Occlusal Overload Research Articles

Main risk factors in initial and late dental implant failures: a literature review

In view of the above, the purpose of the present study was to review the literature on the main risk factors for early and late failure of implants. This study used the main databases: PUBMED and ScIELO to research scientific articles written between 1981 and 2018 in Portuguese and English. In the search we used the following descriptors: Postoperative Complications, Risk Factors, Treatment Failure; Dental Implants. Therefore, 65 articles were selected in which they fit the respective inclusion criteria. The studies showed that to minimize the occurrence of initial and final failures, it is mandatory to understand the pathogenesis and risk factors, to describe the signs and symptoms, and to clarify future clinical implications; where the majority of implant studies evaluate early and late failures separately. In the analysis of initial failures, some of the causal factors most frequently reported are smoking, infection, use of short implants, systemic factors, pre-existing periodontal disease and poor bone quality and quantity. It is concluded that there are innumerous risk factors for failure of implants, be it early or late; in the early faults, the main factors include smoking, either in the anterior or posterior region of the implant, and bone quality and quantity. While in the late failures we can mention the occlusal overload, parafunctional habits, the size of the implant, with respect to the diameter and length, as well as monitoring and maintenance of the prostheses.

The Influence of Cervical Cavity Shape on the Restoration Material Retention. A finite element method study

Present study examines, by means of finite element method, the influence of cervical cavity shape on tensions distribution caused by occlusal overload of the teeth with abfraction lesion. Same force values are applied to four 3-D lower premolar finite element models, representing four different cavity shapes. An extracted lower premolar which presented an abfraction lesion has been used. The restoration was achieved by using ER adhesive systems and Giomers. The premolar was scanned and the resulting sections were processed and converted into a 3D digital format. Thus, a model of finite elements which presented a restored wedge-shaped cavity in the cervical dental area was obtained. Then, by modifying the shape and dimensions, there were created another 3 modified-shape cavities. Forces of different magnitudes (45-150N), exerted at a 45 degree angle on buccal cusp, have been applied. A wedge-shaped cavity with a short occlusal side does not show tension in the cervical region, nor in the distal angle of the restoration up to a force of 100N. So, in order to increase the retention of the abfraction restoration, changing the shape of the cavity could be the treatment of choice. Clinical relevance In order to avoid costly and unethical research, by means of FEM, different shapes of cervical cavities were easily created and conditions that influence retention of abfraction restoration were tested.

Effect of plaque accumulation and occlusal overload on peri-implant bone loss

This paper presents a case report where the influence of plaque accumulation and overload on a dental implant was observed. The patient presented crown loss on one implant affected by peri-implant bone resorption and gingival inflammation associated with poor oral hygiene. After 12 months a single crown was delivered, but as soon as the occlusal load was applied bone loss and implant failure occurred. In the present case report the dental implant remained stable as long as the implant was not loaded, although a 100% plaque index and bleeding on probing were present during the entire followup period. In contrast, as soon as an occlusal load was applied periimplant bone loss and implant failure occurred. These observations suggest that plaque accumulation alone is not a triggering factor for peri-implant bone loss and implant failure. On the contrary, occlusal load, when not properly controlled, might cause bone resorption.

Biomechanical tools to study dental implants: A literature review

Since 1980, the biomechanical behavior of dental implants has received importance regarding the issue of failure in this rehabilitation system due to occlusal overload. Through bioengineering tools, several studies have been conducted to answer about the influence of different factors on the biological response. Bioengineering tools such as finite element analysis (FEA), strain gauge (SGA), photoelasticity (PEA) and digital image correlation (DIC) are widely inspiring clinical extrapolation of possible solutions in the mechanics of implantology. This study has aimed to investigate the available stress analysis methods to study dental implants’ behavior through a literature review. This review started with a PubMed search from the mostly old studies of each methodology correlated to biomechanical behavior of dental implants used with dental implants studies until 2016. FEA, SGA, PEA and DIC methodologies are capable to elucidate the mechanical behavior of this rehabilitation system. However, the combination of two or more methods gives more detailed explanation and avoids limitations of a single methodology.

The Role of Occlusion in Implant Therapy: A Comprehensive Updated Review.

Occlusal overload may cause implant biomechanical failures, marginal bone loss, or even complete loss of osseointegration. Thus, it is important for clinicians to understand the role of occlusion in implant long-term stability. This systematic review updates the understanding of occlusion on dental implants, the impact on the surrounding peri-implant tissues, and the effects of occlusal overload on implants. Additionally, recommendations of occlusal scheme for implant prostheses and designs were formulated. Two reviewers completed a literature search using the PubMed database and a manual search of relevant journals. Relevant articles from January 1950 to September 20, 2015 published in the English language were considered. Recommendations for implant occlusion are lacking in the literature. Despite this, implant occlusion should be carefully addressed. Recommendations for occlusal schemes for single implants or fixed partial denture supported by implants include a mutually protected occlusion with anterior guidance and evenly distributed contacts with wide freedom in centric relation. Suggestions to reduce occlusal overload include reducing cantilevers, increasing the number of implants, increasing contact points, monitoring for parafunctional habits, narrowing the occlusal table, decreasing cuspal inclines, and using progressive loading in patients with poor bone quality. Protecting the implant and surrounding peri-implant bone requires an understanding of how occlusion plays a role in influencing long-term implant stability.

The Case for Smaller Diameter Implants.

Dear Editor,Previous work in the dental literature has discussed occlusal over load of dental implants in function.1 Thus larger diameter implants have been advocated.1 However, there are other considerations that may come into play that effect the longevity of an implant. The major parameters are displacement of the implant, occlusal overload, and percutaneous circumference.It may be that the actual larger displacement of large diameter implants impedes bone remodeling, especially at the crest where the bone may be thinner at the facial and lingual as compared with the deep medullary bone.2,4 Even if the crestal bone is greater than 1.8 mm the larger implant may prevent adequate angiogenesis for bone remodeling.3,5 Blood supply is important for remodeling. Large diameter implants generally have higher removal torque at initial placement and better stability than smaller diameter implants.1 However, the large physical displacement of wide diameter implants may impede bone remodeling. There may be resorption but not apposition.2 There may be a physical barrier for the blood supply that would inhibit apposition but allow resorption to occur.2,6–8Assuming, for the sake of simplicity, a length of 10 mm and the implant is a cylinder, the volume of a 5.7 mm implant is 255.047 cubic mm. The volume of a 2.5 mm × 10 mm implant, again assuming a cylinder, is 49.06 cubic mm. This larger volume may physically impede blood supply and thus impede activity of osteoclasts and osteoblasts thereby impeding remodeling, which in turn may make the cervical supporting bone and epithelial attachment susceptible to peri-implantitis.Occlusal overload is not generally an issue with large diameter implants due to the large surface area. Dental implants are capable of resisting an axial load beyond human capability. Off-axial loads, however, may not be adequately resisted by the facial or lingual cortices depending on bone quality and volume. A large diameter implant spreads any off axial loads over a larger area than small diameter thus lowering the per square millimeter load on the supporting bone.3Mini implants, <3.0 mm in diameter, may demonstrate little or no bone loss over many years of service.9 Nonetheless there is a larger per-square-millimeter load on the supporting bone. Thus control of the off-axial occlusal load is key. Nonetheless, the small surface area puts a larger per-square-millimeter load on the bone. This necessitates more dense bone or multiple splinted implants to lessen the risk for overload on the supporting bone.6–8Percutaneous circumference may put larger diameter implants at risk for peri-implantitis.2,4 Large diameter implants have a much larger percutaneous circumference as compared with small diameter implants. The small diameter/circumference may lessen the risk for late peri-implantitis. At least 1 study suggested that larger diameter implants may be more prone to peri-implantitis.5 The percutaneous circumference of a 5.7 mm implant is 15.7 mm whereas that of a 2.5 mm diameter implant is 7.85 mm, which is a dramatic difference. The smaller circumference presents less of an opportunity for invasive bacteria and less risk for any epithelial detachment and infection. 6–8Impeded remodeling and increased percutaneous exposure may increase the risk for peri-implantitis in large diameter implants. There may be less risk for peri-implantitis with small diameter implants. Large diameter implant fixtures could be more prone to late peri-implantitis. Long-term randomized controlled studies are needed to elucidate this issue. It may be appropriate to only place implants of a diameter to a maximum of 4.7 mm because larger diameters may impede bone remodeling and present a longer percutaneous exposure. It is not known what thickness, volume, or quality of bone is needed to adequately resist a given occlusal load. It may be that small diameter implants may be surprisingly able to survive long-term occlusal loads. Thus, when selecting an implant for a site, it may be better to err on the side of thin.

Evaluation of bone loss due to primary occlusal trauma in two experimental models of occlusal overload

Abstract Introduction Primary occlusal trauma (OT) is an injury of the periodontium with normal height as a result of occlusal forces which exceed their adaptive capacity. Objective To evaluate, histometrically, the alveolar bone loss in the furcation region of rats experimentally submitted to 2 models of occlusal overload. Material and method 45 animals randomly divided into 3 groups: Occlusal Interference (OI, n = 15) - fixing an orthodontic wire segment on the occlusal surface of the first lower molar; Occlusal Overload (OO, n = 15) - wearing of the cusps of the lower contralateral molars, the second and third molars next to the first molar that had its dimensions maintained; Negative Control (NC, n = 15) - evaluation of the initial dimensions of the periodontal ligament (PL). Five animals / group were sacrificed after 14, 21 and 28 days. Result Intergroup evaluation showed significant bone loss in OI (p&lt;0.001) and OO (p&lt;0.01) compared to NC. OI had significantly higher bone loss compared to OO at 14 (p&lt;0.01), 21 (p &lt;0.01) and 28 days (p&lt;0.01). The intragroup evaluation showed no significant influence of time on bone loss in OI and OO, regardless of the technique used (p&gt;0.05). The thickness of the PL remained stable in NC (p&gt;0.05). Conclusion OI and OO were effective in the experimental reproduction of OT, and OI promoted greater alveolar bone loss compared to OO, showing that the impact of occlusal overload in OI increased the extent of the OT injury.

A prospective study of the performance of resin bonded bridgework in patients with hypodontia

Congenital absence of teeth presents a number of clinical challenges in young patients, and little is known about the success rate of restorative dental treatment in these patients. The aim of this study was to conduct a prospective clinical study of the performance of resin bonded bridges in patients with hypodontia. MethodsA prospective clinical observation study was undertaken in Cork Dental School and Hospital, Ireland. Forty patients (22 males, 18 females; age range 18–21 years) with a confirmed diagnosis of hypodontia rated as mild (n=26), moderate (n=8) or severe (n=6) participated. Following completion of the orthodontic phase of care, all patients had missing teeth restored with resin bonded bridgework (RBB) using a standardised protocol (48 FF; 17CL design). Patients were followed up for 24 months, with recall visits at 6, 12 and 24 months following provision of RBBs. Results65 RBBs were provided, 49 in the maxilla and 16 in the mandible; 43 bridges replaced anterior teeth and 22 replaced posterior teeth. After 24 months, 63 bridges were still in function and deemed to satisfy the preset criteria for success and survival. Two posterior bridges had failed due to repeated debond, and this was attributed to occlusal overload. 20% of the patients demonstrated some evidence of post orthodontic relapse, but this did not require further intervention. ConclusionIn the short to medium term, resin bonded bridgework provides a reliable and minimally invasive solution for replacing missing teeth in patients with hypodontia.

Functional Role of HSP47 in the Periodontal Ligament Subjected to Occlusal Overload in Mice.

We carried out an experiment to induce traumatic occlusion in mice periodontal tissue and analyzed the expression of HSP47. Continuous traumatic occlusion resulted to damage and remodeling of periodontal ligament as well as increase in osteoclasts and bone resorption. Four days after traumatic occlusion, osteoclasts did not increase but Howship's lacunae became enlarged. That is, the persistent occlusal overload can destroy collagen fibers in the periodontal ligament. This was evident by the increased in HSP47 expression with the occlusal overload. HSP47 is maintained in fibroblasts for repair of damaged collagen fibers. On the other hand, osteoclasts continue to increase although the load was released. The osteoclasts that appeared on the alveolar bone surface were likely due to sustained activity. The increase in osteoclasts was estimated to occur after load application at day 4. HSP47 continued to increase until day 6 in experiment 2 but then reduced at day 10. Therefore, HSP47 appears after a period of certain activities to repair damaged collagen fibers, and the activity was returned to a state of equilibrium at day 30 with significantly diminished expression. Thus, the results suggest that HSP47 is actively involved in homeostasis of periodontal tissue subjected to occlusal overload.

Implant failure: A dentist's nightmare

Dental implants are commonly used in clinical situations for replacement of natural teeth. Despite many advances in materials, techniques, and implant design, implant failure is a significant concern for the dentist and patient. Peri-implantitis and lack of osseointegration are considered to be the major factors leading to implant failure. Occlusal overloading, medical status of the patient, smoking, and implant characteristics are among the other causes for implant failure. The purpose of this concise review is to discuss the etiology of implant failures by highlighting the various classification put forth by different authors and formulating a new classification.

Sinus Augmentation by Platelet-Rich Fibrin Alone: A Report of Two Cases with Histological Examinations.

In sinus floor augmentation of an atrophic posterior maxilla, platelet-rich fibrin (PRF) has been used as a graft material. We herein report two cases with histological evaluations of PRF after the surgery. The first case was a 28-year-old female with an atrophic right posterior maxilla who was treated with sinus floor augmentation and simultaneous implant placement using PRF as the sole graft material in our hospital. Twenty-four months after surgery, the implant was unfortunately removed because of occlusal overloading by parafunctional habits. During implant replacement, a tissue sample was obtained from the site of augmentation with PRF and was evaluated histologically. The second case was a 58-year-old man with severe alveolar atrophy of the right maxilla who underwent lateral sinus augmentation using only PRF in a two-stage procedure in our hospital. Samples were obtained at the second-stage surgery and histological examinations were performed. As a result, new bone formation was confirmed histologically in both cases. Our findings show that the use of PRF as a graft material during sinus floor augmentation induces natural bone regeneration.

Platform switch dental implants – Search for evidence:An overview

An implant prosthesis allows normal muscle function, and the implant stimulates the bone and maintains its dimensions in a manner similar to healthy natural teeth. Crestal bone loss can result in increased bacterial accumulation resulting in secondary periimplantitis which can further result in loss of bone support, which in turn can lead to occlusal overload resulting in implant failure. In implant dentistry, platform switching is a method used to preserve alveolar bone levels around dental implants. The concept refers to placing restorative abutment of narrower diameter on implants of wider diameter, rather than placing abutments of similar diameter, referred to as platform matching. This article is a literature overview of studies on platform switch implants and their effect on crestal bone loss.

Managing a fractured implant: A clinical report

Implant fixture fracture is one of the reasons for late implant failure, with incidence rates ranging from 0.2% to 7.5%. Material defects, occlusal overload, prosthetic design, and nonpassive prosthesis fit have been identified as causative factors for implant fixture fractures. A custom-made prosthetic post was made to connect the remaining implant fixture and the implant-retained crown, as the fractured implant fixture exhibited no signs of infection and the fixture had adequate remaining length. In addition, complete removal of the implant could have resulted in significant bone loss at the site.

Failures in Endosseous Dental Implants- A Literature review

Endosseous dental implants have become commonly used in clinical situations. Despite many advances in materials, techniques and implant design, the potential for clinical failure is a significant concern for both dentist and patient. A variety of factors can precipitate failure of an implant, including occlusal overloading,prepoperative or post operative infection and placement of implant in bone with inadequate quality and quantity. This study reviews the literature concerning the sucess or failure of an dental implants and provide the general information to dentist to decide whether to recommend dental implant to patient.

Implant for Posterior Molar with Parafunctional Habit; Cautious Approach

Bruxism is generally considered a clinical problem, which may be detrimental consequences for dental, periodontal and musculoskeletal tissues.Bruxism has also been suggested to cause excessive occlusal overload of dental implants and their superstructures, which may result in bone loss around dental implants or even in implant failure. Not surprisingly, bruxism is therefore often considered a contraindication for implant treatment, although evidence for this is usually based on clinical experience only. So far, studies to the possible cause and effect relationship between bruxism and implant failure do not yield outcomes. This is partly because of large variation in the consistent and specific literature in terms of both the technical aspects and the biological aspects of the study material. It has been documented that occlusal parafunction and lateral contacts determines the outcome of implant prosthesis. But there is no evidence for casual relation between the failures and overload of dental implants. The purpose of this report is to present an occlusal scheme, occlusal material and clinical approach for prevention of complication related to parafuntional habits.

Denture-Related Biomechanical Factors for Fixed Partial Dentures Retained on Short Dental Implants.

Prosthodontically driven biomechanical considerations are essential for longterm successful outcomes in dental implant therapy. Correct protocols seek to preclude potential consequences associated with functional and parafunctional occlusal overload such as screw loosening, component fracture, compromised marginal bone maintenance, and the integrity of the induced osseointegration response. Other concerns also need to be addressed, more especially when other implants are selected, for example: bridge insertion torque (BIT) in cases of immediate loading, cantilever length-anteroposterior spread ratio (CL-AP), overall crown-to-implant ratio (oCIR), total bone-to-implant surface area (tBICA), and the status of the opposing dentition. In spite of promising clinical results, evidence-based clinical protocols demand that such biomechanical limits still need to be determined.

Clinical considerations for appropriate occlusion of implant restorations

The appropriate occlusion is one of the most important factors for the long-term success of implant and its restorations. The purpose of this review is to investigate and define occlusal considerations to reduce failure of implant prostheses. The physiological movement of implants is markedly lower than that of natural teeth and they also lack in occlusal sensitivity. Proper occlusal pattern may be assigned to compensate for the biological disadvantages and occlusal contacts must be formed where the cantilever effect is minimized. Moreover, the long-term success of implants after osseointegration can be assured by reducing early occlusal loading to avoid implant overloading and selecting appropriate occlusion material. Occlusal overload was brought by the number and location of occlusal contacts, which are under the clinician's control. The concept of implant occlusion is based on the concepts derived from traditional prosthetics. Moreover, there are few evidence on the concept or design of implant occlusion. Several occlusal design was recommended for implant prosthesis. Mutually protected occlusion, group function occlusion and bilateral balance occlusion was recommended for the specific types of implant restorations. This article reviews proper design of occlusion for implant restoration and offers occlusion strategy clinically.

Potential use of a polycarbonate-urethane matrix reinforced with polyethylene fibers for shock-absorbing dental implants

The absence of a shock-absorbing mechanism in commercial dental implants is a likely factor in the resulting bone loss and possible implant failure. The aim of the current study is to generate a shock-absorbing dental implant that resembles the periodontal ligament, which naturally absorbs occlusal overloading forces. To achieve this, a polycarbonate-urethane composite reinforced with polyethylene fibers will be constructed. Tests based on finite element analysis and mechanical testing are proposed to further examine this novel implant type.

Flexural properties of polyethylene, glass and carbon fiber-reinforced resin composites for prosthetic frameworks

Objective. High flexural properties are needed for fixed partial denture or implant prosthesis to resist susceptibility to failures caused by occlusal overload. The aim of this investigation was to clarify the effects of four different kinds of fibers on the flexural properties of fiber-reinforced composites. Materials and methods. Polyethylene fiber, glass fiber and two types of carbon fibers were used for reinforcement. Seven groups of specimens, 2 × 2 × 25 mm, were prepared (n = 10 per group). Four groups of resin composite specimens were reinforced with polyethylene, glass or one type of carbon fiber. The remaining three groups served as controls, with each group comprising one brand of resin composite without any fiber. After 24-h water storage in 37°C distilled water, the flexural properties of each specimen were examined with static three-point flexural test at a crosshead speed of 0.5 mm/min. Results. Compared to the control without any fiber, glass and carbon fibers significantly increased the flexural strength (p < 0.05). On the contrary, the polyethylene fiber decreased the flexural strength (p < 0.05). Among the fibers, carbon fiber exhibited higher flexural strength than glass fiber (p < 0.05). Similar trends were observed for flexural modulus and fracture energy. However, there was no significant difference in fracture energy between carbon and glass fibers (p > 0.05). Conclusion. Fibers could, therefore, improve the flexural properties of resin composite and carbon fibers in longitudinal form yielded the better effects for reinforcement.

Biomechanical evaluation of Ti-Nb-Sn alloy implants with a low Young's modulus.

Dental implants are widely used and are a predictable treatment in various edentulous cases. Occlusal overload may be causally related to implant bone loss and a loss of integration. Stress concentrations may be diminished using a mechanobiologically integrated implant with bone tissue. The purpose of this study was to investigate the biomechanical behavior, biocompatibility and bioactivity of a Ti-Nb-Sn alloy as a dental implant material. It was compared with cpTi. Cell proliferation and alkaline phosphatase (ALP) activity were quantified. To assess the degree of osseointegration, a push-in test was carried out. Cell proliferation and ALP activity in the cells grown on prepared surfaces were similar for the Ti-Nb-Sn alloy and for cpTi in all the experiments. A comparison between the Ti-Nb-Sn alloy implant and the cpTi implant revealed that no significant difference was apparent for the push-in test values. These results suggest that implants fabricated using Ti-Nb-Sn have a similar biological potential as cpTi and are capable of excellent osseointegration.