry, and the drilling technique are considered the main important factors to obtain a good implant primary stability (PS). Indeed, although it is known that implant placement in poor bone sites increases the possibility of implant failure, several surgical procedures have been proposed to improve PS, such as site under-preparation. Hence, this in vitro study aimed to evaluate the insertion torque (IT), removal torque (RT), and resonance frequency analysis (RFA) of conical implants (3.3 and 4 × 13 mm) placed in under-prepared sites on 10 and 20 pounds per cubic foot (PCF) density polyurethane sheets (simulating a D3 and D2 bone, respectively) with and without a cortical sheet of 30 PCF in density (corresponding to a D1 bone). After using ANOVA or Kolmogorov–Smirnov test to elaborate data, the resulting IT and RT values were directly proportional to the polyurethane block densities (e.g., the lowest and highest IT values were 8.36 ± 0.52 Ncm in the 10 PCF density sheet and 46.21 ± 0.79 Ncm in the 20 PCF density sheet + cortical for 4 × 13 mm implants) and increased with the increasing amount of site under-preparation (the highest results for both implants were found with a 2.2 mm under-preparation, showing a significantly higher IT with a p &lt; 0.05 compared with others, especially in the highest-density sheets). Both implants inserted in the 20 PCF density block + cortical with all under-preparation protocols exhibited significantly higher RFA values (p &lt; 0.05–0.0001) compared with the corresponding ones in the 10 PCF block. Moreover, 3.3 × 13 mm implants showed the same results comparing the 20 PCF block and the 10 PCF block + cortical. In conclusion, in this in vitro study using low-density polyurethane blocks, the under-preparation of the implant insertion sites was shown to be effective in increasing implants’ PS.

Effect of crown stiffness and prosthetic screw absence on the stress distribution in implant-supported restoration: A 3D finite element analysis.

This in-silico investigation evaluated the mechanical impact of Morse tape implant-abutment interface and retention system (with and without screw) and restorative materials (composite block and monolithic zirconia) by means of a three-dimensional finite element analysis (3D-FEA). Four 3D models were designed for the lower first molar. A dental implant (4.5 × 10 mm B&B Dental Implant Company) was digitized (micro CT) and exported to computer-aided design (CAD) software. Non-uniform rational B-spline surfaces were reconstructed, generating a 3D volumetric model. Four different models were generated with the same Morse-type connection, but with a different locking system (with and without active screw) and a different crown material made of composite block and zirconia. The D2 bone type, which contains cortical and trabecular tissues, was designed using data from the database. The implants were juxtaposed inside the model after Boolean subtraction. Implant placement depth was simulated for the implant model precisely at crestal bone level. Each acquired model was then imported into the finite element analysis (FEA) software as STEP files. The Von Mises equivalent strains were calculated for the peri-implant bone and the Von Mises stress for the prosthetic structures. The highest strain values in bone tissue occurred in the peri-implant bone interface and were comparable in the four implant models (8.2918e-004-8.6622e-004 mm/mm). The stress peak in the zirconia crown (64.4 MPa) was higher than in the composite crown (52.2 MPa) regardless of the presence of the prosthetic screw. The abutment showed the lowest stress peaks (99.71-92.28 MPa) when the screw was present (126.63-114.25 MPa). Based on this linear analysis, it is suggested that the absence of prosthetic screw increases the stress inside the abutment and implant, without effect on the crown and around the bone tissue. Stiffer crowns concentrate more stress on its structure, reducing the amount of stress on the abutment.

Assessment of Osteoporosis and Vitamin D3 Deficiency in Patients with Idiopathic Benign Paroxysmal Positional Vertigo (BPPV).

Background and objectives: Osteoporosis and vitamin D3 deficiency may be risk factors of benign paroxysmal positional vertigo (BPPV). The aim of this study was to assess the prevalence of osteoporosis and 25(OH) vitamin D3 deficiency in a group of patients with idiopathic benign paroxysmal positional vertigo. Materials and Methods: Thirty-five patients (twenty-eight women and seven men) with posterior semicircular canal BPPV were enrolled in the study. The subjects underwent hearing assessment (tonal audiometry and impedance audiometry) and the Dix-Hallpike maneuver. Serum 25(OH) vitamin D3 levels were determined and lumbar spine bone densitometry was performed. The relationships between sex, age, height, Body Mass Index (BMI), vitamin D3 levels and bone densitometry results were assessed. Results: The diagnosis of osteoporosis was confirmed in 1 patient (3%), 3 subjects were osteopenic (8.6%), and normal bone densitometry was found in 31 (88.6%) patients. Conclusions: We found no statistically significant relationships between age, BMI or vitamin D3 levels and bone densitometry results in patients with idiopathic BPPV.

Deviation of Dental Implants Placed by Guided Implant Surgery in Bone Structures with Different Densities.

Purpose: This study aimed to evaluate the deviations of implants with two different geometries placed with a bone-supported stereolithographic surgical template into the bone of Misch classification densities of D2, D3, and D4. Materials and Methods: Eight maxilla and eight mandible models were macrodesigned according to the jaw geometries. Bone densities of these models were created in parallel with the most frequently observed densities in the locations: D3 bone density in the anterior maxilla, D4 bone density in the posterior maxilla, D2 bone density in the anterior mandible, and D3 bone density in the posterior mandible. A bone-supported stereolithographic surgical template was prepared in accordance with the jaw models and planning and used to place 64 NobelParallel Conical Connection RP 4.3 × 13 mm and 64 NobelActive 4.3 × 13 mm implants on the models. Global deviation, lateral deviation, angular deviation, and depth deviation between planned and placed implants were calculated with Hypermesh. The Kruskal-Wallis test was used to analyze the differences between deviation data of the study groups, and the Mann-Whitney U test was used for pairwise comparisons of groups with significant differences. Significance was evaluated as P < .05. Results: The study groups showed statistical differences in terms of global, lateral, and depth deviation (P = .017, P = .044, and P = .012, respectively); no statistical difference was detected in terms of angular deviation (P > .05). When the data of all studies were evaluated, the deviation values for all maxillary and mandibular implants were examined regardless of bone and implant type; no statistical difference was found between the arches in terms of deviation type (P > .05). Conclusion: Regardless of the macrogeometry of the dental implants placed with the guide, no significant difference was observed between the deviation values of the different bone densities they were applied to.

An in vitro study evaluating the efficacy of a novel mount with torque control designed to tighten Osstell® transducers.

To evaluate the efficacy of a novel mount with torque control for tightening of Osstell® transducers and to determine the reliability of recorded ISQ measurements from implants placed in various bone densities. MATERIALAND METHODS: Fifty-six implants, comprising seven different implant types, were placed in eightpolyurethane blocks representing D1, D2, D3, and D4 bone densities. Resonance frequency analysis (RFA) transducers were attached to each implant in four different ways: (a) hand tightening, (b) hand tightening with a SmartPeg Mount™, (c) hand tightening using the novel mount with torque control (SafeMount) and (d) tightening to 6 Ncm with a calibrated torque device. ISQ measurements were taken and a second operator repeated the measurements. Intraclass correlation coefficient (ICC) was calculated to assess the reliability of the measurements and linear mixed effects regression was employed to determine the effect explanatory variables had on ISQ values. There was a statistically significant difference in ISQ values obtained by hand tightening transducers compared to the calibrated torque device p < .001, 95%(-2.89, -1.21) but not between any other tightening methods. There was excellent agreement between the two RFA devices (ICC 0.986) and between buccal and mesial measurements (ICC 0.977). For all transducer tightening methods there was excellent inter-operator agreement in D1 and D2 (ICC > 0.8) but very poor agreement in D4 (ICC < 0.24). Bone density accounted for 36% of the variation in ISQ values, the implant for 11% and the operator for 6%. SafeMount, did not significantly improve the reliability of the RFA measurements when compared to the standard mount, but calibrated torque devices seem to have benefits when compared to tightening the transducers by hand. Results also indicate that the ISQ values should be interpreted with caution when measuring implant stability in poor quality bone regardless of the implant geometry.

Effects of bone type and occlusal loading pattern on bone remodeling in implant-supported single crown: A finite element study.

To assess the influence of bone types and loading patterns on the remodeling process over 12 months according to the variations in stress, strain, strain energy density (SED), and density allocation in the bone of implant-supported single crown. A three-dimensional finite element of a single crown implant was modeled in five different bone types (D1-D4, and grafted bone). A 200N load was applied on an implant crown with three occlusal loading patterns (nonfunctional contact, functional contact at center, and at 2-mm offset loading). During the first 12 months after implant placement, the SED was employed as a mechanical stimulus to simulate cortical and cancellous bone remodeling. Functional contact at 2-mm offset loading led to a higher bone remodeling rate and stress compared to functional contact at center and nonfunctional contact. Under 2-mm offset loading, the greatest remodeling rate after 12 months was achieved with D3 and D4, D2, grafted, and D1 cortical bone with an average peri-implant density of 1.95, 1.77, 1.56, and 1.50g/cm3 , respectively. Meanwhile, the highest von Mises stresses were found in D4 (22.2MPa) and D3 (21.9MPa) bones. A greater stress concentration and remodeling rate were found when an off-axial load was applied on an implant placed in low bone density. Although the fastest remodeling processes resulting in increased bone density and strength were found in D3 and D4 bone types with greater off-axial loading that may provide greater bone engagement, it could increase stress concentrations that are susceptible to inducing implant failure.

Evaluation and Comparison of Stress in Divergent and Convergent Collar Designs of Implants With Different Bone Densities: A Finite Element Study.

The failure and the success rate of an implant depends on biomechanical factors, esthetics and painless sterile implant surgery conditions, out of which stresses applied to the bone and its surrounding, bone-implant interface, material characteristics of the implant used and the strength of the bone and its surrounding are the important factors. This study aimed to evaluate the stress distribution of divergent collar design (DCD)and convergent collar design (CCD) implants placing them in four different densities of the bone (D1, D2, D3 and D4).The evaluation of the stress distribution of DCDand CCD was performed using the 3D finite element method (FEM), by placing them in four different bone densities.In addition to this, a comparison of the effect of DCD and CCD in terms of stressdistribution in the bone was also done. The softwareused to process the geometric characteristics of the missing first molar in the mandibular section were Ansys, version 19.2, CATIA, version 5, and Solidworks (Dassault Systèmes). Using these software, three models were designed and successfully restored using an all-ceramic crown implant. The first model was a geometric modelof the first molar mandibular bone section, the second model was a cylindrical implant (4x10mm) with a DCD and CCD, and the third model had titanium alloy (Ti-6Al-4V) properties incorporated into the implant. The D1 bone model showed the lowest stress concentration compared to D2, D3, D4. The DCD showed the lower stress and strain concentrations as compared to the CCD in the contiguous crestal bone in all the densities of the bone in both vertical and lateral or oblique loadings. The DCD with the D1 bone showed the least stress concentration around the crestal bone region. The results of this study also showed that the maximum von Mises stress was observed in the crestal region or the neck of the implant for both the convergent and divergent collar implant designs in all the four densities of the bone. Before a patient trial of a new implant design or a new implant material, finite element analysis (FEA) gives us a clear picture of what will be the patient bone response when an implant will be placed and loaded. FEA also gives us an opportunity to test a new implant material without putting a patient at risk. In this study, four different types of bone were incorporated with two different implant collar designs. Each implant assembly was subjected to vertical as well as oblique forces. The response of each bone type for the titanium alloy implant was recorded. A color-coded response for the magnitude and the location of the maximum stress received by the bone was observed.Maximum stresses were seen in the crestal region. As this is a computer-based model, dynamic loading was not possible. This study provided us with the possible outcome in patients under a static load. Further studies can be conducted invivo to record dynamic loading responses as well as long-time loading responses.

Validation of the Implant Stability Test for Implant Provisional Crowns: An In Vitro Study

Implant treatment has evolved and is now performed using various techniques. However, the osseointegration duration required for poor primary stability or immediate loading is unclear and depends largely on the surgeon’s experience. We sought to verify whether implant stability can be quantified after immediate loading, using AnyCheck®. Six implants were placed in simulated bone blocks classified by bone quality as D1–D4 and further divided into healing abutment and provisional crown groups. The implant stability test (IST) values of both groups were measured using AnyCheck®. All bone qualities from D1 to D4 differed significantly between the provisional crown and healing abutment groups (p &lt; 0.001). In both groups, the IST values were the highest for D1 bone and lowest for D4 bone. There were significant differences in bone quality between the provisional crown and healing abutment groups. The correlations between the groups differed based on bone quality. However, the IST values of both groups differed by a minimum of 4 and maximum of 7. These results suggest that AnyCheck® is useful for quantifying the implant stability after immediate loading. Using an index to quantify the implant and bone stability for immediate loading may shorten treatment duration and increase success rates.

Factors Influencing the Accuracy of Guided Surgery: An In Vitro Trial.

Purpose: To examine how the accuracy (linear and angular deviation) of implants placed using computer-guided surgery varies in relation to the type of surgical technique (fully guided, half-guided, vs freehand implant placement), bone density (type D1 to D4 bone), and type of support surface (tooth- vs mucosa-supported). Materials and Methods: A total of 32 mandible models were produced (16 partially edentulous and 16 edentulous) using acrylic resin, each calibrated to a different bone density (D1 to D4). Four implants planned using Mguide software were placed in each acrylic resin mandible. A total of 128 implants were placed, distributed according to bone density (D1 to D4, n = 32), the degree of intervention in the surgery (fully guided [FG] = 80, half-guided [HG] = 32, and freehand surgery [F] = 16), and the type of support surface (tooth-supported: n = 64 and mucosa-supported: n = 64). To determine the linear, vertical, and angular deviations between the planned three-dimensional position and the actual position of the implants, the linear and angular difference between them was calculated, with the analysis performed through preoperative and postoperative CBCT scans. The effect was analyzed using parametric tests and linear regression models. Results: All parameters of linear and angular discrepancy in the various regions analyzed (neck, body, and apex) were primarily influenced by the technique and, to a lesser extent, by the bone type, although both variables were predictive and highly significant. These discrepancies tend to increase in completely edentulous models. The regression models show that linear deviations increase by between 630.2 μm at neck level in the buccolingual direction and 836.7 μm at apex level in the mesiodistal direction when comparing the FG and HG techniques. This increase is accumulative when comparing the HG and F techniques. Regarding the effect of bone density, the regression models found that linear discrepancies increase by between 132.6 μm in the axial direction and 199.0 μm at the apex of the implant in the buccolingual direction with each reduction in bone density (D1 to D4). Conclusion: According to this in vitro study, the highest implant placement predictability is found among dentate models with high bone density and a fully guided surgical technique.

In-vitro investigation of primary stability of orthodontic mini implants with different lengths using resonance frequency analysis

Out of various ways of gaining anchorage, mini implants are gaining attention due to its minimum compliance and maximum curative effects.Mini implants are considered successful if they have sufficient primary stability that comes from mechanical interlocking of mini implant with the bone.Factors which influence the implant stability are bone physiology, implant size, shape and surface characteristics. Considering all other factors within anatomic constraints, what may play a role in primary stability of mini implants is length. Literature search to correlate mini implant length with primary stability was found to be insufficient and hence this study was undertaken. In this study, two goat jaws were subjected to spiral 3D CT scan and the areas with D2 bone density were identified and marked. In these D2 density marked areas, 30 implants of 1.5 x 6mm (GROUP A) and 30 implants of 1.5 x8mm (GROUP B) were placed. Their stability was measured by Radio Frequency Analysis using Osstell ISQ device with its Smart Peg. A connector was fabricated to make the fit of smart peg compatible with the head of mini implant. Readings were made in 5 different directions for each implant and their average value was considered as final reading. It was noted that primary mini implant stability is significantly higher (p 0.034) with GROUP B implants than with GROUP A implants. The increased length of mini-implants positively affects its primary stability and should be taken into consideration when implants are used as anchorage devices.

Analysis of bone stress and primary stability of a dental implant using strain and torque measurements

IntroductionThe consensus among researchers is that early failure of dental implants is due to the lack of primary stability and compressive stress on the peri-implant bone that exceeds the physiological tolerance. ObjectiveThe objective of this work is to propose a new methodology to quantify bone stress during dental implant insertion and to correlate it with primary stability. Materials and MethodsTitanium dental implants with a diameter of 3.75 mm were inserted in a 3.35 mm hole of a synthetic bone of polyurethane (PU) foam with a density of 20 PCF (0.32 g/cm3). During insertion, the insertion torque was measured with a digital torque meter and the bone strain was measured with strain gages located at 2, 4, 6, 8, and 10 mm from the coronal region. ResultsThe tests showed that the compressive strain is maximum in the third coronal region and decreases in the apical direction. The data also showed that there is a relationship between strain, insertion torque, and the primary stability of dental implants. ConclusionThe stress and strain on the bone progressively decreased from the coronal to the apical third. The maximum compressive stress (0.42 MPa) during insertion of the implant did not exceed bone strength. Insertion of 3.75 mm implants in type D2 bone with a 3.35 mm hole provides adequate primary stability without excessive compression of the bone. Clinical SignificanceFor the implant-bone combination used in the present study, the compressive stress generated during implant insertion did not exceed the physiological limit of cortical and medullary bone to the point of impairing osseointegration.

Effect of orthodontic retraction force on thick and thin gingival biotypes in different grades of gingival recession and alveolar bone quality: A finite element analysis.

To evaluate the effect of orthodontic retraction force on thick and thin gingival biotypes of anterior teeth having grade I and II gingival recession with D1 and D2 alveolar bone densities by assessing the displacement of teeth and deformation in gingival tissue, along with evaluating the amount of equivalent stress on teeth and gingiva in finite element model. Based on cone-beam computed tomography datasets, eight models (LC01-LC08) of maxilla with appliance assembly were created. A retraction load of 150 gm was applied on each model during the finite element analysis (FEA), and then values of teeth displacement, gingival deformation, and von Mises stress were evaluated. All the models with D1 bone density (LC01-04) were showing gingival deformation, whereas models with D2 bone quality (LC05-08) give no significant outcome. The amount of von Mises stress for teeth and gingival tissue in each model was the same for both central and lateral incisors. All the models having D1 bone quality showed greater gingival deformation after applying retraction force, whereas in models with D2 bone density, deformation was not significant. Changes in gingival tissue are brought about by orthodontic treatment, which also helps to correct the periodontal defects; however, bone density plays a significant role in improving gingival recession.

Efficacy of Three Different Photobiomodulation Therapies on Primary and Secondary Implant Stability in D3 and D4 Bone Type- A Research Protocol for Randomised Controlled Trial

Introduction: Osseointegration is considered one of the most important deciding factors to check for implant stability, which decides successful outcome of the implant. Photobiomodulation has been used to improve the implant stability by enhancing osseointegration. Photobiomodulation (PBM) or Low-level Laser Therapy (LLLT) causes an enhanced effect in the bone implant contact. Need for the Study: There are no definitive therapies/protocol of LLLT in cases of bone density of D3 and D4. Also There are no studies in literature which compares the different laser settings so that a standardised setting can be established. Therefore, there is need to generate evidence whether reducing the number of appointments and reducing the amount of energy given in D3 and D4(compromised) bone can help achieve early loading in patients. Aim: To evaluate and compare the effect of three different photobiomodulation therapies on primary and secondary implant stability in D3 and D4 bone type in comparison to control group to achieve early loading. Materials and Methods: This randomized controlled, double blinded study allocated 108 patients having D3 or D4 bone according to Misch classification into six groups. Three different PBM therapy which is either Therapy A, B or C(placebo) will be used. The implant stability will be measured by Ostell meter in Implant Stability Quotients (ISQ) scale, immediately after surgery, after 3 weeks, after 12 weeks and after 6 months of surgery. The bone density will be measured before surgery and 3 months after surgery. Expected Outcome: At the end of the study, an evidence will be generated whether reducing the number of appointments and reducing the amount of energy given in D3 and D4(compromised) bone can help achieve early loading in patients. Patients treated using PBM therapy either protocol A or protocol B may show enhanced implant stability.

Influence of implant design and length on stress distribution in immediately loaded implants in posterior maxilla - A two-dimensional finite element analysis.

The aim of this two dimensional (2D) finite element analysis study was to evaluate the influence of implant design (step and tapered) and length on stress distribution at bone implant interface, when placed in maxillary posterior bone under immediate loading protocol. 2D finite element models were developed to simulate the two types of implant designs, i.e., Tapered and step implants of 3.75-mm - Diameter and 6 and 10 mm lengths, respectively. Maxillary posterior bone quality (D4 bone) was simulated with a very thin cortical bone (0.5 mm) for the placement of implants. The respective material properties were assigned. The implant designs incorporated microthreads at the crestal part and rest of the implant body incorporated Acme threads. Forces of 100 Newtons were applied vertically and in oblique direction (at an angle of 45°) to long axis of the implants. Total deformation (micromovements), stresses and strains were evaluated at the bone implant interface. The results of micromovements, stresses and strains were found to be lower for long implants as compared to short implants. Also, all the values were found to be higher for oblique loads as compared to vertical loads. The von mises stress values were highest for 6 mm step implants and lowest for 10 mm step implants. In the presence of low bone density with optimal bone height, standard diameter long step implants can be used. Incorporation of microthreads at the crestal portion and acme threads for body portion of the implant presents a good option to be used under immediate loading protocol.

Influence of different drilling protocols and bone density on the insertion torque of dental implants.

The insertion torque of dental implants will depend on a combination of different factors such as bone density, the design of the implant and the drilling protocol used. However, it is not clear how the interaction of these factors affects the final insertion torque and which drilling protocol should be used in each clinical situation. The aim of this work is to analyse the influence of bone density, implant diameter and implant length on the insertion torque using different drilling protocols. An experimental study was carried out in which the maximum insertion torque was measured, in standardised polyurethane blocks (Sawbones Europe AB) of four densities, for M12 Oxtein dental implants (Oxtein, Spain) with diameters of 3.5, 4.0, 4.5 and 5mm, and lengths of 8.5mm, 11.5mm and 14.5mm. All these measurements were carried out following four drilling protocols, a standard protocol, adding a bone tap, cortical drill or conical drill. In this way, a total of 576 samples were obtained. For the statistical analysis, the table of confidence intervals, mean, standard deviation and covariance was carried out, in total and grouped by the parameters used. The insertion torque for D1 bone obtained very high levels, reaching 77 6.95 N/cm, these values improved with the use of conical drills. In D2bone, the mean torque obtained was 37.89±13.70N/cm, with values within the standard. In D3 and D4bone significantly low torques were obtained with values of 14.97±4.40N/cm and9.88±4.16N/cm (p>0.001) respectively. In D1 bone, conical drills must be incorporated in drilling to avoid excessive torque, while in D3 and D4 bone, these would be contraindicated, as they drastically decrease the insertion torque, which may compromise the treatment.

Correlation between Primary Stability of Dental Implants and Bone Density: A Retrospective Analysis.

Dental implants have gained popularity in recent years. The most important variable in determining the effectiveness of the implant's primary stability is bone density. The success of the implant depends on proper procedure and implant stability. With this background, the aim of the present study was to study the correlation between primary stability and bone density. The present retrospective study was conducted among 2,440 patients who had undergone implant treatment in the Department of Implantology, Saveetha Dental College and Hospitals, Chennai, from June 2021 to February 2022. Data regarding patient's age, gender, implant location, bone density, and primary stability were taken into consideration. Association between primary stability and bone density was assessed using the Chi-square test. Of the subjects, 33.42% had D2 bone density in the lower posterior region; 13.98% had D3 density in the lower posterior region. Primary stability of 30-40 Ncm was seen in the majority of the subjects; 32.64% who had primary stability of 30-40 Ncm had D2 bone density. There was a statistically significant association between implant site and bone density (p = 0.04) and primary stability and bone density (p = 0.03). Within the limitations of the study, it can be concluded that there is a strong association between implant primary stability and bone density.

Dental biomechanics of root-analog implants in different bone types

Statement of problemWhen implants are applied to restore oral function, the masticatory load on the crown will lead to stress development in all parts of the crown-abutment-implant-bone system. An optimal design of the whole system will be important for sustained function. PurposeThe purpose of this 3-dimensional (3D) finite element analysis (FEA) study was to evaluate the influence of the root-analog implant (RAI) design in molar rehabilitation and bone type. Material and methodsTwelve 3D models of single posterior implant-supported restorations were created according to the zirconia implant design (monotype, 2-piece, or RAI) and bone type (D1, D2, D3, and D4, according to the Misch classification). The models were composed of cortical bone, cancellous bone, implant, cement layers, and a monolithic ceramic crown. For the 2-piece zirconia implant model, the titanium base, prosthetic screw, and framework were also designed. All materials were assumed to behave elastically throughout the entire analysis. The bone was fixed, and an axial loading of 600 N was applied to the contacts on the occlusal surface of the crowns. Results for the crown and implant were obtained in maximum principal stress, as well as the von Mises stress for the model and bone microstrain. ResultsHigh stress concentration was observed at the intaglio surface of the crowns near the loading region. Regardless of the design, the stress trend in the implant was similar, increasing proportionally to the bone type (D1>D2>D3>D4). RAI showed a homogeneous stress field near the values calculated for the conventional designs, but with lower magnitudes. The 2-piece zirconia model showed the highest stress magnitude regardless of the bone type and, therefore, the highest failure risk. All models showed a higher strain in the cortical bone than in the cancellous bone, located predominantly in the cervical region. A strain analysis showed that both conventional implant models presented similar behavior for D1 and D2 bone types, with an increasing difference for D3 and D4. RAI showed the lowest strain regardless of the bone type. ConclusionsRoot-analog zirconia implants present a promising biomechanical behavior for dissipating the masticatory load in comparison with conventional screw-shaped implants.

Comparative Evaluation of Osseodensification Versus Conventional Osteotomy Technique on Dental Implant Primary Stability: An Ex Vivo Study.

Purpose One of the commonest treatment options for replacing missing teeth is a root-form implant. Clinically, the key mechanical factor in achieving success is primary stability. This ex vivo study aims to evaluate whether osseodensification method will achieve good primary stability or the conventional drilling protocol. Methods Fresh iliac bone of the sheep was selected similar to D3 and D4 bone densities. A total of 22 osteotomy sites were prepared in the bone sample, of which 11 were prepared by osseodensification method (test group) and other 11 by conventional undersized drilling (control group). Primary stability was measured using insertion torque (IT), resonance frequency analysis (RFA), and reverse torque values (RTVs) by measuring implant stability quotient (ISQ). The recorded data were statistically analyzed using Statistical Package for the Social Sciences (SPSS) Version 22.0. The differences between groups were compared using the Mann-Whitney U test and independent t-test. The Pearson correlation coefficient test was performed to measure the linear relationship between two variables. The statistical significance level was established at p<0.05. Results When the correlation among IT, RTV, and ISQ was measured, a statistically significant correlation between IT and RTV (p=0.001) and between IT and ISQ (p=0.0001) was observed. A statistically significant (p=0.014) correlation between RTV and ISQ was also found. Conclusion Osteotomy prepared by osseodensification method showed higher IT, RTV, and ISQ values than the conventional undersized group.