Influence of Narrow Titanium Dental Implant Diameter on Fatigue Behavior: A Comparison between Unitary and Splinted Implants.

Background: Scientific literature lacks strong support for using narrow diameter implants (NDI) in high masticatory force areas, especially in molars. Implant splinting in cases of multiple missing teeth reduces lateral forces, improves force distribution, and minimizes stress on implants. However, no studies have evaluated the fatigue load resistance of unitary or splinted implants. Methods: This in vitro study compares five groups of new metal alloy implants, including unitary and splinted implants with varying diameters. Mechanical characterization was assessed using a BIONIX 370 testing machine (MTS, Minneapolis, MN, USA) according to ISO 14801. For each of the five study sample groups, (n = 5) specimens underwent monotonic uniaxial compression at break testing and (n = 15) cyclic loading to determine the maximum force (Fmax) and the fatigue life (LF) values. Scanning electron microscopy (SEM) was employed for the fractographic analysis of the fractured samples. Results: The Fmax values for unitary samples ranged from 196 N to 246 N, whereas the two-splinted samples displayed significantly higher values, ranging from 2439 N to 3796 N. Similarly, the LF values for unitary samples ranged from 118 N to 230 N, while the two-splinted samples exhibited notably higher values, ranging from 488 N to 759 N. Conclusions: The observed resistance difference between sample groups in terms of Fmax and LF may be due to variations in effective cross-sectional area, determined by implant diameter and number. Additionally, this disparity may indicate a potential stiffening effect resulting from the splinting process. These findings have significant implications for dental clinical practice, suggesting the potential use of splinted sets of small-sized NDI as replacements for posterior dentition (premolars and molars) in cases of alveolar bone ridge deficiencies.

Influence of the abutment height on marginal bone level changes around two-piece dental implants: Meta-analysis and trial sequential analysis of randomized clinical trials.

BACKGROUND: The focused question was: "In systemically healthy individuals with at least one two-piece dental implant, what is the efficacy of long (≥2 mm; intervention) compared with short (<2 mm; comparison) shoulder height abutments in peri-implant marginal bone level (MBL) changes at <1 year and ≥1 year reported by randomized controlled clinical trials?" MATERIALS AND METHODS: An electronic and hand search was conducted to identify RCTs published up to August 2022. The primary outcome variable was changed in MBL from implant surgery to subsequent follow-ups. Mean values and standard deviations for each study were extracted. Weighted mean differences and 95% confidence intervals were calculated. Meta-analysis for MBL changes was performed through a random-effect restricted maximum-likelihood model at early (<1 year) and late (≥1 year) stages of bone remodeling. Publication bias and sensitivity tests were also applied. Subgroup analysis was performed to further explore possible sources of heterogeneity in the estimated treatment effect. Trial sequential analysis was performed to assess the required information and false-positive results. RESULTS: Six randomized clinical trials fulfilled the inclusion/exclusion criteria and were included in the qualitative and quantitative analysis with a follow-up range from 6 to 36 months after implant surgery. Meta-analysis revealed that long abutments significantly exhibited 0.27 mm (CI 95% -0.60, 0.06) and 0.33 mm (CI 05% -0.50, -0.16) lower MBL changes compared with short ones at <1 year and ≥1 year, respectively. Subgroup meta-analysis revealed that studies with implants placed in a more subcrestal position significantly exhibited less differences in MBL changes between long and short abutments. No meta-analysis was conducted for peri-implant clinical parameters, and soft-tissue changes provided that reported data were scarce. Trial sequential analysis revealed insufficient information size to provide a definitive answer on the effect of abutment height in MBL. CONCLUSIONS: It might be cautiously concluded that two-piece implants with long abutments (≥2 mm) may display a protective role against marginal bone loss when compared with short ones (<2 mm) at <1 year and ≥1 year. A more subcrestal implant position seemed to minimize the effect of the abutment height in terms of MBL.

Keratinized mucosa changes around one-stage implants: A prospective case series.

BACKGROUND: The need of an adequate band of keratinized tissue (KT) to maintain periodontal health around teeth as well as around implants has been a debated topic over many years but still no conclusions have been drawn. OBJECTIVES: This prospective case series evaluates the changes undergone by the keratinized mucosa (KM) and the soft tissue volume around non-submerged implants before the prosthetic rehabilitation. MATERIAL AND METHODS: A total of 40 patients were included. The primary outcome was to analyze the width of the KM at both buccal and lingual aspects compared to the pre-existing KT in the edentulous ridge only in mandibular (pre)molar area. The mucogingival line was marked with a surgical pen and an intra-oral scanner was used to take the impression of the implant area the day of the surgery (T0, baseline) and before the crown placement (T1, 3 months). Buccal soft tissue volume was measured at 1, 3, and 5 mm apical to the healing abutment position and a comparison between T0 and T1 was performed. Student t-test was used according to the distribution of the data (Shapiro-Wilk). RESULTS: The mean KT width at baseline was 4.54 ± 1.31 mm at buccal side and 5.04 ± 1.88 mm at lingual side. After 3 months, the mean KM values were 3.15 ± 1.03 mm and 3.72 ± 1.56 mm at the buccal and lingual aspects, respectively. The differences, 30.6% of KM reduction buccally and 26.1% of reduction lingually, were statistically significant for both sides. CONCLUSIONS: Within the limitations of this investigation, it was observed that the KM width from the baseline to the 3 months follow up presented a significant dimensional change in both the buccal and lingual aspects, whereas buccal soft tissue volume showed an increase between baseline and follow up.

Bone-level changes around implants with 1- or 3-mm-high abutments and their relation to crestal mucosal thickness: A 1-year randomized clinical trial.

AIM: To evaluate 1-year bone-level changes around subcrestal platform-switching implants with 1 or 3 mm definitive abutments. The influence of mucosal thickness on bone-level alterations was further analysed. MATERIALS AND METHODS: Implants were placed in the posterior sextants and positioned 1.5 mm subcrestally with an abutment of 1 or 3 mm height. Final restorations were delivered after 16 weeks. Radiographic measurements of inter-proximal bone level were the primary outcome and were adjusted by vertical mucosal thickness. Peri-implant clinical conditions and resonance frequency analysis were also compared. RESULTS: A total of 65 subjects with 99 implants were analysed. The overall 1-year implant survival rate between the 1- and 3-mm groups was 96.4% and 94.4%, respectively. Statistically significant lower inter-proximal marginal bone-level changes were observed in the 3-mm group (1 mm: -0.17 ± 0.02 mm at mesial and -0.21 ± 0.02 mm distal; 3 mm: -0.03 ± 0.02 mm at mesial and -0.03 ± 0.02 mm and distal; mesial: p = .001; distal: p < .001). Initial vertical mucosal thickness was not correlated with inter-proximal marginal bone loss. CONCLUSIONS: Subcrestal implants with 3-mm abutment were associated with minimal inter-proximal bone loss. Independent of the abutment height, crestal mucosal thickness was not correlated with bone loss.

Radiographic and histological evaluation of deproteinized bovine bone mineral vs. deproteinized bovine bone mineral with 10% collagen in ridge preservation. A randomized controlled clinical trial.

OBJECTIVES: The aims of this randomized clinical trial were to compare the dimensional changes and the histological composition after using deproteinized bovine bone mineral (DBBM) or deproteinized bovine bone mineral with 10% collagen (DBBM-C) and a collagen membrane in ridge preservation procedures. MATERIAL AND METHODS: Patients who required an extraction and a subsequent implant-supported rehabilitation at a non-molar site were recruited. After extraction, a cone beam computed tomography (CBCT) was performed and sites were randomly treated either with DBBM or DBBM-C plus a collagen membrane. At 5 months, before implant placement, a second CBCT was performed and a biopsy of the area was obtained. A blinded investigator superimposed the CBCTs and performed measurements to determine bone volume changes between the two time points. Additionally, a histomorphometric analysis of the biopsies was performed in a blinded manner. RESULTS: Eleven sites belonged to the DBBM group and eleven to the DBBM-C group. All together, a significant reduction in height and width was observed at 5 months of healing, but no statistically significant differences were observed between the DBBM and the DBBM-C group. The histomorphometric analysis revealed a similar composition in terms of newly formed bone, connective tissue and residual graft particles in both groups. CONCLUSIONS: Deproteinized bovine bone mineral with 10% collagen showed a similar behaviour as DBBM not only in its capacity to minimize ridge contraction but also from a histological point of view. Thus, both graft materials seem to be suitable for ridge preservation procedures.

Interposition of a connective tissue graft or a collagen matrix to enhance wound stability - an experimental study in dogs.

AIM: The aim of this study was to evaluate the role of a connective tissue graft (CTG) or a collagen matrix (CM) interpositioned between flaps and non-shedding hard surfaces on wound stability. MATERIAL AND METHODS: Sixty bone dehiscence defects were prepared in five Beagle dogs. Three treatments were performed in 12 sites per dog: (1) repositioned flaps were sutured onto instrumented dentin surfaces (control), (2) repositioning of flaps with an interpositioned CTG and (3) repositioning of flaps with the application of a CM. To allow postoperative healing with n = 5 for 1, 3, 7 and 14 days before evaluation, the sutures were removed, incision lines retraced and tensile forces applied to the flaps. The minimum magnitude of forces required to detach the flaps from the wound bed was recorded. RESULTS: After 1 week of healing, 6 N had to be applied to disrupt flaps from their wound bed in the CTG group. In the control group, a similar magnitude of resistance was achieved after 2 weeks (6.1 N). Flap resistance to tearing was highest in the CTG group (maximum 9.1 N) 2 weeks postoperatively. On the third postoperative day, the mean tearing forces of all groups differed significantly, displaying a 50% lower resistance to tearing in the CM compared to the CTG group. In comparison, flap resistance to tearing forces established earlier and in higher magnitude in sites with an interpositioned CTG than in flaps repositioned on dentin or CM. CONCLUSIONS: Application of a CTG, sutured to a non-shedding hard surface, significantly increased flap resistance to tearing when applying disrupting forces compared to controls. A less pronounced effect was achieved by interpositioning of a CM.

Histomorphometric results in ridge preservation procedures comparing various graft materials in extraction sockets with nongrafted sockets in humans: a systematic review.

INTRODUCTION: The aim of this systematic review was to evaluate, from a histological point of view, the amount of newly formed bone in ridge preservation procedures using various graft materials in comparison with natural healing (NH) and to determine which is the ideal type of graft to be used. MATERIALS AND METHODS: A search strategy was developed to find articles in a human model published between 1990 and January 2013 in English language using MEDLINE database. RESULTS: Thirty-four articles were included in this systematic review. When comparing the percentage of newly formed bone using various grafting materials with NH, calcium sulfate, magnesium enriched hydroxyapatite, and porcine-derived bone grafts offered the best outcomes. However, due to the heterogeneity of the included studies, the search was extended to determine which type of graft resulted in greatest bone formation. CONCLUSION: When comparing ridge preservation with NH, only 3 studies encountered a greater amount of newly formed bone in the ridge preservation group, whereas the rest did not find statistically significant differences or even observed a greater percentage of newly formed bone in the control group. Therefore, more studies are needed to determine whether the use of graft materials enhances new bone formation in contrast to NH alone and to determine the most effective bone grafting material.

Finite element analysis relative to the crestal position of a 3.0-mm-diameter implant.

It has been shown that implant designs and different vertical positions have an influence on crestal bone. The purpose of this study was to use finite element (FE) analysis to biomechanically investigate the influence of the stress/strain distribution in a maxillary anterior 3.0-mm-diameter implant in relation to its apicocoronal level after oblique loading. Two different FE models, depending on implant position relative to bone crest, were applied. It can be concluded that placing the implant-abutment interface supracrestally provides decreased levels of stress and strain in the surrounding bone. However, placing the implant 0.5 mm supracrestally is also acceptable according to this analysis.

Mandibular reconstruction with tissue engineering in multiple recurrent ameloblastoma.

The aim of this paper is to present a new approach to bone regeneration in a patient with multiple recurrent ameloblastoma of the left mandibular angle. Through an extraoral approach, complete resection of the tumor was achieved. Bone marrow aspirate from the iliac crest was centrifuged to concentrate the mesenchymal cellular fraction. Based on a stereolithographic cast, titanium mesh was bent preoperatively to accurately reconstruct the mandibular angle. The mesh was filled with two blocks of xenogenic material mixed with recombinant bone morphogenetic protein 7 (BMP-7) and stem cells. Nine months later, three endosseous implants were placed in the regenerated bone to restore the patient's masticatory function. At this time, bone samples were obtained for histomorphometric analysis. New bone formation was confirmed around the particles of xenograft material. The results indicate that adequate esthetics and function may be achieved with bone marrow aspirate seeded on a scaffold obtained from bovine xenograft blocks and BMP-7. This technique attains new bone formation with sufficient quantity and quality to allow for implant placement, with decreased patient morbidity and surgical time compared to conventional reconstructive methods.

Acellular dermal matrix in soft tissue reconstruction prior to bone grafting. A case report

When hard tissue augmentation is scheduled as a part of an oral rehabilitation, prior to the treatment, it is importantto assess if the quality of the underlying gingiva at the recipient site can support the bone grafting procedure.The most frequent complication during autologous onlay grafts are wound dehiscences in the recipient site, so theintegrity of soft tissues is a basic aspect of successful reconstructive and plastic surgical procedure. Connectivetissue grafts can improve the quality and quantity of soft tissue in oral sites where a hard tissue reconstruction isgoing to take place. However, particularly when large grafts are harvested, the autogenous donor site can presentsignificant postoperative morbidity, such as necrosis of the palate fibromucosa and bone exposition, pain andbleeding. Another important limitation with the use of autogenous grafts is the limited supply of donor connectivetissue. If a large site needs to be grafted, more than one surgical procedure may be required. An Acellular DermalMatrix (ADM) graft has become increasingly popular as a substitute for donor connective tissue, eliminating thedisadvantages described for the autogenous donor graft. The amount of tissue harvested is unlimited, so it givesan option for treating patients that have inadequate harvestable tissue or that present a large defect to be treated.The outcome of using ADM as a matrix for soft tissue reconstruction 12 weeks before bone grafting can reducethe risk of exposure and failure of the bone graft (AU)

No disponible

Acellular dermal matrix in soft tissue reconstruction prior to bone grafting. A case report.

When hard tissue augmentation is scheduled as a part of an oral rehabilitation, prior to the treatment, it is important to assess if the quality of the underlying gingiva at the recipient site can support the bone grafting procedure. The most frequent complication during autologous onlay grafts are wound dehiscences in the recipient site, so the integrity of soft tissues is a basic aspect of successful reconstructive and plastic surgical procedure. Connective tissue grafts can improve the quality and quantity of soft tissue in oral sites where a hard tissue reconstruction is going to take place. However, particularly when large grafts are harvested, the autogenous donor site can present significant postoperative morbidity, such as necrosis of the palate fibromucosa and bone exposition, pain and bleeding. Another important limitation with the use of autogenous grafts is the limited supply of donor connective tissue. If a large site needs to be grafted, more than one surgical procedure may be required. An Acellular Dermal Matrix (ADM) graft has become increasingly popular as a substitute for donor connective tissue, eliminating the disadvantages described for the autogenous donor graft. The amount of tissue harvested is unlimited, so it gives an option for treating patients that have inadequate harvestable tissue or that present a large defect to be treated. The outcome of using ADM as a matrix for soft tissue reconstruction 12 weeks before bone grafting can reduce the risk of exposure and failure of the bone graft.