Differences in Masticatory Function in Patients with Endodontically Treated Teeth and Single-implant–supported Prostheses: A Pilot Study

Endodontic treatment and dental implants are both viable treatment options to restore a compromised dentition. How these treatments impact patients' ability to chew has not been studied. The purpose of this study was to compare various parameters of masticatory function in patients with endodontically treated teeth and single-implant supported prostheses. Fifty patients were included in this study. Twenty-five patients had mandibular molar root canals, and 25 had single implant-supported prostheses in the mandibular molar region. The natural tooth contralateral to the treated side served as the internal control. Maximum bite force, chewing efficiency, and areas of occlusal contact and near contact (ACNC) were recorded for each subject, along with a questionnaire to evaluate subjective chewing ability. When compared with contralateral controls, dental implants were found to have significantly lower maximum bite forces, reduced chewing efficiency, and smaller ACNC. Endodontically treated teeth were not statistically different than their contralateral controls. These results indicate that endodontically treated natural teeth may provide more effective occlusal contact during masticatory function compared with implant-supported restorations, leading to more efficient mastication.     

Sensory responses from loading of implants: a pilot study

PURPOSE: Osseointegrated implants lack a periodontal ligament. Nevertheless, masticatory function in subjects with implant-supported restorations appears similar to function in those with natural dentition. It is not clear how the neurophysiologic mechanisms that modulate jaw movement are associated with osseointegrated implants. This study examined the output from the inferior alveolar nerve during implant loading. MATERIALS AND METHODS: In 3 dogs, 3 premolars were extracted in the mandible and 2 endosseous titanium implants were placed, allowed to osseointegrate for 3 months, and loaded with vibration force at the threshold response for tooth vibration, at 2x threshold, and at 3x threshold. Neurophysiologic recordings were made from the inferior alveolar nerve during loading of both implants and the adjacent molar and canine. The response magnitude in action potentials in the 50- ms poststimulus period and latency of inferior alveolar afferents in milliseconds were compared following implant loading. RESULTS: Detectable inferior alveolar nerve responses were recorded following loading from both the implants and the teeth at 2x and 3x threshold. However, the response magnitude of teeth (canine, 2.38 +/- 0.18 at 2x, 2.78 +/- 0.2 at 3x; molar, 2.2 +/- 0.16 at 2x, 2.5 +/- 0.21 at 3x) was twice that of the implants (anterior, 1.3 +/- 0.12 at 2x, 1.68 +/- 0.13 at 3x; posterior, 0.8 +/- 0.1 at 2x, 1.53 +/- 0.15 at 3x). The differences in response magnitude between the teeth and implants were significant (P < .05). The latency of response was similar. DISCUSSION: Management of the occlusion for implant-supported restorations has been empirically developed. An underlying assumption has been that implant-guided jaw function lacks significant proprioception to modulate mastication and related jaw movements. This animal study provides preliminary evidence that force application to implants does elicit a proprioceptive response. CONCLUSION: Loading of implants does elicit a sensory response that can be observed in the inferior alveolar nerve. The implications are that during occlusal function, information from regions associated with the implant can provide knowledge that could potentially modulate jaw activity in a manner similar to natural teeth.     

Fabrication of a functionally generated, implant-retained fixed partial denture

Partially edentulous patients are frequently restored with implant-supported restorations between and opposing natural teeth. Differences in horizontal and vertical mobility of teeth and dental implants necessitate occlusal contact modification to create prostheses that harmonize with the opposing dentition. This article describes a functionally generated path technique to achieve optimal articulation between an implant-retained fixed partial denture and the patient's dentition.     

Dental occlusion: modern concepts and their application in implant prosthodontics

The aim of this article was to review the literature on various aspects of occlusion related to implant prosthodontics, using PubMed and the Cochrane library. Even if the number of studies on implants and prosthodontics is very large, no randomized controlled trials or Cochrane reviews were found on the possible influence of occlusal design or characteristics of occlusion on treatment outcome. Therefore, studies and articles of a lower evidence level were accepted as the main part of the review. The widely spread opinion that implants are superior to natural teeth was refuted by two recent consensus conferences, which concluded that the long-term outcome of implant restorations is not better than that of natural teeth. No controlled studies on the optimal features of a harmonious natural and/or restored occlusion, including implant prostheses, were found. Nor was there any evidence that more sophisticated methods in jaw registration, e.g., using face-bows and adjustable articulators, compared with simpler methods, will yield better clinical prosthodontic results. This article discusses, among other things, concepts of occlusion of implant-supported restorations, occlusal material, cantilevers, and occlusal risk factors. Within the limitations of the review, it was concluded that many factors can influence implant failure and peri-implant bone loss but that little is known of the relative importance of such factors. Most probably, however, occlusal factors and details of occlusion are in general of minor importance for the outcome of implant restorations. Occlusion can be managed successfully by using simple methods for jaw registration and different occlusal concepts. This article is based on a lecture presented at the Asian Academy of Osseointegration, Hiroshima, Japan, July 18, 2008     

Implant/tooth-connected restorations utilizing screw-fixed attachments: a survey of 3,096 sites in function for 3 to 14 years

Numerous problems have been reported following various therapies used to attach natural teeth to implants beneath a fixed prosthesis. This study documents the results of 843 consecutive patients treated with 1,206 natural tooth/implant-supported prostheses utilizing 3,096 screw-fixed attachments. After 3 to 14 years in function, only 9 intrusion problems were noted. All problems were associated with fractured or lost screws. This report demonstrates the efficacy of such a treatment approach when a natural tooth/implant-supported fixed prosthesis is contemplated.     

Guidelines for splinting implants

STATEMENT OF PROBLEM: Teeth and implants have different mobility patterns. Thus, it has been believed that implant-supported restorations should not be connected to natural teeth. However, this is not always the case. PURPOSE: This article presents guidelines for connection of restorative components when implant abutments and natural teeth are involved. METHODS: Methods of connection are discussed. CONCLUSION: This article presents options for splinting of prosthetic components.     

Implant-retained dentures for full-arch rehabilitation: a case report comparing fixed and removable restorations

Dental implants as abutments for full-arch restorations are a well-documented treatment modality. This report presents a case in which the patient was treated initially with fixed restorations supported by either implants or natural teeth and subsequently treated with a removable implant/telescopic crown-supported overdenture. Advantages and disadvantages of each approach are described and discussed. While the fixed restoration resulted in a functionally satisfactory treatment outcome, the patient was displeased with the esthetic appearance. The main concern was the unnaturally long tooth shape necessary to compensate for the insufficient alveolar ridge height. Replacement of the existing restoration with an implant-supported removable overdenture led to a functionally and esthetically acceptable result. When deciding whether to use a fixed or removable implant-supported full-arch restoration, a multitude of factors must be considered. Due to the possible need for additional surgical steps to enhance the esthetic appearance surrounding fixed restorations, removable implant-supported partial dentures often are the better choice.     

Photoelastic stress analysis of load transfer to implants and natural teeth comparing rigid and semirigid connectors

STATEMENT OF PROBLEM: Controversy exists regarding the connection of implants to natural teeth. PURPOSE: This simulation study measured photoelastically the biologic behavior of implants. Stress transfer patterns with variable implant support and simulated natural teeth through rigid and nonrigid connection were examined under simulated functional loads. MATERIAL AND METHODS: A photoelastic model of a human left mandible edentulous distal to first premolar was fabricated having 2 screw type implants (3.75x13 mm) embedded within the edentulous area. Two fixed prosthetic restorations were fabricated with either a nonsplinted proximal contact or a soldered proximal contact, and cast precision dowel attachment between implant areas and simulated tooth. Simulated vertical occlusal loads were applied at fixed locations on the restorations. Stresses, which developed in the supporting structure, were monitored photoelastically and recorded photographically. RESULTS: The rigid connector in the 1 implant situation caused only slightly higher stresses in the supporting structure than the nonrigid connector. The distally loaded 1 and 2 implant-supported restoration produced the highest apical stresses, which occurred at the distal implant. The rigid connector demonstrated the greatest stress transfer in the 2 implant-supported restoration. CONCLUSIONS: Lower stresses apical to the tooth or implant occurred with forces applied further from the supporting abutment. Although the least stress was observed when using a nonrigid connector, the rigid connector in particular situations caused only slightly higher stresses in the supporting structure. The rigid connector demonstrated more widespread stress transfer in the 2 implant-supported restoration. Recommendations for selection of connector design should be based on sound clinical periodontal health of a tooth and the support provided by implants.     

Provisional restorations for optimizing esthetics in anterior maxillary implants: a case report

The use of implants for the restoration of anterior missing teeth has been established and documented during the past years. However, the use of dental implants in the anterior region is a technique-sensitive procedure. The placement of implants in an ideal position is often not possible because of the lack of sufficient bone. The clinical situation can be further complicated if the teeth were lost as a result of trauma and there is possible damage to the surrounding soft and hard tissues. The restoration of lost anterior teeth and maintenance of the surrounding soft tissues with adequate surgical and prosthetic techniques are a real challenge for the clinician. The aim of this article was to report the laboratory and clinical stages in the restoration of anterior maxillary teeth, which were lost as a result of trauma with implant-supported fixed partial denture. In this case, an intraoperative transfer of the impression posts allowed the construction of provisional restorations, which were inserted at implant uncoverage surgery and contributed significantly to the creation of a better emergence profile and to the final esthetic result. CLINICAL SIGNIFICANCE: Provisional restorations are an important stage in anterior maxillary implants, allowing guided soft tissue management and creating an esthetic emergence profile.     

A retrospective evaluation of 259 single-tooth replacements by the use of Brånemark implants

PURPOSE: The main purpose of this retrospective study was to investigate the clinical outcome of the treatment with 259 consecutively placed Br?nemark system implant-supported single crowns. MATERIALS AND METHODS: There were 259 implants placed in 183 patients with a mean age of 29.8 years; 230 (89%) were placed in the maxilla and 29 (11%) were placed in the mandible. Of the prosthetic restorations, 165 were all-ceramic (68%), 79 were metal-ceramic (31%), and 4 were gold-acrylic (1%). The observation period ranged from 1 to 9 years. RESULTS: A total of 9 patients (10 implants) was lost to follow-up. There were 3 implant failures registered, one before loading and one during the first year in function; one implant fractured after 6 years in service, giving a cumulative success rate for implants of 98.3%. A total of 8 crowns was remade following prosthetic complications; otherwise, the frequency of adverse events was low. The bone loss was of the same magnitude as in other studies on Br?nemark implants as support for single crowns. In general, the soft tissue conditions around the restorations were healthy and comparable to those of the patients' natural teeth. CONCLUSION: This study confirms the favorable results presented in other studies on Br?nemark implants to support single-tooth restorations.     

Occlusion in implants: problems in clinical cases

On prosthodontic treatment with dental implants ,we have refered to crown restorations similar to natural teeth and recostructed so far. Therefore differences between implants and teeth have happened many problems. Especially, for we harmonize occlusion for implant restoration with supporting tissue, superstructure of implant prosthesis, muscles surrounding the jaw and temporomandibular joint, how should we compensate for differences between implants and teeth, and observe occlusal shift and symptom in postoperative progress? It seems that there is little evidence on the relation between implant and occulusion. While, it is necessary for examination of the problem on occlusion for implant restoration to consider mechanically risk and character of dentition. It is essential to reveal that the cause of happened problems is whether trouble of implant or risk of dentition. There has not been the consensus between parafunction and practice in prothodontics in natural dentition yet. How do implants harmonize with nonfunctional and nonphysiological force? We cannot overlook problems that the factor of surplus force affects implant restorations. In the symposium, I propounded some problems through clinical cases.     

Implant positioning when replacing the four maxillary incisors: a platform-switched treatment option

Patients do not view dental implants as an object of desire but seek a way to replace teeth that will be as cost-effective and minimally traumatic as possible. Nowadays, anterior fixed partial dentures can provide an esthetic result that is difficult to distinguish from the natural dentition. Consequently, any implant-supported prosthesis will be compared to the esthetic and functional standards set by conventional tooth-supported restorations. The restoration of the four maxillary incisors by means of an implant-supported prosthesis is one of the most challenging situations in implant dentistry. The questions of how many implants should be placed and where they should be positioned are especially important for achieving a superior end result. This article proposes and describes the placement of two platform-switched implants in the central incisor positions as a means of achieving the correct biomechanical behavior of the prosthesis, along with the best possible esthetic results.     

Complications after treatment with implant-supported fixed prostheses: a retrospective study

PURPOSE: The aim was to retrospectively evaluate the frequencies of different complications, as well as the number of visits to dentists because of such complications, after treatment with implant-supported fixed prostheses. MATERIALS AND METHODS: The study group comprised 75 patients who had been treated with implant-supported fixed prostheses 3 years earlier. All case records were scrutinized, and notes of complications in association with implants and superstructures were registered. RESULTS: The most common intervention made was occlusal adjustment/selective grinding of the prostheses. Complications in association with both implants and superstructures were fairly common. The most frequent complication was fractures of the acrylic resin matrix, including artificial acrylic resin teeth. Consultations because of periimplant mucosal inflammation were much more common among women compared to men, while complications that could be attributed to heavy loading tended to be more common in men. CONCLUSION: Complications with both implants and superstructures are fairly common after treatment with implant-supported fixed prostheses. Regular follow-ups to maintain optimal function in these patients are thus mandatory.     

Evidence-based considerations for removable prosthodontic and dental implant occlusion: a literature review

The dental literature is filled with discussions of dental occlusion, occlusal schemes, philosophies, and methods to correct and restore the diseased, worn, or damaged occlusion. Traditionally, these discussions have been empirical in nature and not based on scientific evidence. Due to the empirical nature of the literature, the study of occlusion has been extremely complex and troublesome to both pre- and post-doctoral students. The introduction of osseointegrated implants has further complicated the situation. Dentists may apply the principles of occlusion for the natural dentition directly to implant-supported and retained restorations. Although this may be successful, this rationale may result in overly complex or simplified treatment protocols and outcomes. There is an emerging body of scientific literature related to dental implant therapy that may be useful in formulating treatment protocols and prosthesis designs for implant-supported restorations. This review focuses on some of the "classic" removable prosthodontic literature and the currently available scientific literature involving removable prosthodontic occlusion and dental implant occlusion. The authors reviewed the English peer-reviewed literature prior to 1996 in as comprehensive manner as possible, and material after 1996 was reviewed electronically using MEDLINE. Electronic searches of the literature were performed in MEDLINE using key words-animal studies, case series, clinical trials, cohort studies, complete denture occlusion, dental implant function, dental implant occlusion, dental implant occlusion research, dental implant functional loading, dental implants, dental occlusion, dental occlusion research, denture function, denture occlusion, dentures, implant function, implant functional loading, implant occlusion, occlusion, and removable partial denture occlusion-in various combinations to obtain potential references for review. A total of 5447 English language titles were obtained, many of which were duplicates due to multiple searches. Manual hand searching of the MEDLINE reference list was performed to identify any articles missed in the original search.     

Evaluation of occlusal status of Japanese adults based on functional tooth units

ObjectivesAlthough extensive national oral health data on dental caries and periodontal diseases in Japan are available, few studies have assessed the occlusal status of the Japanese population, and none are based on national survey data. The presence and prosthodontic conditions of the molar region are important for masticatory function, and the functional tooth unit (FTU) approach can be used to evaluate the occlusal status. Thus, using the national oral health survey data, this study investigated the occlusal status of the Japanese population using FTU.MethodsOverall, 3,605 adults (aged ≥20 years) who participated in the 2011 Japanese national oral health survey were included. FTUs were used as indices for evaluating the occlusal status. FTUs were calculated according to sex, age group, and the number of teeth present, and their associations were further analysed.ResultsThe number of teeth present, posterior teeth, and FTUs decreased with age in both men and women. In the age group of those ≥60 years, all only natural teeth-FTU (n-FTU) and natural teeth and artificial teeth from fixed prostheses or implant-supported FTU (nif-FTU) scores were <8. The total-FTU scores of all age groups, except the 60-69 and 70-79 years age groups, were >10.ConclusionThis is the first study to use FTUs and national oral health survey data to investigate the occlusal status in the Japanese population. People aged ≥60 years who have low n-FTU or natural teeth and artificial teeth from fixed prostheses or implant-supported FTU scores or those aged 60-70 years who have the lowest total-FTU scores require careful evaluation of masticatory performance.     

前牙种植修复体美观效果的影响因素和评价方法

牙科种植体己广泛应用于临床,其留存率和成功率越来越高,很多患者开始选择种植体支持式义齿来修复口内缺失牙.随着人们对美的追求不断上升,前牙区种植修复体的美观问题也日益受到患者和口腔医生的关注.但是,有哪些因素能够影响到前牙区种植修复体的美观效果,以及如何对已完成的种植体进行比较全面的美学评价,目前学术界尚未达成共识.为此,本文就影响前牙区种植修复体美观效果的相关因素和一些正在临床使用的评价方法进行综述.     

Rehabilitation of the edentulous maxilla and mandible with fixed implant-supported restorations applying immediate functional loading: a treatment concept

The rehabilitation of the complete edentulous arch with fixed implant-supported bridges can be a particular challenge for the practitioner. In the treatment concept presented, each jaw is provided with sufficient implants to realize fixed restorations under immediate (2-3 days after surgery) functional loading. After a healing time of 40 to 60 days, the metal/resin transitionals are exchanged for definitive metal/porcelain bridgework under gnathological aspects. Fixed implant-supported bridges correspond to the arches of natural teeth and can reveal better results in function, phonation, and aesthetics than removable prostheses.     

Immediate loading of single-tooth implants: immediate versus non-immediate implantation. A clinical report

The hypothesis of the present study was that immediate loading of implant-supported restorations replacing single missing teeth could be a successful procedure. The present study compared the clinical success of immediately loaded single-tooth implants placed in fresh extraction sites to that of immediately loaded single-tooth implants placed in healed sites. From the years 1997 to 1998, 26 patients, ranging in age from 18 to 70 years, presented for the placement of 28 immediately loaded implants intended to support single-tooth ceramometal restorations. Nineteen implants were placed into fresh extraction sites, and 9 implants were placed into healed sites. Temporary prefabricated acrylic resin crowns were prepared and adjusted. At the time of traditional second-stage surgery (3 to 6 months after implantation), the implants were restored with single-tooth ceramometal prostheses. The survival rates were 82.4% and 100% for immediate and non-immediate implants, respectively. Follow-up ranged from 6 to 24 months from the day of implant placement, with a mean of 13 months for the immediate implants and 16.4 months for the non-immediate implants. Radiographic marginal bone loss after 3 to 6 months did not extend beyond the abutment-implant junction. Within the limits of the present investigation, immediate loading of single-tooth implants placed in healed sites is a possible treatment alternative. Immediate loading of single-tooth implants placed in fresh extraction sites carried a risk of failure approximating 20% in this patient population.     

Maintenance requirements of implant-supported fixed prostheses opposed by implant-supported fixed prostheses, natural teeth, or complete dentures: a 5-year retrospective study

PURPOSE: The purpose of this study was to compare the maintenance requirements of implant-supported fixed prostheses with cantilever arms in edentulous jaws when opposed by fixed prostheses of similar design, by natural teeth, or by complete dentures. MATERIALS AND METHODS: The maintenance requirements for the 5-year follow-up period were obtained by examining the dental records of 37 people. Six were provided with fixed prostheses in both arches, 22 with a fixed prosthesis in the mandible opposed by a complete denture, and 9 with a fixed prosthesis opposed by natural teeth. Everyone was treated with Nobel Biocare implants using standard implant and prosthetic protocols. RESULTS: The denture teeth and acrylic resin were repaired on 44 occasions in the group with implants in both jaws, on 14 occasions in the group with implants opposed by natural teeth, and twice in the group in which the implants were opposed by a complete denture. The group with implants in both jaws was more likely to fracture the gold-alloy framework, which occurred on six occasions. The group with implants in both jaws was significantly different from the other two groups in relation to higher incidence of fracture of the teeth and gold-alloy framework. CONCLUSION: The maintenance requirements of implant-supported fixed prostheses with cantilever arms opposed by fixed prostheses of similar design were much greater than when opposed by natural teeth or complete dentures.     

Use of a removable partial denture in the management of chronic screw loosening

Lack of posterior support can result in adverse occlusal forces being placed on anterior teeth. These forces may cause fremitus, splaying of the anterior teeth, and even accelerated wear. When implant-supported restorations are used, a common indicator of overload is screw loosening. This clinical report demonstrated conservative management of a patient who presented with multiple episodes of screw loosening of an implant-supported restoration replacing the maxillary left incisor secondary to developing reduced posterior support. Ideal treatment would be to re-establish posterior support by means of implant-supported restorations; however, this option was constrained by finances.