Occlusal Loading Research Articles

The effectiveness of prevention of occlusal disorders in dental caries

Introduction. Under the concept of occlusion, we understand the harmony between the dental arches, TMJ and neuromuscular system (masticatory muscles). Occlusal contacts play an important role in ensuring physiological occlusion. Dental caries is one of the main reason of occlusal disorders. In economically developed countries, it affects 95-98% of the population. Carious process causes changes in location of occlusal contact points, which is the reason of atypical mandibular movements. As a consequence, tooth overload and occlusal trauma are observed. Aim. The purpose of our research is a prevention of occlusal disorders by the method of composite restoration of affected occlusal surfaces considering functional anatomy with father checking of occlusal relationships with the help of computerized system T-Scan Novus. Material and methods. For this we have chosen 90 first-/second-/third-year students of Ivano-Frankivsk National Medical University at the age of 17-20, who were the citizens of the regions with low level of fluoride. Half of them had carious lesion of first molars, another 45 students had first molars, which were restored without principle of occlusion. Treatment was carried out by methods of direct and indirect restoration of occlusal surfaces taking into account the functional anatomy. Results. The article contains the results of redistribution of occlusal contact in first molar with carious lesion (decrease in the occlusal load on the affected tooth, occurrence of overload on the tooth with larger area of chewing (occlusal surface) and restoration of first molar without taking into account the principles of functional anatomy (occurrence of occlusal interferences directly on it). Further restorations of chewing surfaces of first molars considering the occlusal determinants led to an even distribution of the occlusal force on the molars. Conclusions. The obtained results of our study demonstrate the effectiveness of created treatment and prevention complex.

Occlusal concepts and considerations in implant supported prosthesis

The osseointegrated implants react biomechanically in a different pattern to occlusal force, due to lack of the periodontal ligament unlike the natural teeth. The implants show markedly less movement and limited tactile sensitivity compared with the natural teeth. The implant occlusion concept aims to avoid overloading on the implants and to direct occlusal loads along the longitudinal axis of the implants, in order to compensate for the different biomechanics of the implants. Although many guidelines and theories on implant occlusion have been proposed, few have provided strong supportive evidence. Moreover, the outcome of treatment often quite successful in spite of different concepts of occlusion and there is an increasing tendency to doubt about the strict theoretical implant-specific occlusion concept. The purpose of this article is to review the previous reports about the concept of implant occlusion and discuss clinical occlusal considerations in implant rehabilitations.

Influence of Retention Procedures on the Percentage of Occlusal Loads for Single Implant-Supported Crowns and Tooth-Supported Crowns

The purpose of this study was to investigate the influence of retention procedures on the percentage of occlusal loads experienced by single implant-supported crowns and tooth-supported crowns within the mouths of carefully selected human test subjects. Thirty subjects were selected: 20 received a single implant and full crown restoration; and 10 received a single crown restoration on a natural tooth.

Three-Dimensional Finite Element Analysis to Evaluate Stress Distribution in Tooth and Implant-Supported Fixed Partial Denture–An In Vitro Study

Abstract Introduction This study was undertaken to assess the influence of different superstructure materials, when subjected to occlusal loading, on the pattern of stress distribution in tooth-supported, implant-supported, and tooth implant-supported fixed partial prostheses, using the finite element analysis with a comparative viewpoint. Materials and Methods The geometric models of implant and mandibular bone were generated. Three models were created in accordance with the need of the study. The first model was given a tooth-supported fixed partial prosthesis. The second model was given tooth implant-supported fixed partial prosthesis, and the third model was given implant-supported fixed partial prosthesis. Forces of 100 N and 50 N were applied axially and buccolingually, respectively. Results The present study compared the stresses arising in the natural tooth, implant, and the whole prostheses under simulated axial and buccolingual loading of three types of fixed partial dentures, namely, tooth-supported, tooth implant-supported, and implant-supported fixed partial dental prostheses using three different types of materials. Conclusion The pattern of stress distribution did not appear to be significantly affected by the type of prosthesis materials in all models. The maximum stress concentrations were found in the alveolar bone around the neck of the teeth and implants.

Management of Flabby Ridge Using Hobkirk’s Technique: A Case Report

Flabby ridge is the soft mobile tissue which affects both maxillary and mandibular ridges but maxillary anterior of long term denture wearers the most. At the time of impression making, forces exerted can cause distortion of the mobile tissue. If not properly managed, denture will be displaced by the masticatory forces which will ultimately lead to loss of retention, support and stability of denture. There are many approaches to deal with displaceable denture bearing tissue “flabby ridges” which includes- Surgical management, special impression techniques, balanced distribution of occlusal loads and implant therapy. This case report presents the prosthodontic rehabilitation of a patient with flabby ridge using a different impression technique.

Swiss needle cast tolerance in British Columbia’s coastal Douglas-fir breeding population

Abstract Substantial growth losses in Douglas-fir can be the result of Swiss needle cast, a foliar disease caused by the fungus Nothophaeocryptopus gaeumannii. Although the disease is native to western North America, it is expected to become increasingly problematic in regions where climates become warmer in winter and wetter in spring, such as in coastal British Columbia (BC), Canada. Previous research suggests that tolerance to this disease is under partial genetic control. We therefore aim to screen for tolerance and resistance to the disease in the tree breeding population of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) in BC. We evaluated if early screening for resistance or tolerance to this disease is possible. We worked with 32 families grown for 18-years on two full-sibling genetic field trial sites representing different climates. We assessed >900 trees for disease signs and symptoms from 2017 to 2019. Needle retention was assessed in the field. In the laboratory, the proportion of stomata occluded with pseudothecia was measured, deoxyribonucleic acid (DNA) was extracted, and the proportion of fungal DNA in the needles was assessed using quantitative polymerase chain reaction. Strong differences were observed among families for needle retention, stomatal occlusion and fungal load. The milder and wetter site closer to the coast was generally more severely affected. Families showed rank changes between the two sites for all response variables. Higher needle retention was correlated with increased tree volume. No correlation was found between the proportion of stomata occluded with pseudothecia, fungal DNA load and needle retention. These results indicate that a more complex pathology is involved in causing needle loss. We conclude that screening for Swiss needle cast tolerance in the coastal BC Douglas-fir breeding population is possible if needle retention can be assessed and that area-specific deployment strategies may be needed given family rank changes in different environments.

Clinicians need a relining or rebasing procedure

Introduction: Complete denture serves to replace natural teeth, improve aesthetics, mastication, speech function and protect periodontal tissue. Over time of its using, denture becomes loose, so it is not comfort to use. The loose of dentures can be caused by resorption of residual ridges, systemic diseases and heavy occlusion loads result in lose of retention and stability. Management of loose dentures can be performed by relining or even rebasing the dentures. Purpose: to discuss the indication and contraindication of relining and rebasing to restore the retention and stability of loose dentures. Conclusion: Clinician must understand the indications, contraindications and materials used for the relining and rebasing procedure.

Effects of Occlusal Scheme on All-on-Four Abutments, Screws, and Prostheses: A Three-Dimensional Finite Element Study.

An ideal occlusal scheme plays an important role in a good prognosis of All-on-Four applications, as it does for other implant therapies, because of the potential impact of occlusal loads on implant prosthetic components. The aim of the present 3D finite element analysis (FEA) study was to investigate the stresses on abutments, screws, and prostheses that are generated by occlusal loads via different occlusal schemes in the All-on-Four concept. 3D models of the maxilla, mandible, implants, implant substructures, and prostheses were designed according to the All-on-Four concept. Forces were applied from the occlusal contact points formed in maximum intercuspation and eccentric movements in canine guidance occlusion (CGO), group function occlusion (GFO), and lingualized occlusion (LO). The von Mises stress values for abutment and screws and deformation values for prostheses were obtained, and results were evaluated comparatively. It was observed that the stresses on screws and abutments were more evenly distributed in GFO. Maximum deformation values for prosthesis were observed in the CFO model for lateral movement both in the maxilla and mandible. Within the limits of the present study, GFO may be suggested to reduce stresses on screws, abutments, and prostheses in the All-on-Four concept.

Rationale for Mini Dental Implant Treatment.

Mini dental implants can be used to support crowns and partial and complete dentures in compromised edentulous sites. Lack of bone width or site length may be treated with mini implants. Mini implants have less percutaneous exposure and displacement that may reduce complications. Nonetheless, mini implants transmit about twice the load to the supporting bone, and thus, control of occlusal loading is important. In fixed prosthetics, rounded flat cusps, splinting, implant protective occlusal schemes, and placement only in dense bone sites are features of successful mini implant treatment. With removable prosthetics, multiple mini implants may be needed for appropriate retention and load resistance. Maxillary lateral incisor and mandibular incisor sites may be best suited for mini implant treatment. However, past research on dental implants has been directed at standard sized implants. While mini implants are indeed dental implants, they behave somewhat differently under functional load, and the clinician should be circumspect and very judicious in their use. This article is a mini review and not a systematic review. The topics covered are not pervasive because each would require a monograph or textbook for a complete discussion.

Numerical investigation on stress intensity around Bone-Implant interface by 3-Dimensional FEA and experimental verification by optical technique

The aim of the current study is to examine numerically the stress intensity along bone-implant interface for selected implant systems under occlusal load using finite element analysis (FEA) and confirming the result experimentally by optical technique. To see the biomechanical performance at bone-implant interface the five types of implant systems are chosen for the current study. A three-dimensional (3D) computer aided design (CAD) is prepared using CreO Parametric modeling software. A non-linear contact between implant and surrounding bone is defined to analyze the stress intensity in the cancellous bone under the applied load of 100 N axial directions, 40 N laterals (Bucco-lingual) direction and 100 N oblique at 45 degree to the longitudinal axis of implant. An experimental photoelastic technique (Optical technique) is used to predict the stress intensity in a cancellous bone near the bone-implant interface using Tardy’s method of compensation. A homogeneous blend of Araldite and hardener material is used to prepare a photoelastic block model. The maximum value of stress intensity is noted in Type-I implant system at apical part of implant whereas minimum value was noted in Type-III implant system under lateral and oblique loads. Stress intensity in cancellous bone at the bone interface is found to be more significant to the applied oblique load.

Aplicabilidade do treinamento com oclusão vascular para incremento de hipertrofia e força muscular: estudo de revisão

Atualmente, diversas evidências demonstram que a prática do treinamento resistido (TR) promove hipertrofia e aumento da força muscular com cargas (kg) entre 30-80% de 1 repetição máxima (1RM). Contudo, apesar do método de treinamento com oclusão vascular (TOV) e cargas baixas ser amplamente utilizado com estas finalidades, a sua eficiência não está totalmente consolidada. Portanto, o objetivo do estudo foi verificar os efeitos do treinamento com oclusão vascular sobre a hipertrofia e força muscular. Como método foi realizado uma revisão de literatura, nas bases de dado Pubmed, LILACS e Scielo com as seguintes palavras-chave: treinamento de oclusão, Kaatsu training, oclusão vascular, treinamento resistido, blood flow restriction, Kaatsu training, resistance training. Foram incluídos artigos disponíveis em língua portuguesa e inglesa entre os anos de 2000 à 2020. Os resultados demonstraram que o método de TOV é eficiente para aumentar a hipertrofia e força muscular em diferentes populações/situações utilizando cargas baixas. Além disso, as alterações fisiológicas inerentes da oclusão vascular são eficientes na reabilitação e/ou manutenção da massa muscular durante períodos de imobilização ou incapacidade de mover o membro. Contudo, o treinamento deve ser prescrito levando em consideração a especificidade do indivíduo afim de evitar possíveis efeitos adversos.

Influence of Tooth Factors and Procedural Errors on the Incidence and Severity of Post-Endodontic Pain: A Prospective Clinical Study.

The objective of this prospective study was to assess tooth-related factors that play a role in the incidence of postoperative pain (PP) and determining if procedural errors influence PP occurrence. A total of 442 patients referred for root canal treatment met the inclusion criteria and were included in this prospective study. The same protocol was used in all root canal treatments. Patient, tooth, treatment related factors and the occurrence of procedural errors were registered. Incidence and intensity of PP was assessed at 24 and 48 h by telephonic interview and in person seven and 15 days after treatment. A logistic and ordinal regression analysis was used to assess the role of patient, tooth and treatment related factors in the incidence and intensity of PP, respectively. Preoperative and intraoperative factors differently affected the incidence of PP at the different time intervals. The presence of procedural errors did not significantly influence PP occurrence. The presence of preoperative pain and the need of additional anesthesia during treatment were associated with higher incidence of PP 24 and 48 h after treatment; the extent of apical enlargement played a significant role in the presence of PP after seven days of treatment; and the excessive occlusal load induced by the absence of a contralateral tooth was the only factor related to the maintenance of PP up to 15 days. In conclusion, the presence of preoperative pain, the need of additional anesthesia during treatment, the extent of apical enlargement and the excessive occlusal load induced by the absence of a contralateral tooth were related to a higher incidence of PP.

Biomechanical comparison of the All-on-4, M-4, and V-4 techniques in an atrophic maxilla: A 3D finite element analysis

BackgroundPatients with severely atrophied jaws can be challenging in implantology. The All-on-4 treatment concept eliminates advanced augmentation procedures in highly resorbed ridges by preserving the relevant anatomic structures. In addition, the inclination of the distal implants enables the placement of longer implants. Hence, tilting the anterior implants allows longer implant placement, in line with the distal implants of the All-on-4 concept. This study compared the biomechanical aspects of the standard All-on-4 treatment concept with the M-4 and V-4 techniques. MethodsA three-dimensional model of an edentulous maxilla was created to perform three-dimensional finite element analysis. Three different configurations (All-on-4, M-4, and V-4) were modeled by changing the tilt angle of the anterior implants. In each model, to simulate a foodstuff, a solid spherical material was placed on the midline of the incisors and the right first molar region, separately applying an occlusal load of 100 Newtons. The maximum principal stress and minimum principal stress values were acquired for cortical bone, and von Mises stress values were obtained for ductile materials. ResultsAccording to the present study's findings, although there were no considerable differences among the models, in general, the All-on-4 group demonstrated slightly higher stresses and the M-4 and V-4 group showed lower stresses. ConclusionM-4 or V-4 configurations may be used in cases of severely atrophied anterior maxillae to achieve better primary stabilization.

Influence of thermomechanical aging on marginal gap of CAD-CAM and conventional interim restorations

Statement of problemComputer-aided design and computer-aided manufacturing (CAD-CAM) milling and 3-dimensional printing are readily available for the fabrication of interim restorations. However, studies comparing the marginal gap after a long period of function are lacking. PurposeThe purpose of this in vitro study was to evaluate the marginal gap of interim crowns fabricated from different materials and with different techniques before and after receiving simulated oral stress. Material and methodsTwo conventional resins, a polymethyl methacrylate resin (Unifast Trad) and a bis-acryl resin (Protemp 4), a milled polymethyl methacrylate resin (Brylic Solid), and a 3-dimensionally printed bis-acrylate resin (Freeprint Temp) were evaluated. Interim crowns (n=10/group) were fabricated by using the conventional direct technique for Unifast Trad and Protemp 4, with a maxillary molar Dentiform tooth as a template and by using CAD-CAM for Brylic Solid and Freeprint Temp. After finishing and cementation, the marginal gap was measured at the middle of all surfaces and line angles. The average value from all 8 sites was used to represent the marginal gap of each specimen. Subsequently, all interim crowns were thermocycled (5000 cycles of 5 °C and 55 °C), and cyclic occlusal load with a 5-mm steel ball at central pit (100 000 at 100 N) and the marginal gap were remeasured. The effects of different material types and aging on marginal gap were analyzed with 2-way ANOVA. The difference in marginal gap before and after aging was analyzed by using the paired t test, and the increased marginal gap was analyzed with 1-way ANOVA (α=.05). ResultsBoth the material types and the aging regimen had a significant effect on marginal gap (P<.001). The Unifast Trad group and the Protemp 4 group had a significantly larger marginal gap than the Brylic Solid group and the Freeprint Temp group, both before and after aging (P<.01). Each group had a significantly larger marginal gap after the aging regimen (P<.001). The increased marginal gap was greatest in the Unifast Trad group, which differed statistically from the Freeprint Temp group (P=.004) but not from the other groups (P>.05). ConclusionsThe interim crowns fabricated with the Brylic Solid and the Freeprint Temp had a smaller marginal gap than those fabricated with Unifast Trad and Protemp 4, both before and after aging. The Unifast Trad group showed a significantly larger increase in marginal gap after the aging regimen than the Freeprint Temp group.

The use of finite element analysis in dentistry and orthodontics: Critical points for model development and interpreting results

Objective: This paper highlights common procedures for establishing a well-constructed FEA problem using a representative dental geometry, and discusses how results can be interpreted to understand the validity of methods and the scope over which the results are valid.Materials and Methods: A representative multi-rooted tooth geometry was generated to study the difference in mesh-density convergence when applying a 1 N occlusal force to a single node versus being distributed over a region. Additionally, a representative tooth-periodontal ligament (PDL)-bone complex was generated with a distributed 500 N occlusal load. PDL Young's modulus values were varied to demonstrate how changing properties influenced simulation outcomes.Results: The mesh density convergence study illustrated the divergent stress response when exposed to a point load as compared to the convergent response using a distributed load. Studying the tooth-PDL-bone complex showed that changing PDL properties had a substantial effect on tooth displacement and maximum stress within the PDL and nearby bone, but had less influence on stresses within the bone farther away from the PDL.Conclusions: The research illustrated the importance of proper FEA problem definition as it pertains to ensuring validity of results and that they truly reflect the overall goals of the analysis.

The Altered Cast Technique: A Case Report

The altered cast impression technique is commonly used for the mandibular distal extension partially edentulous arches. The technique is relatively simple and improves the residual ridge to dentition relationship of the prosthesis. Due to the displaceability of the mucosa, free end saddles get displaced under occlusal load. A 45-year-female patient reported to the Department Of Prosthodontics and Crown-Bridge, College of Dental Surgery, B.P. Koirala Institute of Health Sciences, Nepal with a chief complaint of missing bilateral lower posterior teeth. Clinical examination revealed missing teeth w.r.t 36, 37, 45, 46, and 47. The treatment plan was made to rehabilitate the patient with removable partial denture using functional impression along with the altered cast technique. The altered cast technique is the best alternative technique in the case of distal extension cases because better tissue adaptability, proper extension of a denture base, equal stress distribution, better support, and stability can be achieved. Finally, increased patient comfort and function are obtained.

Comparison of the outcomes of three-dimensional finite element analysis under arbitrary and realistic occlusal loading conditions in mandibular posterior region

Comparison of the outcomes of three-dimensional finite element analysis under arbitrary and realistic occlusal loading conditions in mandibular posterior region

Stress evaluation of different implant lengths on atrophic edentulous mandibles with fixed full-arch implant-supported prosthesis: a finite element analysis

Finite element analysis was used to compare the effect of different implant lengths on atrophic mandible with full-arch fixed prostheses. Four models were constructed with different implant lengths: 4, 6, 8 and 10 mm. A 100-N occlusal load was applied. The stress at the bone level, implant, and prosthetic components were obtained. Similar behavior was observed for all groups, except for 4 mm, which showed more discrepant values ​​for all prosthetic components. Although longer implants presented better biomechanical behavior, the 4 mm implant seems to be a viable alternative for severely atrophic mandibles, however, further studies need to be carried out.

ASSESSMENT OF THE PARAMETERS OF THE INTEROCCLUSION RELATIONSHIP IN THE PROCESS OF MESIALIZATION OF THE LOWER MOLARS WITH THE USE OF T-SCAN

The aim of the study. Conduct a digital analysis of the distribution of relative force occlusal load in the area of the second permanent mandibular molars before and after their mesialization.&#x0D; Research methods. In order to evaluate the distribution of inter-occlusal force load in the process of mesialization of molars on the mandible, two clinical study groups were formed. The first group consisted of 32 persons (18 women / 56.25% and 14 men / 43.75%) aged from 18 to 25 years, who had orthodontic treatment using braces and mini-implants. The second group included 30 people (19 women / 63.33% and 11 men / 36.67%), orthodontic treatment was performed using a brace system without additional intraosseous support on the mini-implants.&#x0D; T-scan apparatus investigated the distribution of relative force occlusal load in the area of the second permanent mandibular molars before and after orthodontic intervention.&#x0D; Results of the study. The use of the T-scan apparatus is an accurate and informative tool for analyzing the distribution of functional occlusal force load within the dentition. During the analysis of the parameters of the chewing load in the area of the second permanent molars on the mandible before orthodontic treatment, an increase of this index was found in almost all patients of both study groups. In the first group in 4 (12.5%) persons the maximum relative occlusive force load in the area of the second permanent molars on the mandible was 10–20%, which is the range of the norm; in 15 (46.9%) cases this indicator was 20–30. %, in 10 (31.2%) patients had 30-40%, and in 3 (9.4%) exceeded 40%. In the second group, the parameters of the relative force occlusal load in the area of the second permanent molar on the mandible were as follows: in 5 (16.7%) persons in the range of 10-20%, in 13 (43.3%) persons - 20-30%, in 10 (33.3%) patients - 30-40% and in 2 (6.7%) patients more than 40%.&#x0D; After treatment, normalization of the relative occlusal force load was observed in the area of the second permanent molars on the lower jaw in the majority of patients of both study groups. In particular, in the first group in 21 (65.6%) persons the parameters of occlusal load were in the range of 10–20%, in 11 (34.4%) persons were 20–30%. In the second study group, 17 (56.7) patients observed parameters of the occlusal load on the second molar in the range of 10-20%, in 12 (40%) persons - 20-30% and in one (3.3%) patient 30-40%.&#x0D; In addition, moving molars involves changing the usual occlusal ratios associated with the non-identity factor in the shape and size of the first and second molars.&#x0D; At the same time, occlusal contacts on all other teeth are altered due to their alignment with the orthodontic equipment and the appearance of new contact points that did not interact before the start of treatment.&#x0D; Conclusions. The analysis of the distribution of the relative occlusal load in the area of the second permanent molars on the lower jaw with the help of T-scan after orthodontic treatment revealed the normalization of this indicator in the majority of patients in both study groups. Specifically, in the first group, 21 (65.6%) subjects had parameters of relative occlusal load within the range of 10–20%, and in 11 (34.4%) individuals were 20–30%. In the second study group, 17 (56.7%) patients were in the range of 10–20%, 12 (40%) patients - 20–30% and one (3.3%) patients 30–40%. The data obtained in both the first and second study groups indicate the need to perform procedures of grinding after orthodontic intervention to achieve appropriate occlusive normalization, the volume of which in each clinical situation is determined individually under the control of the T-scan apparatus.

Investigation of a Modified Novel Technique in Bilateral Sagittal Splitting Osteotomy Fixation: Finite Element Analysis and In Vitro Biomechanical Test.

Purpose To evaluate the biomechanical properties of the modified novel 2-hole monocortical plate fixation (2HMCPf) and traditional 4-hole monocortical plate fixation (4HMCPf) techniques in bilateral sagittal splitting osteotomy (BSSO) synthesis using a finite element analysis (FEA) and an in vitro biomechanical test with the application of a shearing loading force on a sawbone mandible model. Materials and Methods A three-dimensional mandible models were generated using the geometry obtained from the computerized tomography image of a sawbone mandible. Plates and screws were generated and combined with the mandible in a CAD environment. The 2HMCPf and traditional 4HMCPf techniques for BSSO osteosynthesis were then analyzed under the occlusal load using the FEA. An in vitro biomechanical test was executed to verify the result of FEA. The force on fixation failure and pattern of failure were recorded. Results The results revealed that the von Mises Stress on the mandible cortical bone (75.98 MPa) and the screw/plate (457.19 MPa) of the 2HMCPf group was lower than that of the 4HMCPf group (987.68 MPa, 1781.59 MPa). The stress concentrated on the central region of the 4HMCPf group and the distal set of the 2HMCPf group. In vitro study using the sawbone mandible model showed mechanical failure at the region of the proximal segment near the osteotomy site with the 4HMCPf group (average 32.198 N) but no failure on the fixation sites with the 2HMCPf group. Instead, the mandible sawbone fractured on the condyle neck region (average 44.953 N). Conclusion From the biomechanical perspective, we proved that the 2HMCPf method was able to withstand a higher shearing loading force than the 4HMCPf fixation method in BSSO osteosynthesis.