Radiological Outcomes of Bone-Level and Tissue-Level Dental Implants: Systematic Review

Effect of shape and design of the internal connection of tissue-level and bone-level implants on detorque values and removal forces: An in vitro study

STATEMENT OF PROBLEM

Optimal implant stability and preventing complications such as screw loosening are paramount concerns for implant-supported prostheses. However, studies examining the influence of various internal connection designs on detorque values and removal forces, critical aspects of implant success, are lacking.

PURPOSE

The purpose of this in vitro study was to assess the impact of the shape and design of the internal connection in tissue-level and bone-level implants on the detorque value and the force required for abutment removal from the implant.

MATERIAL AND METHODS

Forty dental implants were securely mounted in 10×6×20-mm acrylic resin blocks positioned perpendicular to the surface. The implants were divided into 4 groups (n=10): bone-level SM Torx, tissue-level PSI Torx, bone-level UF Hex, and tissue-level UF Hex implants. After exposure to a dynamic loading test at 31.2 N, 2 Hz and 106 cycles, measurements were made of both detorque values and removal forces. Statistical analyses, including 1-way ANOVA with a post hoc Tukey test and Kolmogorov-Smirnov test, were conducted to assess the results (α=.05).

RESULTS

The differences in detorque values among the 4 groups were statistically similar (P=.087). In terms of removal force values, tissue-level PSI implants exhibited the highest values, while bone-level UF implants had the lowest values, with significant differences in the removal forces among the 4 groups (P<.001). Pairwise comparisons revealed significant differences among the groups (P<.001), except for the comparison between tissue-level PSI and bone-level SM implants (P=.108).

CONCLUSIONS

While detorque values remain consistent across implant types, the shape and design of the internal connection of implants has a significant impact on the removal force required for abutment detachment from the implant.

Outcomes of treatment with short dental implants compared with standard-length implants: a retrospective clinical study

BACKGROUND

The size of dental implants is a key success factor for appropriate osseointegration. Using shorter implants allows the possibility of avoiding complex surgical procedures and reduces the morbidity of treatment. Shorter implants also enable implant-prosthetic rehabilitation after maxillofacial reconstructions where only limited bone is available. In this study, the success rates of short implants were examined and compared to those of standard-sized implants.

METHODS

Patients who received dental implants between 2007 and 2016 at the Department of Oro-Maxillofacial Surgery and Stomatology Semmelweis University were enrolled in the study. Several clinical parameters were recorded and supplemented with radiological examinations. The data were statistically analysed.

RESULTS

Thirty-four patients with a total of 60 implants were included. The average time after prosthetic loading was 39.33 ± 21.96 months in the group with 8-mm implants and 41.6 ± 27.5 months in the group with > 8-mm implants. No significant differences were observed between the two groups in terms of probing depth (short implants, 2.84 ± 0.09 mm; standard implants, 2.91 ± 0.35 mm) or mean marginal bone loss (short implants, 1.2 ± 1.21-mm mesially and 1.36 ± 1.47-mm distally; standard implants: 0.63 ± 0.80-mm mesially and 0.78 ± 0.70-mm distally).

CONCLUSIONS

In this study, the success rate of short dental implants was comparable to that of standard-sized implants. Consequently, it can be claimed that the long-term success of short dental implants does not differ significantly from the long-term success of standard implants.

Hydroxyapatite coatings versus osseointegration in dental implants: A systematic review

STATEMENT OF PROBLEM

Knowledge of the effectiveness of hydroxyapatite coatings on the surface of titanium dental implants is lacking because of difficulties in standardizing their thickness, roughness, and effect on osseointegration. The selection of articles describing this coating in osseointegration will be of great relevance to implant dentistry.

PURPOSE

This systematic review aimed to answer the question, "How effective is hydroxyapatite on titanium surfaces for osseointegration?"

MATERIAL AND METHODS

The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) 2020 guidelines were followed, and the protocol was registered on the international prospective register of systematic reviews (PROSPERO) database (CRD42023422601). The PubMed, Scopus, Web of Science, and Embase databases were searched, and articles were selected manually in 2 steps by 2 blinded investigators according to the previously selected eligibility criteria. The risk of bias was assessed using the systematic review center for laboratory animal experimentation (SYRCLE) tool.

RESULTS

Initially, 671 results were found. After analysis of eligibility criteria and full reading, 15 articles were included in the present review. Of these, 12 reported favorable osseointegration results for hydroxyapatite-coated surfaces, and 3 found no significant long-term difference between the coated and uncoated groups.

CONCLUSIONS

Hydroxyapatite surface treatment is effective in the osseointegration of titanium dental implants because it favors the absorption of proteins, adhesion, and proliferation of bone cells when obtained by methods that ensure proper adhesion. (J Prosthet Dent xxxx;xxx:xxx-xxx).

Dental implant failure rates with low insertion torque with a nonsubmerged surgical approach: A retrospective clinical study

BACKGROUND

It is currently unclear if a low insertion torque (IT) should prompt a clinician to submerge the dental implant at time of placement.

PURPOSE

This study aimed to analyze implant failure rates and marginal bone loss (MBL) as a function of IT and surgical approach.

MATERIALS AND METHODS

A total of 197 patients who had received 295 Mozo Grau (MG) implants were included in this study. The healing of submerged or nonsubmerged implants was evaluated in regular IT (≥20-25 Ncm) or low IT (<20-25 Ncm) cases. Implant failure and MBL were evaluated before prosthesis placement and at 6 and 12 months after functional loading with generalized estimating equations.

RESULTS

The overall 12-month implant failure rate was 4.8% (95% confidence interval [CI]: 2.7%-8.2%). When successful at 12 months, dental implants placed with low IT and nonsubmerging had the same MBL as implants dental implants placed with other approaches (mean difference = -0.02 mm; 95% CI -0.05 to 0.02). Low IT combined with nonsubmerging of the dental implant was associated with a 30-fold increased odds for dental implant failure (95% CI: 3.8-236.6).

CONCLUSION

low IT and nonsubmerged healing was associated with a high failure rate.

Marginal bone loss of tissue- or bone-level implants after simultaneous guided bone regeneration in the posterior mandibular region: A retrospective cohort study

PURPOSE

To analyze the marginal bone loss (ΔMBL) of tissue- or bone-level implants after placed with simultaneous guided bone regeneration (GBR).

MATERIALS AND METHODS

A total of 151 patients who received 104 tissue-level or 128 bone-level implants placement with simultaneous GBR in the mandibular posterior region between January 2011 and December 2016 were included in this study. The marginal bone level (MBL) was recorded using the radiographic data obtained at implant placement, second-stage surgery, and the follow-up visit. Generalized estimating equation (GEE) was used to compare the ΔMBL of tissue- and bone-level implants, and the influencing factors of ΔMBL were further analyzed.

RESULTS

At the last follow-up visit, the MBL of tissue-level implants was 0.73 ± 0.86 mm, above the rough-smooth interface, while that of bone-level implants was 0.82 ± 1.05 mm, above the implant platform. The ΔMBL of tissue-level implants was 1.03 mm, which was slightly higher than 0.81 mm of bone-level implants, but there was no significant difference (p > 0.05). No contributing factor associated with ΔMBL was identified by multivariate regression analysis in this study.

CONCLUSION

Within the limits of this retrospective analysis, the ΔMBL of tissue-level implants is similar to that of bone-level implants after placed with simultaneous GBR, and both types of implants can achieve desirable marginal bone stability.

Survival Rates and Clinical Outcomes of Implant Overdentures in Old and Medically Compromised Patients

Studies on the survival rate of implant overdentures in medically compromised patients are limited because most studies exclude patients with systemic diseases affecting implant prognosis. This retrospective study aimed to evaluate the survival rate and clinical outcomes of dental implants used for overdentures in medically compromised patients. A total of 20 patients (9 men, 11 women; mean age: 67.55 ± 6.84 years, range: 53-81 years) were included. Fourteen patients had more than two systemic diseases, and nine patients had more than three systemic diseases. The mean follow-up period was 39.05 months. Of the 60 implants, 2 failed, resulting in an implant survival rate of 96.6%. No statistical differences were found in implant survival rates according to sex, age, implant diameter, restored arch, or opposing dentition (p > 0.05). A significant difference in mean marginal bone loss (MBL) was noted for restoring the arch (p = 0.022) and opposing dentition (p = 0.036). Implants placed in the mandible and with opposing removable partial dentures and complete dentures showed lower mean MBL. No significant differences in implant MBL were observed in terms of age, sex, or implant diameter (p > 0.05). Favorable clinical outcomes can be expected from implant overdentures using two or four implants in edentulous patients with systemic diseases by ensuring that the patients have a sufficient healing period and regular checkups.

Influence of Bone-Level Dental Implants Placement and of Cortical Thickness on Osseointegration: In Silico and In Vivo Analyses

The purpose of this research is to study the biomechanical response of dental implants in bone-level type locations, 0.5 mm above and below the bone level. In addition, the influence of the thickness of the cortical bone on osseointegration is determined due to the mechanical loads transfer from the dental implant to the cortical and trabecular bone. The thicknesses studied were 1.5 mm and 2.5 mm. Numerical simulations were performed using a finite element method (FEM)-based model. In order to verify the FEM model, the in silico results were compared with the results obtained from a histological analysis performed in an in vivo study with 30 New Zealand rabbits. FEM was performed using a computerized 3D model of bone-level dental implants inserted in the lower jawbone with an applied axial load of 100 N. The analysis was performed using different distances from the bone level and different thicknesses of cortical bone. The interface area of bone growth was evaluated by analyzing the bone–implant contact (BIC), region of interest (ROI) and total bone area (BAT) parameters obtained through an in vivo histological process and analyzed by scanning electron microscopy (SEM). Bone-level implants were inserted in the rabbit tibiae, with two implants placed per tibia. These parameters were evaluated after three or six weeks of implantation. FEM studies showed that placements 0.5 mm below the bone level presented lower values of stress distribution compared to the other studied placements. The lower levels of mechanical stress were then correlated with the in vivo studies, showing that this position presented the highest BIC value after three or six weeks of implantation. In this placement, vertical bone growth could be observed up the bone level. The smallest thickness of the study showed a better transfer of mechanical loads, which leads to a better osseointegration. In silico and in vivo results both concluded that the implants placed 0.5 mm below the cortical bone and with lower thicknesses presented the best biomechanical and histological behavior in terms of new bone formation, enhanced mechanical stability and optimum osseointegration.

Comparison between Early Loaded Single Implants with Internal Conical Connection or Implants with Transmucosal Neck Design: A Non-Randomized Controlled Trial with 1-Year Clinical, Aesthetics, and Radiographic Evaluation

To evaluate the implant and prosthetic of two implants with different surfaces and neck design. Enrolled patients received bone level, 12° conical connection implants (Nobel Parallel, Nobel Biocare; NOBEL group) with anodized surface (TiUnite) and roughness of 1.35 μm, or transmucosal implant system (Prama, Sweden and Martina; PRAMA group) with convergent collar, ZIrTi surface, and roughness 1.4–1.7 μm. Both implants were made of pure grade IV titanium, with similar diameter and length, chosen according to the dentistry department availability and patient’s request. After early prosthesis delivery, patients were filled for at least one year. Outcome measures were: implant and prosthetic survival and success rates, physiological marginal bone remodeling, periodontal parameters and pink esthetic score (PES). Results: Fifteen patients were allocated and treated in each group. At the one-year follow-up, three patients dropped out, one in the NOBEL group and two in the PRAMA group. During the entire time of investigation, all implants survived and the prostheses were successful. No statistically significant differences were found in term of marginal bone loss, periodontal parameters, and aesthetics (p > 0.05). Conclusion: With the limitations of the present study, both implant systems showed successful clinical results. Finally, many other clinical and surgical variables may influenced marginal bone levels, implant survival, and periodontal parameters. More homogenous clinical trials with larger samples are needed to confirm these preliminary conclusions.

In-Vitro Investigation of Fatigue and Fracture Behavior of Transmucosal versus Submerged Bone Level Implants Used in Fixed Prosthesis

Background: The present in vitro study aimed to investigate the fatigue performance of different dental fixtures in two different emergence profiles. Biological failures are frequently reported because the problem canonly be solved by replacing a failing implant with a new one. Clinicians addressed minor mechanical failures, such as bending, loosening or the fracture of screws, abutment, or the entire prosthesis, by simply replacing or fixing them. Methods: Transmucosal and submerged bone-level dental implants underwent fatigue strength tests (statical and dynamical performance) by a standardized test: UNI EN ISO 14801:2016. Two types of emergence profiles (Premium sub-crestal straight implant with a cylindrical-shaped coronal emergence or Prama one-piece cylindrical-shape implant with transmucosal convergent neck and hyperbolic geometry) were tested, and dynamic fatigue were run to failure. Data was analyzed by a suitable statistical tool. Results: The Wöhler curve of 0.38 cm Premium group c2, appeared to be significantly different from that of the 0.38 cm Prama group c3 (nonparametric one-way ANOVA χ2 = 6; degree of freedom = 1; probability = 0.0043) but not from that of the 0.33 cm Premium group c1 (nonparametric one-way ANOVA χ2 = 0.62; degree of freedom = 1; probability = 0.4328). Fatigue performance of configuration 2 was one and a half times better than that of configuration 3. Group c3 had a better ultimate failure load (421.6 ± 12.5 N) than the other two settings i.e., c1 (324.5 ± 5.5 N) and c2 (396.3 ± 5.6) reaching almost a nonsignificant level. Conclusions: It was observed that a transmucosal implant design could provide the highest resistance to static fracture. On the other hand, an equicrestal implant design could increase dynamic endurance.

Inlay-Retained Dental Bridges—A Finite Element Analysis

Inlay-retained dental bridges can be a viable minimally invasive alternative when patients reject the idea of implant therapy or conventional retained full-coverage fixed dental prostheses, which require more tooth preparation. Inlay-retained dental bridges are indicated in patients with good oral hygiene, low susceptibility to caries, and a minimum coronal tooth height of 5 mm. The present study aims to evaluate, through the finite element method (FEM), the stability of these types of dental bridges and the stresses on the supporting teeth, under the action of masticatory forces. The analysis revealed the distribution of the load on the bridge elements and on the retainers, highlighting the areas of maximum pressure. The results of our study demonstrate that the stress determined by the loading force cannot cause damage to the prosthetic device or to abutment teeth. Thus, it can be considered an optimal economical solution for treating class III Kennedy edentation in young patients or as a provisional pre-implant rehabilitation option. However, special attention must be paid to its design, especially in the connection area between the bridge elements, because the connectors and the retainers represent the weakest parts.

A novel fully tapered, self-cutting tissue-level implant: non-inferiority study in minipigs

Objectives

To assess the osseointegration and crestal bone level maintenance of a novel fully tapered self-cutting tissue-level implant for immediate placement (test) compared to a clinically established tissue-level implant (control) in moderate bone quality.

Materials and methods

Test and control implants were compared in 3 groups, i.e., small-, medium-, and large-diameter implants in an edentulous mandibular minipig model with moderate bone quality after 12 weeks of healing. Histometrically derived bone-to-implant contact (BIC) and first bone-to-implant contact (fBIC) were subjected to statistical non-inferiority testing. Maximum insertion torque values in artificial bone were assessed for comparison.

Results

BIC values for the tests and control implants for all 3 diameters were comparable and non-inferior: small diameter (61.30 ± 10.63% vs. 54.46 ± 18.31%) (p=0.99), medium diameter (60.91 ± 14.42 vs. 54.68 ± 9.16) (p=0.55), and large diameter (45.60 ± 14.67 vs. 52.52 ± 14.76) (p=0.31). fBIC values for test implants were higher and non-inferior compared to control implants in all three groups. Test implants further showed distinctly higher maximum insertion torque values compared to control implants.

Conclusion

The investigated novel tissue-level implant is able to achieve high levels of primary and secondary implant stability under simultaneous preservation of crestal bone levels. This qualifies the studied implant as an attractive candidate for immediate placement in bone of limited quality.

Clinical relevance

This pilot pre-clinical study investigated a novel tissue-level implant for immediate placement. With the aim of translating the studied prototype into clinical application pre-clinical models, procedures and controls have been chosen with the aim of reflecting its future clinical indication and use.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-021-03912-w.

The Anatomical Conditions of the Alveolar Process of the Anterior Maxilla in Terms of Immediate Implantation-Radiological Retrospective Case Series Study

The feasibility and the level of difficulty of immediate flapless implantation depend largely on the residual alveolar bone. The purpose of the study was to determine how often immediate flapless implantation in the anterior maxilla is feasible and assess the difficulty level using cone-beam computed tomography (CBCT) scans. A radiological retrospective case series study was conducted. In total, 1200 CBCT scans from 300 consecutive patients were analyzed with dedicated planning software. Immediate flapless implants were possible in 78.33% of cases. Drilling direction was either through the apex or the palatal slope. Bimodal was conducted in 9% of the cases; only through the apex in 13.08% of the cases and in 56.25% only in the slope. In 21.67%, immediate flapless implants were excluded. The feasibility and degree of difficulty differed statistically to the disadvantage of the lateral incisors compared to the central incisors. Drilling direction caused that BASE classification reflects the difficulty level of immediate implantation. CBCT is a helpful diagnostic tool for assessing the feasibility of immediate flapless implants due to the residual bone shape and volume. BASE classification helps to determine a challenge level that may also facilitate communication and result in comparison. The alveolar bone condition allows for immediate flapless implants in most cases in the aesthetic region of the maxilla, but they should be performed by an experienced specialist with regard to the bone and soft tissue quality.

Accuracy of Computer-Assisted Dynamic Navigation as a Function of Different Intraoral Reference Systems: An In Vitro Study

The aim of this in vitro study was to determine whether the process chain influences the accuracy of a computer-assisted dynamic navigation procedure. Four different data integration workflows using cone-beam computed tomography (CBCT), conventional impressions, and intraoral digitization with and without reference markers were analyzed. Digital implant planning was conducted using data from the CBCT scans and 3D data of the oral models. The restoration of the free end of the lower jaw was simulated. Fifteen models were each implanted with two new teeth for each process chain. The models were then scanned with scan bodies screwed onto the implants. The deviations between the planned and achieved implant positions were determined. The evaluation of all 120 implants resulted in a mean angular deviation of 2.88 ± 2.03°. The mean 3D deviation at the implant shoulder was 1.53 ± 0.70 mm. No significant differences were found between the implant regions. In contrast, the workflow showed significant differences in various parameters. The position of the reference marker affected the accuracy of the implant position. The in vitro examination showed that precise implantation is possible with the dynamic navigation system used in this study. The results are of the same order of magnitude that can be achieved using static navigation methods. Clinical studies are yet to confirm the results of this study.

Decision-Making in Implantology-A Cross-Sectional Vignette-Based Study to Determine Clinical Treatment Routines for the Edentulous Atrophic Mandible

This cross-sectional study aimed to investigate the influence of possible factors in the patient history on decision making in the therapy for a severely atrophied edentulous mandible. A vignette-based survey among 250 maxillofacial and oral surgeons was conducted. Determinants that could influence the therapy decision were patient age, smoking, fear of surgery, and radiotherapy in the head and neck area (the implant region is not in the direct radiation area). To achieve a suitable implant site, the options offered to the surgeons were bone split, bone block, augmentation with bone substitute material, and bone resection. There also was the option of rejecting any therapy. The response rate was 47%. Patient age, radiotherapy, and fear of surgery did not influence the approval of a therapy. Smoking was associated with a significantly lower endorsement of a treatment. Resection was preferred by a large majority to all other forms of therapy, regardless of the four determinants. Surgeons tend to refrain from bone block transplants in older patients. In summary, it can be said that, of the four determinants, only smoking influenced treatment refusal. Bone resection is the preferred therapy independent of all determinants.

The Efficacy of Powered Oscillating Heads vs. Powered Sonic Action Heads Toothbrushes to Maintain Periodontal and Peri-Implant Health: A Narrative Review

Objectives: To compare the efficacy of rotating-oscillating heads (ORHs) VS sonic action heads (SAHs) powered toothbrushes on plaque accumulation and gingival inflammation. Methods: An electronic (MEDLINE, Embase, Inspec, PQ SciTech and BIOSIS) and a complementary manual search were made to detect eligible studies. RCTs meeting the following criteria were included: final timepoint longer than 15 days; year of publication after 2000; patients without orthodontic appliances or severe systemic/psychiatric diseases. Studies comparing two or more different types of sonic/roto-oscillating toothbrushes were excluded. Selection of articles, extraction of data, and assessment of quality were made independently by several reviewers. Results: 12 trials (1433 participants) were included. The differences between ORHs and SAHs toothbrushes were expressed as weighted mean differences (WMD) and 95% confidence intervals (CI). The heterogeneity of data was evaluated. Concerning Plaque Index, both toothbrushes obtained comparable results. Six trials of up to 3 months and at an unclear risk of bias provided significant outcomes in terms of gingival inflammation in favor of ORHs toothbrush. Evidence resulting from three trials of up to 6 months and at a high/low risk of bias stated SAHs toothbrush superiority in gingival inflammation. Conclusions: Both ORHs and SAHs toothbrushes improved the outcomes measured from the baseline. In most of the good quality trials included, SAHs toothbrush showed statistical better long-term results. Due to the shortage of investigations, no further accurate conclusions can be outlined with reference to the superiority of a specific powered toothbrush over the other.