Volumetric Changes in Morse Taper Connections After Implant Placement in Dense Bone. In-Vitro Study.

The stability of the implant-abutment interface is crucial for the maintenance of the implant index integrity. Several factors are capable of inducing deformation in implant-abutment connection, such as the actual insertion of the implant into the bone. This study aimed to evaluate the deformations produced in the connection after the insertion of the implant. Ten implants with two different implant carriers (Type A: carrier attached to platform and Type B: carrier attached inside the index-connection) were placed in artificial Type II bone, and volumetric changes were evaluated for different connection features with a 3D digital microscope. ANOVA (analysis of variance), Wilcoxon, and Tukey HSD post-test were used for statistical comparisons. Type A implants presented deformation at the platform level (inner slot angles and slot width), but no volumetric changes were observed inside the connection. Type B implants presented deformation in three parameters inside the connection (outer channel length, coronal step width, and coronal step length). Within the limitations of this study, we can conclude that more deformation is expected at the internal connection when the implant carrier engages this area. The engagement area should be as far away as possible from the index connection.

Effects of occlusal forces on the peri-implant-bone interface stability.

The occlusal forces and their influence on the initiation of peri-implant bone loss or their relationship with peri-implantitis have created discussion during the past 30 years given the discrepancies observed in clinical, animal, and finite element analysis studies. Beyond these contradictions, in the case of an osseointegrated implant, the occlusal forces can influence the implant-bone interface and the cells responsible for the bone remodeling in different ways that may result in the maintenance or loss of the osseointegration. This comprehensive review focuses on the information available about the forces transmitted through the implant-crown system to the implant-bone interface and the mechano-transduction phenomena responsible for the bone cells' behavior and their interactions. Knowledge of the basic molecular biology of the peri-implant bone would help clinicians to understand the complex phenomenon of occlusal forces and their effects on the implant-bone interface, and would allow better control of the negative effects of mechanical stresses, leading to therapy with fewer risks and complications.

Can the Macrogeometry of Dental Implants Influence Guided Bone Regeneration in Buccal Bone Defects? Histomorphometric and Biomechanical Analysis in Beagle Dogs.

The aim of this experimental animal study was to assess guided bone regeneration (GBR) and implant stability (ISQ) around two dental implants with different macrogeometries. Forty eight dental implants were placed within six Beagle dogs. The implants were divided into two groups (n = 24 per group): G1 group implants presented semi-conical macrogeometry, a low apical self-tapping portion, and an external hexagonal connection (whereby the cervical portion was bigger than the implant body). G2 group implants presented parallel walls macrogeometry, a strong apical self-tapping portion, and an external hexagonal connection (with the cervical portion parallel to the implant body). Buccal (mouth-related) defects of 2 mm (c2 condition) and 5 mm (c3 condition) were created. For the control condition with no defect (c1), implants were installed at crestal bone level. Eight implants in each group were installed under each condition. The implant stability quotient (ISQ) was measured immediately after implant placement, and on the day of sacrifice (3 months after the implant placement). Histological and histomorphometric procedures and analysis were performed to assess all samples, measuring crestal bone loss (CBL) and bone-to-implant contact (BIC). The data obtained were compared with statistical significance set at p < 0.05. The ISQ results showed a similar evolution between the groups at the two evaluation times, although higher values were found in the G1 group under all conditions. Within the limitations of this animal study, it may be concluded that implant macrogeometry is an important factor influencing guided bone regeneration in buccal defects. Group G1 showed better buccal bone regeneration (CBL) and BIC % at 3 months follow up, also parallel collar design can stimulate bone regeneration more than divergent collar design implants. The apical portion of the implant, with a stronger self-tapping feature, may provide better initial stability, even in the presence of a bone defect in the buccal area.

Infected tooth extraction, bone grafting, immediate implant placement and immediate temporary crown insertion in a patient with severe type-B hemophilia.

Haemorrhagic disorders combined with soft tissue inflammation and infection may lead to severe bleeding complications before, during or after dental treatment. In selected cases, a combined therapeutic approach involving clinical therapies and systemic and local medication could improve the treatment outcomes and the patient's quality of life. This clinical case report, presents for the first time a successful combined approach, completed in a 38-year-old male patient with severe type-B haemophilia in which an infected tooth was extracted, an immediate implant was inserted, bone grafting was performed and early implant loading was successfully applied. In addition to the clinical therapy, medication was provided orally, systemically and locally, thus preventing the haemorrhagic complications and improving the patient's quality of life.

Correction to: Influence of surface treatment on osseointegration of dental implants: histological, histomorphometric and radiological analysis in vivo.

Dear Professor Dr. Matthias Hannig. Editor-in-Chief Clinical Oral Investigations. Following the publication of our paper by Calvo Guirado et al, 2015 [1] in Clinical Oral Investigations, it came to light that a certain part of the text at the materials and methods and results sections were similar.

Correction: Peri-Implant Behavior of Sloped Shoulder Dental Implants Used for All-On-Four Protocols: An Histomorphometric Analysis in Dogs. Materials 2018, 11, 119.

The authors would like to correct following typing and two images errors [...].

The Use of Tooth Particles as a Biomaterial in Post-Extraction Sockets. Experimental Study in Dogs.

Objectives: The objective of this study was to evaluate new bone formation derived from freshly crushed extracted teeth, grafted immediately in post-extraction sites in an animal model, compared with sites without graft filling, evaluated at 30 and 90 days. Material and Methods: The bilateral premolars P2, P3, P4 and the first mandibular molar were extracted atraumatically from six Beagle dogs. The clean, dry teeth were ground immediately using the Smart Dentin Grinder. The tooth particles obtained were subsequently sieved through a special sorting filter into two compartments; the upper container isolating particles over 1200 μm, the lower container isolated particles over 300 μm. The crushed teeth were grafted into the post-extraction sockets at P3, P4 and M1 (test group) (larger and smaller post-extraction alveoli), while P2 sites were left unfilled and acted as a control group. Tissue healing and bone formation were evaluated by histological and histomorphometric analysis after 30 and 90 days. Results: At 30 days, test site bone formation was greater in the test group than the control group (p < 0.05); less immature bone was observed in the test group (25.71%) than the control group (55.98%). At 90 days, significant differences in bone formation were found with more in the test group than the control group. No significant differences were found in new bone formation when comparing the small and large alveoli post-extraction sites. Conclusions: Tooth particles extracted from dog’s teeth, grafted immediately after extractions can be considered a suitable biomaterial for socket preservation.

A new procedure for processing extracted teeth for immediate grafting in post-extraction sockets. An experimental study in American Fox Hound dogs.

OBJECTIVES: To investigate freshly extracted dental particulate used to graft post-extraction sockets in dogs, comparing new bone formation at experimental and control sites. MATERIALS AND METHODS: Bilateral premolars P2, P3, P4 and first mandibular molars were extracted atraumatically from six American Fox Hound dogs. The teeth were ground immediately using a 'Smart Dentin Grinder'. The dentin particulate was sieved to ensure a grain size of 300-1200µm and immersed in an alcohol cleanser to dissolve organic debris and bacteria, followed by washing in sterile saline buffer solution. The animals were divided into two groups randomly: group 'A' (control) samples were left to heal without any extraction socket grafting procedure; group 'B' (experimental) sockets were filled with the autogenous dentin particulate graft. The rate of tissue healing and the quantity of bone formation were evaluated using histological and histomorphometric analyses at 60 and 90 days post-grafting. The type of bone generated was categorized as woven (immature bone) or lamellar bone (mature bone). RESULTS: Substantially more bone formation was found in Group B (experimental) than Group A (control) at 60 and 90 days (p<0.05). Less immature bone was identified in the dentin grafted group (25.7%) than the control group (55.9%) [corrected]. Similar differences were also observed at 90 days post grafting. CONCLUSION: Autogenous dentin particulate grafted immediately after extractions may be considered a useful biomaterial for socket preservation, protecting both buccal and lingual plates, generating large amounts of new woven bone formation after 60 days, and small amounts of lamellar bone after 90 days healing.

Peri-Implant Behavior of Sloped Shoulder Dental Implants Used for All-On-Four Protocols: An Histomorphometric Analysis in Dogs.

The aim of this study was to evaluate the soft tissue thickness and marginal bone loss around dental implants with sloped micro-threaded shoulder (30° angle) in comparing with conventional design, inserted 30° degrees angulated in post extraction sockets and immediate loaded with temporary prosthesis simulating the all-on-four protocol. Materials and Methods: Six fox hound dogs received forty-eight post extraction dental implants with the different diameter and length (Medentika, Germany), but with different neck configurations. Two group of implants were inserted 1mm subcrestal [corrected]. Control group has a micro-threaded neck and the Test group has a sloped microthreaded neck. Immediate loading was applied using a constructed metallic structure. After three months, soft and hard tissue levels were assessed by histomorphometric analysis. Results: The mean soft tissue thickness (STT) was 2.5 ± 0.2 mm for the Control group and 3.3 ± 0.3 mm for Test group (p = 0.036), meanwhile the mean marginal bone loss (MBL) was 1.53 ± 0.34 mm for Control group and, 1.62 ± 0.22 mm for Test group (p > 0.05). Conclusions: Within the limitations of this experimental model in dogs, the findings showed that dental implants with microthreaded and microthreaded sloped necks installed in immediate post extraction sites with immediate load, presented a comparable perimplant tissue behavior.

Bone grafting materials in critical defects in rabbit calvariae. A systematic review and quality evaluation using ARRIVE guidelines.

AIMS: To perform a systematic literature review of the regenerative potential of bone substitutes used to fill critical size defects (CSDs) in rabbit calvariae; to determine the quality of the included studies using ARRIVE guidelines. MATERIAL AND METHODS: An Internet search was performed in duplicate using MEDLINE, PubMed and Google Scholar databases (without restrictions on publication date) for studies reporting the regenerative potential of bone substitutes in CSDs in rabbit calvariae. Four parameters were analyzed by histomorphometry: new bone formation (NB); defect closure (DC); residual graft (RG); and connective tissue (CT). Animal Research Reporting in In Vivo Experiments (ARRIVE) guidelines (a list of 20 aspects for scoring texts and ensuring comparison between different experimental studies in animals) were used to evaluate the quality of the selected works. RESULTS: Twenty-one manuscripts were included. CSDs with 15 mm were predominant (57.14%). Only one study described the four histomorphometric parameters. NB formation was analyzed in 15 studies (71.42%) and was higher for particulate autogenous bone grafts (range 52.1-82%) after 12 weeks. DC was evaluated in six studies (28.57%) and was higher for fragmented adipose tissue grafts (range 53.33-93.33%) after 12 weeks. RG was evaluated in four studies (19.04%) and was higher for hydroxyapatite/beta-tricalcium phosphate grafts with silica (HA/ß-TCP + Si) (range 35.78-47.54%) at 12 weeks. CT was evaluated in two studies (9.5%) and was higher for HA/ß-TCP + membrane (44.2%) at 12 weeks. Quality evaluation identified three items (title, introduction/objectives and experimental procedure) (15%) with excellent scores, 10 items (abstract, introduction/background, methods/ethical statement, experimental animals, experimental outcomes, statistics, results/baseline data, outcome/estimation and discussion interpretation/scientific implications) (50%) with average scores, and seven items (housing and husbandry, sample size, allocation, numbers analyzed, adverse effects, general applicability/relevance and funding) (35%) obtained poor scores. Only one manuscript obtained a quality evaluation considered as excellent. CONCLUSIONS: Autogenous bone grafts increase NB. DC is enhanced by the use of fragmented adipose tissue. RG remains in the defect for longer when hydroxyapatite/beta-tricalcium phosphate with silica is used, and more CT can be expected when hydroxyapatite/beta-tricalcium phosphate with silica grafts are covered by a membrane. The addition of stem cells of different origins to grafting materials enhances bone formation in early healing periods. The ARRIVE guidelines are still insufficiently used and the overall quality of studies remains low.

Retracted: A new cervical implant design compared with standard design in order to increase peri-implant hard and soft tissue behavior: histomorphometric and histological study in dogs.

OBJECTIVE: The aim of this study was to evaluate a new design of the cervical portion of dental implant with the objective to increase the volume of peri-implant tissues in the crestal area. MATERIALS AND METHODS: Forty-eight tapered dental titanium implants with internal conical connection were implanted in healed alveolar sites of six dogs. Twenty-four conventional implants design (C1 implant) formed the control group, and 24 new implant design (V3 implant) formed the test group. The groups were randomized. Histological, histomorphometric, and implant stability quotient were performed. After 12 weeks of healing period, histomorphometric analyses of the specimens were carried out to measure the crestal bone level values and the tissue thickness in the cervical implant portion. The data were compared using statistical tests (α = 5%). RESULTS: The mean of the measurements in the buccal and lingual aspects measured of crestal bone level was 0.31 ± 0.24 mm and 0.30 ± 0.19 mm in the control group, respectively, and 0.71 ± 0.28 and 0.42 ± 0.30 mm in the test group, respectively, whereas the mean of the tissue thickness was 1.63 ± 0.33 mm and 2.04 ± 0.23 mm in the control group, respectively, and 2.11 ± 0.35 mm and 2.51 ± 0.41 mm in the test group. CONCLUSIONS: Within the limitations of this study, our findings suggest that more thickness of peri-implant hard and soft tissues may be expected in this new implant design. However, the control group with traditional implant design was found to have more height values of the crestal bone compared with new V3 implants.

Influence of the implant diameter and bone quality on the primary stability of porous tantalum trabecular metal dental implants: an in vitro biomechanical study.

OBJECTIVES: The aim of this study was to evaluate the primary, initial stability of Porous Tantalum Trabecular Metal™ implants (TM) compared with Tapered Screw Vent® implants (TSV) with different diameters, inserted in two bone densities. METHODS: A total of 160 implants (80 TM and 80 TSV) with narrow (3.7 mm) and conventional (4.1 mm) diameters and the same length (10 mm) were placed in artificial bone blocks representing bone qualities II and IV. The implant stability was evaluated by insertion torque (IT) and Resonance Frequency Analysis. Statistical analysis was performed with non-parametric Kruskal-Wallis test with Dunn post-test for the differences between groups. RESULTS: The results showed higher ISQ values in dense bone compared with soft bone for all the groups (P < 0.05). Conventional-diameter implants (TSV and TM) showed higher ISQ and IT values compared with narrow implants (TSV and TM) in dense and soft bone (P < 0.05). Tapered TSV implants showed higher stability in soft bone compared with TM implants (P < 0.05). In dense bone, differences were not observed between narrow TSV 3.7 mm and TM 3.7 mm implants (P > 0.05). CONCLUSIONS: Within the limitations of this study, it can be concluded: In dense bone blocks, the wider diameter implants are more stable than narrow implants. In soft bone blocks, the tapered TSV implants are more stable than TM implants.

Dental implant surgery in patients in treatment by dabigatran.

OBJECTIVES: The aim of this study was to evaluate the incidence of bleeding complications after dental implant placement in patients in treatment by the oral anticoagulant dabigatran following a specific protocol. MATERIAL AND METHODS: Seventy-one patients were divided into two groups: 29 had been taking dabigatran for over 6 months (150 mg orally every 12 h) before implant surgery (dabigatran group) and a control group consisting of 42 healthy subjects. Patients were treated in an outpatient setting. All subjects received dental implants in different positions, dabigatran group patients 12 h after the last dose of dabigatran. Nonabsorbable sutures were used and patients were given gauzes impregnated with tranexamic acid 5% to bite on for 30-60 min. Dabigatran patients resumed medication 8 h after the procedure, resuming usual dosage (every 12 h) the day after surgery. RESULTS: Two dabigatran patients and two control patients presented slight bleeding the day after surgery. Bleeding was managed with gauzes impregnated with tranexamic acid. No statistically significant differences (P = 0.542) were found in relation to bleeding episodes between the groups, with a relative risk of 0.675 based on the pooled groups and a 95% confidence interval of 0.090-5.088. CONCLUSIONS: Dental implant surgery in patients taking dabigatran can be performed safely providing 12 h have passed since the last dose and local hemostatic measures are applied. Normal dosage can be resumed 8 h after implant surgery.

Misfit of Three Different Implant-Abutment Connections Before and After Cyclic Load Application: An In Vitro Study.

PURPOSE: This study aimed to evaluate the misfit of three different implant-abutment connections before and after cycling load. MATERIALS AND METHODS: One hundred twenty dental implants and correspondent prefabricated titanium abutments were used. Three different implant-abutment connections were evaluated: Morse taper (MT group), external hexagon (EH group), and internal hexagon (IH group). Forty implants and 40 abutments were used per group. The parameters for the mechanical evaluation were set as: 360,000 cycles, load of 150 N, and frequency of 4 Hz. Samples were sectioned in their longitudinal and transversal axes, and the misfit of the implant-abutment connection was evaluated by scanning electron microscopy analysis. One-way analyses of variance, Tukey post hoc analyses (α = .05), and t test (P < .05) were used to determine differences between groups. RESULTS: At the longitudinal direction, all the groups showed the presence of microgaps before cycling load; after cycling load, microgaps were reduced in all groups (P > .05). Transversally, only the MT group showed full fitting after cycling load compared with the other groups (EH and IH) (P < .0001). CONCLUSION: The application of cycling load produces an accommodation of the implant-abutment connection in internal, external, and Morse taper connections. In the longitudinal direction, the accommodation decreases and/or eliminates the gap observed initially (before load). In the horizontal direction, Morse cone implant-abutment connections experience a complete accommodation with the elimination of the gap.

Mechanical behavior of zirconia and titanium abutments before and after cyclic load application.

STATEMENT OF PROBLEM: Esthetic factors influence the decision to use titanium or zirconia abutments in anterior regions. Clinicians may have concerns about the durability and behavior of these zirconia abutments. PURPOSE: The purpose of this in vitro study was to evaluate the longitudinal and transverse long axes of the implant-abutment interface before and after the cyclic loading of titanium and zirconia abutments with an external hexagon. MATERIAL AND METHODS: Forty dental implants with an external hexagon and 40 corresponding abutments made of titanium (Ti) and zirconia (Zr) were subjected to cyclic load (c1) versus no load (c2). The longitudinal and transverse axes of 4 experimental groups (Tic1, Tic2, Zrc1, and Zrc2) were analyzed (vertical/horizontal adjustment) using a scanning electron microscope at ×1000 magnification. The differences among the groups were determined by 1-way analysis of variance (ANOVA) and post hoc Tukey tests (α=.05). T tests were used to identify the statistically significant differences between each group and each condition (α=.05). RESULTS: Significant differences were found among the groups with respect to the misfits analyzed in the 2 sections (longitudinal and transverse) before and after load application (P<.05). The behaviors of the groups differed particularly with regard to the accommodation of sets (abutment/implant) after the application of cyclic loads (P<.05). CONCLUSION: The use of zirconia abutments in titanium implants can cause changes to and/or permanent deformation of the implant hexagon.

Xenografts Supplemented with Pamindronate placed in postextraction sockets to avoid crestal bone resorption. Experimental study in Fox hound dogs.

OBJECTIVES: The aim of the study was to compare the effects of porcine xenografts (MP3(®)) with or without pamindronate for the healing of small and large defects of postextraction sockets. MATERIALS AND METHODS: Six beagle dogs were used in the study; second premolars and first molars of the mandible were extracted, small defects (SD) and large defects (LD) were identified. Each defect was measured and randomly filled as follows: SC (small control defects filled with MP3(®) alone), ST (small test defects filled with MP3(®) modified with pamindronate), LC (large control defects filled with MP3(®) alone), LT (large test defects filled with MP3(®) modified with pamindronate). After 4 and 8 weeks, the animals were euthanized and the percentages of new bone formation (NB), residual graft (RG) and connective tissue (CT) were analysed by histology and histomorphometry of undecalcified samples. RESULTS: After 4 weeks, NB formation was higher for ST compared to all groups and for LT compared to LC (P < 0.05); RG was significantly higher in both control groups compared to tests (P < 0.05); and CT was higher in large defects (LC and LT) compared to small defects. After 8 weeks, NB formation was higher for test groups (ST and LT) compared to controls (P < 0.05); RG was significantly higher in both control groups compared to tests (P < 0.05); and CT was higher in large defects (LC and LT) compared to small defects (P < 0.05). CONCLUSIONS: Within the limitations of this experimental study, the findings suggest that porcine xenografts modified with pamindronate favours the new bone formation and increased the porcine xenograft substitution/replacement after 4 and 8 weeks of healing.

Denosumab and osteonecrosis of the jaw. A systematic analysis of events reported in clinical trials.

OBJECTIVES: The aims of this meta-analysis were (i) to perform a systematic review of the relation between treatment with denosumab and the incidence of osteonecrosis of the jaw (ONJ) and (ii) to obtain information on dosage, first event apparition, and treatment approaches for patients with ONJ related to denosumab. MATERIALS AND METHODS: A systematic review and meta-analysis of relevant literature was performed in the PubMed, MEDLINE, Embase, and Cochrane databases, identifying randomized clinical trials that evaluate the adverse effects of denosumab. The overall incidence rates and 95% confidence intervals (CI) for ONJ were calculated employing fixed- and random-effects models, according to the heterogeneity of the studies included. RESULTS: A total of 8963 patients with a variety of solid tumors reported in seven randomized controlled trials (RCTs) were included in the systematic analysis. The overall incidence of ONJ in patients with cancer receiving denosumab was 1.7% [95% CI: 0.9-3.1%]. The use of denosumab was associated with a significantly increased risk of ONJ in comparison with bisphosphonates (BPs)/placebo treatment (RR 1.61, 95% CI: 1.05-2.48, P = 0.029). Subgroup analysis based on controlled therapies demonstrated an increased risk of ONJ in denosumab therapy, when compared with BPs (RR 1.48, 95% CI: 0.96-2.29, P = 0.078) or placebo (RR 16.28, 95% CI: 1.68-158.05, P = 0.017). Similar results were observed for prostate cancer (RR 3.358, 95% CI: 1.573-7.166, P = 0.002). CONCLUSIONS: Denosumab combined with risk factors such as dental extraction, poor oral hygiene, use of removable apparatus, and chemotherapy may favor the development of ONJ.