Consequences of Peri-Implant Bone Loss in the Occlusal Load Transfer to the Supporting Bone in terms of Magnitude of Stress, Strain, and Stress Distribution: A Finite Element Analysis.

METHODS: Three models of a single internal connection bone level-type implant inserted into a posterior mandible bone section were constructed using a 3D finite element software: one control model without marginal bone loss and two test models, both with a circumferential peri-implant bone defect, one with a 3 mm high defect and the other one 6 mm high. A 150 N static load was tested on the central fossa at 6° relative to the axial axis of the implant. RESULTS: The results showed differences in the magnitude of strain and stress transferred to the bone between models, being the higher strain found in the trabecular bone around the implant with greater marginal bone loss. Stress distribution differed between models, being concentrated at the cortical bone in the control model and at the trabecular bone in the test models. CONCLUSION: Marginal bone loss around dental implants under occlusal loading influences the magnitude and distribution of the stress transferred and the deformation of peri-implant bone, being higher as the bone loss increases.

The Impact of Compaction Force on Graft Consolidation in a Guided Bone Regeneration Model.

PURPOSE: Compaction of particulated grafts is done manually; thus, the effect of compression force on bone regeneration remains unclear. The aim of this study was to evaluate the impact of two different compression forces on the consolidation of particulated bovine hydroxyapatite. MATERIALS AND METHODS: Two titanium cylinders were fixed on the calvarium of eight New Zealand rabbits. Both defects were filled with particulated bovine hydroxyapatite subjected to a compression force of 0.7 kg/cm2 or 1.6 kg/cm2 before being covered with a resorbable collagen membrane. A handheld device that uses a spring to control the compression force applied by the plugger was used. At 6 weeks, histomorphometry of the area immediately adjacent to the calvaria bone and to the collagen membrane was performed. RESULTS: It was shown that next to the calvaria, the bone volume per tissue volume (BV/TV) was 29.0% ± 8.8% and 27.6% ± 8.2% at low and high compression force, respectively; the bone-to-biomaterial contact (BBC) was 58.2% ± 25.0% and 69.3% ± 22.9%, respectively (P > .05). In the corresponding area next to the collagen membrane, BV/TV was 4.9% ± 5.1% and 5.7% ± 4.7%, and the BBC was 18.3% ± 20.8% and 20.1% ± 15.9%, respectively (P > .05). In addition, the number and area of blood vessels were not significantly affected by compression force. CONCLUSION: Both compression forces applied resulted in similar consolidation of bovine hydroxyapatite expressed by new bone formation and vascularization based on a rabbit calvaria augmentation model.

Influence of cortical bone and implant design in the primary stability of dental implants measured by two different devices of resonance frequency analysis: An in vitro study.

BACKGROUND: This study aimed to evaluate the effect of the implant design and the presence of cortical bone in the primary stability, as well as analyze the differences between the stability measurements obtained by two different resonance frequency analysis (RFA) devices. MATERIAL AND METHODS: A total of 80 Klockner implants of two different models [40 Essential Cone implants (group A) and 40 Vega implants (group B)] were used. The implants were placed in two polyurethane blocks that simulated the mechanical properties of the maxillary bone. One block featured a layer of cortical bone that was absent from the other block. The primary stability of all implants was measured by insertion torque and RFA using two different devices: Penguin RFA and Osstell IDX. RESULTS: Primary stability was superior in the cortical bone in both torque and RFA. In the block containing cortical bone, group A implants obtained a greater insertion torque than did group B. The insertion torque was lesser in the bone lacking cortex. Regarding the ISQ of the implants, group A presented higher values in the block with cortical bone, but the values were lower in the block without cortical bone. There were no significant differences between the values obtained from the Osstell IDX and Penguin RFA. CONCLUSIONS: The presence of cortical bone positively influences the primary stability of dental implants. The design of the implant also has a statistically significant influence on implant primary stability, although the impact depends on whether there is coronal cerclage or not. There were no statistically significant differences in the implant stability measurements obtained by two different devices. Key words:Implant stability, resonance frequency analysis, torque, osstell, penguin, cortical.

Influence of time on primary stability of dental implants placed with osteotomes due to the elastic properties of peri-implant bone.

BACKGROUND/PURPOSE: The use of osteotomes as a technique for densification and expansion of the residual ridge is one of the most widely used procedures to achieve adequate peri-implant bone quantity and density. The aim of this study was to evaluate the influence of time and the elastic deformation of peri-implant bone in the primary stability of implants placed using osteotomes. MATERIALS AND METHODS: In each of 10 fresh fragments of cow rib, two implants were placed using osteotomes. The insertion torque and initial implant stability quotient (ISQ) values were measured. In the control implants, the immediate removal torque was measured, while in the test implants, after 15 min of placement, ISQ values were measured again, and the removal torque was measured. RESULTS: There were significant differences between the ISQ values and between the insertion torque and removal torque at 15 min. The ISQ values (perpendicular/parallel) increased between the initial moment (64.4 ±â€¯9/70.3 ±â€¯5.9) and 15 min (66/71.4 ±â€¯6.4). The removal torque at 15 min (12.4 ±â€¯5.8) was lower than the insertion torque (15.9 ±â€¯5.9). Compression of the trabeculae in contact with the implant placed using osteotomes was observed, as well as a greater number of trabecular fractures in the implants placed using conventional drilling. CONCLUSION: There is an increase in ISQ values of dental implants placed using osteotomes after 15 min of placement.

Efficacy of Selective Grinding Guided by an Occlusal Splint in Management of Myofascial Pain: A Prospective Clinical Trial.

BACKGROUND: For patients whose centric relation (CR) has not been considered at the start and during treatment, the task of achieving an occlusal scheme that works together with the temporomandibular joint, the muscles, and the structures of the stomatognathic apparatus becomes a major concern. OBJECTIVE: This study aims to describe a reproducible, predictable and to date unreported procedure of selective grinding guided by an occlusal splint and to analyze condylar position (CP) based on the skeletal pattern. METHODS: A total of 72 symptomatic patients (38 females and 34 males) were classified into three groups: hyperdivergent, intermediate and hypodivergent. CP was quantified by mounted casts on a measures condyle displacement (MCD) device. Helkimo index was also performed in order to assess the severity of the temporomandibular joint (TMJ) disorders attending to clinical dysfunction, occlusal state and anamnestic dysfunction. Once the stability had been obtained, the splint was progressively reduced until the maximum intercuspation (MIC) was achieved. RESULTS: The vertical displacement was found to be significantly different between the hyperdivergent and other two groups (p<0.01). Comparisons of MCD analysis before and after the selective grinding procedure identified a statistically significant difference in the horizontal and vertical CP (p<0.01) between the different groups whereas the Helkimo Index showed a clear improvement of TMJ disorders. CONCLUSION: All facial types, specially the hyperdivergent face type, showed a reduction in condylar displacement (CD) and less craniomandibular symptoms using this procedure, making it an excellent technique for clinicians.

Inyecciones Intraarticulares de Ácido Hialurónico como Alternativa a los Corticoesteroides enel Tratamiento de la Osteoartritis de la Articulación Témporomandibular: Estudio de Revisión Sistemática / Intraarticular Injections of Hyaluronic Acid as an Alternative to Corticosteroids in the Treatment of Osteoarthritis of the Temporomandibular Joint: Study of Systematic Review

El objetivo de este trabajo fue determinar la disminución del dolor y la mejora de la función en los procesos artrósicos de la ATM mediante el empleo de hialuronato de sodio o corticoides. Realización de una revisión sistemática conforme a la metodología PICO del Centro de Medicina Basada en la Evidencia de Oxford. Se formula una pregunta dirigida al objetivo fijado y se elabora una estrategia de búsqueda, empleando términos MeSH y palabras clave específicas derivados de la pregunta en la base de datos de MEDLINE de enero de 1985 hasta abril del 2016. Se consultan un total de 43 artículos, incluyendo finalmente 7 estudios clínicos controlados y aleatorizados que cumplían los criterios de inclusión y se realiza una evaluación crítica del nivel de evidencia. Se estudiaron trabajos que comparasen la eficacia del hialuronato de sodio con los corticoides en la inyección articular de las patologías artrósicas de la ATM. No se encontraron diferencias significativas en la realización de la inyección con hialuronato de sodio y corticoides. Es necesario realizar estudios con una muestra y un tiempo de seguimiento mayor. A largo plazo podría ser más eficaz el hialuronato de sodio debido a los posibles efectos adversos de los corticoides, sin embargo, no se han demostrado cambios óseos con ninguno de los tratamientos.

The aim of this study was to determine decreasing pain and improving function in TMJ osteoarthritic processes using sodium hyaluronate or corticosteroids. A systematic review was carried out based on the PICO methodology of the Centre for Evidence-Based Medicine in Oxford. A question is addressed to the fixed aim and a search strategy is developed using specific MeSH terms and key words which come from the question in the PubMed database from January 1985 to April 2016. A total of 43 articles are consulted, finally including 7 randomized controlled trials which met the inclusion criteria and a critical assessment of the level of evidence is performed. Works that compare the efficacy of sodium hyaluronate to corticosteroids in the osteoarthritic pathologies articular injection were studied. No significant differences were found when injecting the sodium hyaluronate and the corticosteroids. It is necessary to do studies with a broader sample and a longer follow-up. In the long term sodium hyaluronate could be more effective because of possible corticosteroids adverse effects; however, no bone change has been shown with either treatment.

Mechanical Characterisation and Biomechanical and Biological Behaviours of Ti-Zr Binary-Alloy Dental Implants.

The objective of the study is to characterise the mechanical properties of Ti-15Zr binary alloy dental implants and to describe their biomechanical behaviour as well as their osseointegration capacity compared with the conventional Ti-6Al-4V (TAV) alloy implants. The mechanical properties of Ti-15Zr binary alloy were characterised using Roxolid© implants (Straumann, Basel, Switzerland) via ultrasound. Their biomechanical behaviour was described via finite element analysis. Their osseointegration capacity was compared via an in vivo study performed on 12 adult rabbits. Young's modulus of the Roxolid© implant was around 103 GPa, and the Poisson coefficient was around 0.33. There were no significant differences in terms of Von Mises stress values at the implant and bone level between both alloys. Regarding deformation, the highest value was observed for Ti-15Zr implant, and the lowest value was observed for the cortical bone surrounding TAV implant, with no deformation differences at the bone level between both alloys. Histological analysis of the implants inserted in rabbits demonstrated higher BIC percentage for Ti-15Zr implants at 3 and 6 weeks. Ti-15Zr alloy showed elastic properties and biomechanical behaviours similar to TAV alloy, although Ti-15Zr implant had a greater BIC percentage after 3 and 6 weeks of osseointegration.

Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis.

The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone.