International Journal of Implant Dentistry最新文献

Purpose: Calcium phosphate cement (CPC) demonstrates excellent shape retention; however, the material exhibits a prolonged resorption period. Despite its inferior mechanical strength and poor shape retention, beta-tricalcium phosphate (β-TCP) offers excellent osteoconductivity. We previously reported that incorporating β-TCP into CPC enhances mechanical strength and shape retention. However, the prolonged setting time poses a challenge for clinical application. We aimed to improve the clinical usefulness of the CPC/β-TCP composite material.

Materials and methods: Samples with different mixing ratios of β-TCP (SUPERPORE) to quick-setting type of CPC (BIOPEX^®-R Quick Type) (C0, C10, C30, and C50 with mixing ratios of β-TCP of 0, 10, 30, and 50 wt%, respectively) were prepared. We evaluated the material properties. New bone formation was evaluated by histological and histopathological analysis after 4 and 8 weeks of implantation into the calvarial bone of Wistar rats.

Results: This material was set in approximately 4 min. As the β-TCP content increased, the compressive strength decreased significantly. The average compressive strength C30 was 1.5 MPa. Penetration tests confirmed good permeability for C30 and C50. In the histological study, better new bone formation was observed in the C30 and C50 at 4 and 8 weeks.

Conclusion: These results suggested that the composite material made in this study had a shorter setting time and improved penetration than that in the previous study and confirmed its biocompatibility and osteoconductivity. Its compressive strength was low; therefore, it is necessary to examine whether the material can withstand the vertical and horizontal augmentation of the jawbone.

Purpose: In immediate implant placement, both open and closed healing techniques are used, but their comparative esthetic and tissue stability outcomes remain under debate. This study aimed to evaluate and compare these two approaches to support clinical decision-making.

Methods: In this prospective, randomized controlled trial, 46 patients received a total of 48 implants, assigned to either an open healing group (n = 25) or a closed healing group (n = 23). Clinical and radiological assessments were conducted at three time points: T1 (pre-extraction), T2 (3 months post-op), and T3 (12 months post-op). The primary endpoint was the Pink Esthetic Score (PES), which assesses seven soft tissue parameters. Secondary endpoints included implant survival and volumetric tissue changes. PES was analyzed using a linear mixed-effects model.

Results: The open healing group showed significantly higher PES outcomes compared to the closed healing group (mean difference: -1.49; 95% CI: [-2.36, -0.62]; p = 0.0014). A higher baseline PES was also significantly associated with better esthetic outcomes at follow-up (0.3638, 95% CI: [0.1890, 0.5386], p = 0.0002). Smoking had no significant effect. Volumetric analysis revealed soft tissue volume loss from T1 to T2, with partial recovery by T3. Although the open healing group showed slightly less volume loss, this was not statistically significant. No implant losses occurred in either group.

Conclusion: The study demonstrated esthetic advantages of the open healing technique compared to the closed healing technique in immediate implant placement.

Purpose: To analyze how the taper angle (defined here as the half‑angle per side) influences the mechanics of the implant-abutment connection using finite element analysis.

Methods: Three‑dimensional finite element models (implant body, abutment, and screw) with taper angles of 8°, 15°, 18°, and 22° were established in ABAQUS/CAE. All components were modeled as linearly elastic Ti‑6Al‑4 V (E = 110 GPa, ν = 0.35). Frictional contact (μ = 0.3) was assigned at the taper and screw interfaces. A bolt load of 605 N (equivalent to 35 Ncm) was applied and then released to assess the press‑fit retention. Under the maintained preload, 100-N vertical and horizontal loads (unidirectional and bidirectional) were applied for five cycles. The primary outcomes are the abutment axial displacement, implant von Mises stress, bolt load change, and microgap size.

Results: Smaller taper angles (8°, 15°) retained press‑fit after preload release, whereas larger angles (18°, 22°) lost press‑fit contact. As the taper angle decreased, the abutment axial displacement, implant stresses, and bolt load loss increased. The effect of the loading direction follows the order: vertical < horizontal (unidirectional) < horizontal (bidirectional). Microgaps decreased with smaller taper angles and cycling.

Conclusion: Taper angle differences affect press-fit, abutment axial displacement, screw loosening, stress distribution, and microgap formation.

Purpose: Implants, particularly restorations with screw-retained superstructures, must have a stable passive fit. Clinical fit evaluations are often subjective. Therefore, this study investigated the feasibility of identifying misfits and evaluating the fit based on the screw-tightening torque.

Methods: Screw-retained monolithic zirconia superstructures supported by two implants and several master models were prepared. A passive-fit model was created by connecting the implant body to the superstructure and embedding it in dental stone. Vertical misfit models were created by placing titanium membranes with thicknesses of 50, 100, 150, and 200 µm between the superstructure and implant body. In each model, the screw-tightening torque on each side was measured at 0.05-s intervals up to 25 N cm. The torque for the second screw was divided into initial, middle, and final rotation phases, and the results under different conditions were compared.

Results: No vertical gaps were observed at the joints in the passive-fit model, whereas vertical gaps were observed in the misfit models. No significant differences between the accumulated torque on each side were observed in the passive fit group. By contrast, significant differences between the accumulated torque on each side were observed in the misfit groups. When the instantaneous torque was divided into three phases based on time, the samples with misfits of 150 and 200 µm showed high values in the middle and final rotation phases.

Conclusions: Passive fit and misfit can be evaluated numerically and objectively by measuring the torque and accumulated torque during the installation of screw-retained superstructures.

Purpose: Pterygoid implants are a viable alternative to sinus-lifting procedures; however, their placement may risk damaging adjacent soft tissues. This study aimed to clarify the morphology of the buccinator muscle (Bu), particularly its attachment to the pterygoid hamulus, and to assess the risk of injury during implant surgery.

Methods: Cadaveric dissection, histological analysis, and micro-computed tomography were performed. Bone morphometry was used to evaluate the maxillary tuberosity. Histological sections were analyzed to measure the distance between the Bu and the maxillary tuberosity, as well as to examine its attachment to the pterygoid hamulus.

Results: Substantial individual variation was observed in the shape and bone density of the maxillary tuberosity, with some specimens exhibiting low bone volume fraction (BV/TV). The Bu was located immediately posterior to the tuberosity at the root of the pterygoid hamulus (mean: 0.61 mm), but more distant at the tip (mean: 2.37 mm). The muscle exhibited a dual mode of attachment: tendinous at the root and periosteal at the tip. Implant perforation near the root may therefore pose a higher risk of muscle injury.

Conclusions: This study revealed a dual attachment of the buccinator muscle to the pterygoid hamulus and emphasized its close proximity to the maxillary tuberosity. Additionally, low BV/TV values in some specimens highlight the anatomical variability of this region. Understanding individual differences in bone structure and the precise location of soft tissue attachments is essential for safer and more predictable pterygoid implant placement.

Purpose: This study aimed to evaluate the safety of piezoelectric surgery for bone cutting during implant removal in terms of heat generation and histological changes.

Methods: The bone model experiments involved titanium implants or non-metal dummy implants placed in bone models. Bone cutting using a piezoelectric surgery with irrigation was performed at distances of 0, 1, and 2 mm from the implant, and the temperature was recorded using a contact thermometer placed at the tip of the implant. Using procine mandible models, histological analysis was performed using hematoxylin and eosin-stained images to evaluate the risk of thermal injury.

Results: When bone cutting was performed at distances of 0 mm from the implants continuously, a significantly greater temperature increase was observed with the titanium implants compared to the non-metal dummy implants. The increase in temperature decreased as the distance between the implant and the cutting position increased. Comparing the cutting patterns, a greater temperature increase was observed with continuous and 10 s intermittent cutting. In contrast, it was suppressed with intermittent cutting for 3 and 5 s. In the histological analysis with porcine mandibles, findings suggest that thermal injury was not observed in any of the samples.

Conclusions: No bone damage was observed in the histological analysis. In contrast, piezoelectric peri-implant bone cutting caused a significant increase in temperature, especially for continuous bone cutting during implant adjustments. However, intermittent cutting for 3 and 5 s significantly suppressed the temperature increase. The results suggest that shortening the continuous cutting time may be effective in preventing heat generation when using piezoelectric surgery for peri-implant bone cutting.

Aim: We conducted a study to investigate whether a silver nanoparticle (AgNP) coating on the surface of an implant superstructure could alter the microbiome of peri-implant tissues and to determine whether the AgNP coating would result in an improvement of gingival conditions and be effective in suppressing malodors.

Method: We conducted a single-blind, parallel group comparative study in 19 patients undergoing implant maintenance. The 9 patients in the experimental group were treated by applying an AgNP coating after ultrasonic cleaning of the implant superstructure. Ultrasonic cleaning alone was performed on the 10 patients in the control group. The efficacy of the AgNP coating was evaluated by the following procedures conducted at baseline and after 3 months: measuring the modified gingival index (mGI), analyzing odor patterns through organoleptic test and olfactometric device readings of the implant superstructure, and determining the composition of the peri-implant microbiome.Registry: the Ethics Committee for Clinical Research of Fukuoka Gakuen, TRN: 530, Registration date: 30 March 2022.

Results: The mGI values in the intervention group were significantly decreased (p = 0.043) than in the control group. In the organoleptic test, no significant intergroup differences were found in the sensory scores, but the sensory comments indicated that the odor type had changed in the experimental group. Principal component analysis (PCA) of the odor patterns at baseline and after 3 months revealed a change in the axis of the first principal component in the experimental group, but no change in the control group. A comparison of the peri-implant microbiome composition between the experimental group and the control group after three months revealed that the experimental group exhibited a significantly higher relative abundance of Neisseria oralis and Ottowia species, and a significantly lower relative abundance of Veillonella parvula, Fretibacterium fastidiosum, and Tannerella forsythia than the control group.

Conclusion: These findings suggest that the AgNP coating of the implant superstructure changed the composition of the microbiome, and that such a change may improve gingival conditions and provide a deodorizing effect.

Objective: To systematically evaluate and compare the clinical effects of the socket shield technique (SST) and conventional immediate implant placement (CIIP) in the esthetic zone through meta-analysis.

Methods: A systematic search was conducted in PubMed, EMBASE, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Chinese Science and Technology Periodical Database (VIP), and Wanfang Database for studies comparing the clinical and aesthetic effects of SST and CIIP, with the retrieval period spanning from database inception to October 9, 2024. After independent literature screening, data extraction, and bias risk assessment were independently performed by two investigations according to inclusion and exclusion criteria. All data analyses were performed by RevMan 5.4 software.

Results: A total of 27 studies, including 22 randomized controlled trials and 5 non-randomized studies of interventions (NRSI), involving 1307 implants, were included in the meta-analysis. Meta-analysis demonstrated that SST significantly outperformed CIIP in reducing horizontal buccal bone loss (MD = -0.50, 95%CI [-0.60, -0.41], I² = 97%) and vertical buccal bone loss (MD = -0.56, 95%CI [-0.64, -0.48], I = 78%), as well as improving the pink esthetic score (PES: MD = 1.25, 95%CI [0.93, 1.57], I = 90%) and implant stability quotient (ISQ: MD = 5.83, 95%CI [4.08, 7.57], I² = 69%). No significant difference was observed in implant success rate (RR = 1.00, 95% CI [0.98, 1.02], I² = 0%). Subgroup analyses (the height and thickness of buccal shield, bone grafting, and publication language) aligned with primary outcome (horizontal buccal bone loss), and sensitivity analysis confirmed stable results.

Conclusion: Based on the available evidence, SST demonstrated favorable outcomes in reducing buccal bone loss, enhancing esthetic outcomes and implant stability while maintaining comparable implant success rates to CIIP. Nevertheless, the technique exhibited technical sensitivity and a lack of standardized surgical protocols. Therefore, its clinical application should be approached with caution. Future high-quality studies with extended follow-up are required to validate long-term efficacy and establish standardized clinical guidelines.