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

Histological evaluation of osseointegration between conventional and novel bone-level tapered implants in healed bone-A preclinical study

AIMS

To histologically compare osseointegration and crestal bone healing between newly introduced tapered, self-cutting bone-level test implants and tapered bone-level control implants in sites with fully healed sites.

METHODS

Sixty-six implants (33 test, 33 control) were placed 1 mm subcrestally in a minipig model and underwent qualitative histologic and quantitative histometric analyses after 3, 6 and 12 weeks of submerged healing. The primary and secondary outcomes were the bone-to-implant contact (BIC) and first bone-to-implant contact (fBIC). Outcomes between the test and control implants were statistically compared.

RESULTS

The BIC values of the test implants were comparable and non-inferior over the time points studied, except for the 12 weeks time point which showed statistically significantly higher BIC values of the test (88.07 ± 5.35%) compared to the control implants (80.88 ± 7.51%) (p = .010). Similarly comparable and non-inferior were the fBIC values, except for the 6-week outcome, which showed statistically higher values for the test (-546.5 ± 450.80 μm) compared to the control implants (-75.7 ± 100.59 μm). fBIC results for the test implants were qualitatively more stable and consistent between test time points.

CONCLUSION

Novel self-cutting bone-level test implants demonstrated superior osseointegration and similar bone levels compared to conventional bone-level implants after a healing period of 12 weeks in healed ridges.

A comparative study on bone density before and after implant placement using osseodensification technique: a clinical evaluation

BACKGROUND

Dental implant success critically depends on the primary stability of the implant, which is significantly influenced by the bone density at the osteotomy site. Traditional drilling techniques for osteotomy preparation often compromise bone volume and quality. This study aimed to evaluate the impact of osseodensification, a novel osteotomy preparation technique, on bone density and implant stability. The technique utilizes specialized drills that operate in a counter-clockwise direction to compact autografted bone laterally and apically, preserving and enhancing bone density.

METHODS

A total of 32 patients undergoing dental implant surgery were included in this study. Pre-operative and post-operative bone densities at the apical, mesial, and distal regions of the osteotomy sites were measured using Dentascan (CT) and analyzed with Radiant DICOM software. The study utilized osseodensification drills for osteotomy preparation, comparing pre-operative and post-operative bone densities to assess the technique's efficacy.

RESULTS

The study found a statistically significant increase in bone density post-operatively (p < 0.001), with the greatest improvement observed in the distal region, followed by the mesial and apical regions. The findings underscore osseodensification's effectiveness in enhancing bone density and primary stability, with the distal region exhibiting the highest bone density.

CONCLUSION

Osseodensification represents a significant advancement in implant dentistry for osteotomy preparation. By preserving and increasing bone density through compact autografting, this technique not only improves primary stability but also offers potential benefits in indirect sinus lifting and alveolar ridge expansion. The study advocates for the broader adoption of osseodensification drills in clinical practice to achieve better outcomes in dental implantology.

TRIAL REGISTRATION

This study received ethical approval from The Research Ethics Committee at King Khalid University's under Approval no. ECM#2024 - 216. Additionally, it was registered with ClinicalTrials.gov, identifier no: NCT06268639.

The Interrelation between Cortical Bone Thickness and Primary and Secondary Dental Implant Stability: a Systematic Review

Objectives

Dental implants have emerged as a reliable and long-lasting solution for missing teeth, offering advantages over traditional prosthetic options. The aim of this systematic review was to thoroughly explore the correlation between cortical bone thickness of the jaws and bone-level dental implant primary and secondary stability.

Material and Methods

A comprehensive literature search was conducted in MEDLINE (PubMed), ClinicalKey and the Cochrane Library from 1 January, 2019 to 21 June, 2024. This review focused on patients undergoing dental implant placement with varying cortical bone thicknesses and implant stability levels. Quality and risk-of-bias assessment evaluated by Cochrane risk of bias tool.

Results

Out of 160 screened articles, 28 were reviewed in full, and 6 met the inclusion criteria, involving 209 patients and 418 implants. Implant stability quotient (ISQ) values showed no significant correlations during baseline and secondary assessments (P > 0.05). Correlations were noted between implant stability, bone density, alveolar ridge width, and implant size (P < 0.01). ISQ and insertion torque value (ITV) were strongly correlated at insertion (P < 0.001) but not at follow-ups (P = 0.059 at 2 months, P = 0.817 at 6 months, P = 0.029 at 12 months). ISQ values increased over time (P < 0.001). Implants in native bone showed higher ISQ values at baseline (P = 0.011), 8 weeks (P = 0.013), and 12 weeks (P < 0.001). Regions with thicker cortical bone demonstrated superior primary stability.

Conclusions

Thicker cortical bone enhances primary implant stability, as indicated by higher insertion torque and implant stability quotient values.

Comparative osseointegration of hydrophobic tissue-level tapered implants-A preclinical in vivo study

PURPOSE

To histometrically compare the osseointegration and crestal bone healing of a novel tapered, self-cutting tissue-level test implant with a standard tissue-level control implant in a submerged healing regimen.

MATERIALS AND METHODS

In a mandibular minipig model, implants were inserted and evaluated histometrically after a healing period of 3, 6, and 12 weeks. The primary outcome was the evaluation of bone-to-implant contact (BIC) and secondary outcomes were primary stability as per insertion torque and first BIC (fBIC). Outcomes for the test and control implants were compared using Wilcoxon signed-rank tests and mixed linear regression models.

RESULTS

Insertion torque values were significantly higher for the test (50.0 ± 26.4 Ncm) compared to the control implants (35.2 ± 19.7 Ncm, p = .0071). BIC values of test implants were non-inferior to those of control implants over the investigated study period. After 12 weeks, the corresponding values measured were 81.62 ± 11.12% and 90.41 ± 4.81% (p = .1763) for test and control implants, respectively. Similarly, no statistical difference was found for fBIC values, except for the 12 weeks outcome that showed statistically lower values for the test (-675.58 ± 590.88 μm) compared to control implants (-182.75 ± 197.40 μm, p = .0068).

CONCLUSIONS

Novel self-cutting tissue-level implants demonstrated noninferior osseointegration and crestal bone height maintenance to the tissue-level implants. Histometric outcomes between both implants demonstrated test implants were statistically noninferior to control implants, despite substantial differences in the bone engagement mechanism and resulting differences in insertion torque and qualitative bone healing patterns.

Influence of titanium and titanium-zirconium alloy as implant materials on implant stability of maxillary implant retained overdenture: a randomized clinical trial

BACKGROUND

Long-term success of implant restoration depends on many factors one of them is the sufficient implant stability which is lowered in compromised bone density sites such as the maxilla as it is categorized as type III & IV bone, so searching for a new innovation and updates in implant material and features is very mandatory. So, the aim of this study was to compare between two implant materials (roxolid and traditional titanium) on the primary and secondary stability of implant retained maxillary overdenture.

METHODS

Eighteen completely edentulous patients were selected. All patients received maxillary implant-retained overdentures and lower complete dentures; patients were divided equally into two groups according to the type of implant materials. Group A received a total number of 36 implants made of roxolid material and Group B received a total number of 36 implants made of traditional titanium alloys. Implant stability was assessed using ostell device, the primary implant stability was measured at the day of implant installation however, secondary implant stability was measured after six weeks of implant placement. Paired t-test was used to compare between primary and secondary stability in the same group and an independent t-test was used to compare between the two groups with a significant level < 0.05.

RESULTS

Independent t-test revealed a significant difference between the two groups with p -value = 0.0141 regarding primary stability and p-value < 0.001 regarding secondary stability, as roxolid implant group was statistically higher stability than titanium group in both. Paired t- test showed a statistically significant difference in roxolid implant group with p-value = 0.0122 however, there was non-statistically significant difference in titanium group with p-value = 0.636. Mann Whitney test showed a significant difference between the two groups regarding amount of change in stability with p value = 0.191. roxolid implant group showed a higher amount of change in stability than the titanium implant group.

CONCLUSION

Within the limitation of this study, it could be concluded that: Roxolid implants showed promising results regarding primary and secondary stability compared to conventional Titanium implants and can be a better alternative in implant retained maxillary overdentures.

TRIAL REGISTRATION

Retrospectively NCT06334770 at 26-3-2024.

Toward Digital Twin Development for Implant Placement Planning Using a Parametric Reduced-Order Model

Real-time stress distribution data for implants and cortical bones can aid in determining appropriate implant placement plans and improving the post-placement success rate. This study aims to achieve these goals via a parametric reduced-order model (ROM) method based on stress distribution data obtained using finite element analysis. For the first time, the finite element analysis cases for six design variables related to implant placement were determined simultaneously via the design of experiments and a sensitivity analysis. The differences between the minimum and maximum stresses obtained for the six design variables confirm that the order of their influence is: Young's modulus of the cancellous bone > implant thickness > front-rear angle > left-right angle > implant length. Subsequently, a one-dimensional (1-D) CAE solver was created using the ROM with the highest coefficient of determination and prognosis accuracy. The proposed 1-D CAE solver was loaded into the Ondemand3D program and used to implement a digital twin that can aid with dentists' decision making by combining various tooth image data to evaluate and visualize the adequacy of the placement plan in real time. Because the proposed ROM method does not rely entirely on the doctor's judgment, it ensures objectivity.

The application of CGF combined with GBR in alveolar bone increment for patients with anxiety disorder: A rare case report and literature review

RATIONALE

Selective serotonin reuptake inhibitors (SSRIs), one of the commonly used anti-anxiety drugs, may have impacts on bone metabolism and potentially lead to drug-induced osteoporosis. The traditional approach of oral implantation in individuals with both anxiety disorder and drug-induced osteoporosis poses a significant challenge. To address this issue, concentrated growth factor (CGF) has been utilized in patients undergoing concurrent alveolar ridge augmentation during oral implantation, resulting in favorable clinical outcomes. Consequently, combining CGF with guided bone regeneration (GBR) in alveolar bone increment may represent a promising new surgical approach for such patients. In this report, we present a case study of a 25-year-old male with anxiety disorder and drug-induced osteoporosis, in who CGF combined with GBR was employed in alveolar bone increment.

PATIENT CONCERNS

This article reports the case of a 25-year-old male who underwent cone beam computed tomography (CBCT) due to the absence of his right lower second molar for a period of six months. The CBCT scan revealed significant bone defects, which were attributed to the tooth loss and prolonged use of anti-anxiety drugs. Consequently, the patient sought medical assistance from our department.

DIAGNOSES

Based on the patient's self-report, he was diagnosed with an anxiety disorder. Additionally, the CBCT scan confirmed the loss of the right mandibular second molar and revealed the presence of dental irregularity and an alveolar bone defect.

INTERVENTIONS

During the patient's course of treatment with anti-anxiety medication, a combination of CGF and GBR was employed for the simultaneous implantation of the missing right mandibular second molar, along with bone augmentation.

OUTCOMES

The patient had a follow-up visit two weeks after the surgical procedure, and the wound in the operation area had healed satisfactorily. Six months later, CBCT images revealed excellent osseointegration. The buccal and lingual width of the alveolar bone measured 6.95mm, which was an increase of 1.35mm compared to the pre-implantation stage.

LESSONS

This article presents a case study in which CGF combined with GBR were utilized to address alveolar bone augmentation during the implantation phase in patients taking anti-anxiety medication. The results demonstrated that CGF combined with GBR, as a cutting-edge platelet concentrate technique, could effectively stimulate bone tissue proliferation in individuals who have been on long-term anti-anxiety medication, specifically in oral implant areas. This approach can help prevent poor osseointegration, promote higher osseointegration rates, and facilitate wound healing.

Influence of loading and grafting on hard- and soft-tissue healing at immediately placed implants: An experimental study in minipigs

AIM

To histologically evaluate the influence of (1) loading and (2) grafting on osseointegration and peri-implant soft-tissue healing at immediately placed, self-cutting progressive tissue-level implants (TLX) in a minipig model.

MATERIALS AND METHODS

TLX implants (n = 56) were immediately placed following the extraction of the mandibular first and second premolars, bilaterally, in a total of n = 14 minipigs. In each animal, the implant sites were allocated to the following four groups: (1) unloaded with simultaneous grafting using a bovine bone mineral; (2) unloaded without grafting; (3) loaded with simultaneous grafting; and (4) loaded without grafting. Histomorphometric assessments at 4 and 12 weeks (n = 7 animals each) included primary (i.e., bone-to-implant contact [BIC]) and secondary outcome measures (e.g., first BIC [fBIC], junctional epithelium length [JE], connective tissue contact length [CTC], biological width [BW = JE + CTC]).

RESULTS

At 4 weeks, mean BIC values ranged from 74.5 ± 11.6% in Group 2 to 83.8 ± 13.3% in Group 1, and, at 12 weeks, from 75.5% ± 7.9% in Group 2 to 79.9 ± 8.6% in Group 1. Multivariate linear mixed regression did not reveal any associations between BIC and implant loading or grafting at 4 and 12 weeks. At 12 weeks, significantly higher fBIC values were noted in Group 2 when compared with Group 1. All groups showed comparable JE, CTC, and BW values.

CONCLUSIONS

Implant loading and grafting had no major effects on osseointegration and peri-implant soft tissue healing at TLX implants.

Convergent angles of a tapered implant referred from the root profile of premolars

Background/purpose

Limited studies have discussed the convergent profiles regarding tapered implants based on biological considerations. This study analyzed the convergent angles (CAs) of premolar roots and imitated a tapered implant according to the anatomy of tooth roots.

Materials and methods

A total of 60 single-rooted premolars were explored by micro-computed tomography. Every individual root was divided into 10 segments corono-apically, and the roots' buccolingual (BL) and mesiodistal (MD) CAs were measured by sections. To mimic a dental implant, the irregular shape of examined root cross-sections was transformed into a circular shape with equal areas. A biomimetic dental implant (BDI) was reconstructed and its CAs were compared with those of the natural roots' BL and MD at the examined levels and overall estimation.

Results

In general, the maxillary and mandibular premolars demonstrated comparable CA patterns. However, significantly different CA patterns of BL, MD, and BDI were developed for both the maxillary and mandibular roots at the examined levels. The BL's CAs were greater than those CAs measured from the BDI and MD aspects, particularly for the sections at the middle and apical thirds of the roots. For overall CAs, the BDI's CAs were comparable with the average CAs of the BL and MD for both premolar groups.

Conclusion

Instead of a cylindrical configuration, the BDI prototype demonstrated a tapered model with a continuous slope. The average CA of BDI was 14°-24°, serving as a biological reference for future tapered implant design and research.

Esthetic and clinical outcomes after immediate placement and restoration: Comparison of two implant systems in the anterior maxilla-A cross-sectional study

AIM

To assess the esthetic and clinical performance of a novel self-tapping implant system for single-tooth restorations in the esthetic zone after immediate placement and provisionalization.

MATERIALS AND METHODS

This cross-sectional study included 52 patients contributing a total of 52 immediately placed and restored implants with ≥12 months after functional loading, comparing two different implant systems: Straumann® BLX (Institut Straumann AG, Basel, Switzerland; 25 patients) and Ankylos® (Dentsply Sirona, Hanau, Germany; 27 patients). As the primary outcome measure, peri-implant tissue esthetics were assessed by means of pink esthetics score (PES) rated by three independent clinicians. Moreover, as secondary outcome measures, the peri-implant tissue health was assessed by means of bleeding on probing, probing depth, and suppuration. Apart from that, the modified plaque index, keratinized mucosa width, and the presence of mucosal recessions were also assessed. When clinical signs suggested the possibility of peri-implantitis, radiographs were indicated to assess progressive bone loss.

RESULTS

The mean PES ratings were 12.10 ± 1.10 for Ankylos versus 11.2 ± 1.86 for BLX, both achieving good esthetic results without significant differences (p = 0.143). There were no differences among most clinical parameters (plaque, bleeding on probing, probing depth, peri-implant mucosal recession), although peri-implant mucositis was present in one-third of the cases. The inter-rater agreement on esthetics was not significant (p < 0.250).

CONCLUSION

Within the limitations of the present study, it was concluded that the use of either BLX or Ankylos implant systems was associated to comparable peri-implant health and good pink esthetic outcomes during immediate implantation and restoration protocols, for at least 12 months.

Biomechanical analysis of printable functionally graded material (FGM) dental implants for different bone densities

The long-term success of a dental implant is related to the material and design of the implant, and bone density. Conventional implants cause stress-shielding due to a mismatch between the implant and bone stiffness. Functionally graded porous materials and designs are a great choice for the design of implants to control the local stiffness at a certain location to meet the biomechanical requirements. The purpose of this study is to analyze five designs of axial and radial functionally graded materials (FGM) implants besides the conventional implant and conical and cylindrical shapes that were simulated with five different bone densities. The results showed that strain in bone increased with a decrease in cancellous bone density. The shape of the implant did not play an important role in strain/stress distribution. Conventional implants showed optimal strain (1000-2240 με) in low-density (0.7-0.8 g/cm3) bone, however, FGM implants produced optimal strain (990-1280 με) in the high-density bone (0.9-1 g/cm3) as compared to conventional implants. The proposed designs of FGM implants have the potential to address the complications of conventional implants in high-density bone.

Effect of enriched bone-marrow aspirates on the dimensional stability of cortico-cancellous iliac bone grafts in alveolar ridge augmentation

Background

The objective of the current study was to assess the clinical and radiological outcomes following autologous grafting from the iliac crest treated with autologous stem cells in-situ to reduce the postoperative bone graft resorption rate.

Materials and methods

The study group consisted of patients who underwent vertical augmentation of the jaws via bone grafts harvested from the iliac crest enriched with bone-marrow aspirate concentrates (stem cell group). The first control group (control) included 40 patients underwent a vertical augmentation with autologous bone grafts from the iliac crest. In the second control group, 40 patients received identical surgical procedure, whereas the autologous bone graft was covered with a thin layer of deproteinized bovine bone matrix and a collagen membrane (DBBM group). Clinical complications, implant survival, radiological assessment of the stability of the vertical height and histological evaluation at the recipient site have been followed up for 24 months postoperatively.

Results

No differences in terms of implant survival were observed in the groups. In the stem cell group, the resorption after 4–6 months was 1.2 ± 1.3 mm and significantly lower than the resorption of the control group with 1.9 ± 1.6 mm (P = 0.029) (DBBM group: 1.4 ± 1.2 mm). After 12 months, the resorption of the stem cell group was 2.1 ± 1.6 mm and significantly lower compared to the control group (4.2 ± 3.0 mm, P = 0.001) and DBBM group (resorption 2.7 ± 0.9 mm, P = 0.012). The resorption rate in the second year was lower compared to the first year and was measured as 2.7 ± 1.7 mm in the stem cell group (1-year bone loss in the time period of 12–24 months of 0.6 mm compared to 2.1 mm in the first 12 months). The resorption was significantly lower compared to the control group (4.7 ± 2.9 mm; P = 0.003, DBBM group: 3.1 ± 0.5 mm, P = 0.075).

Conclusions

Autologous bone-marrow aspirate concentrate could enhance the dimensional stability of the bone grafts and improve the clinical standard of complex reconstruction of the alveolar ridge. Even though the intraoperative cell enrichment requires an additional equipment and technical specification, it represents an alternative method for in-situ regeneration by osteogenic induction with a contribution of a manageable cost factor.

Influence of the Residual Ridge Widths and Implant Thread Designs on Implant Positioning Using Static Implant Guided Surgery

PURPOSE

Aggressive implant macrothread designs have been widely used. However, the effects of the aggressive thread design on the accuracy of static guided surgery, especially in a case of narrow residual ridge, have not been well-studied. The aim of this study was to evaluate the effects of two different implant macrothread designs and the residual ridge widths on the accuracy of tooth-supported static guided implant surgery.

MATERIALS AND METHODS

Forty implant fixtures with two different macrodesigns: a conventional thread design bone level tapered (BLT), and an aggressive thread design bone level tapered (BLX) were placed in 40 simulated polyurethane models with narrow and wide residual ridges. The placed implant positions were compared with the planned implant position and angulational deviation, as well as three-dimensional (3D) deviations at the entry and apex of the implant were measured. One-way ANOVA with Tukey's multiple comparisons (ɑ = 0.05) were used to determine level of significance between the mean and variance deviation values. 95% confidence intervals and box plots were used to demonstrate the means and ranges of precision.

RESULTS

In terms of angulational deviation, there was no statistically significant difference in the mean deviations for both types of implants, p = 1.55 and p = 0.84 for wide and narrow ridge groups, respectively. However, the range of deviation was much larger in the narrow ridge of the BLX group compared to the BLT group. In both narrow ridge and wide ridge, the BLX group had lower mean 3D deviation values at both the entry and the apex with statistically significant differences for both entry point of the wide ridge (p = 0.027) and narrow ridge (p = 0.022) as well as at the apex of the wide ridge (p = 0.006) but not the apex of the narrow ridge (p = 0.142).

CONCLUSION

The aggressive larger thread design of dental implants may influence the accuracy of implant placement more than the ridge dimension.