Neuromuscular coordination of masticatory muscles in subjects with two types of implant-supported prostheses

OBJECTIVES: To compare the electromyographic (EMG) characteristics of masticatory muscles in patients with fixed implant-supported prostheses and implant overdentures. MATERIAL AND METHODS: Nineteen subjects aged 45-79 years were examined. Fourteen were edentulous and had been successfully rehabilitated with (a) maxillary and mandibular implant-supported fixed prostheses (seven patients); (b) mandibular implant overdentures and maxillary complete dentures (seven patients). Five control subjects had natural dentition or single/partial (no more than two teeth) tooth or implant fixed dentures. Surface EMG of the masseter and temporal muscles was performed during unilateral gum chewing and during maximum teeth clenching. To reduce biological and instrumental noise, all values were standardized as percentage of a maximum clenching on cotton rolls. RESULTS: During clenching, temporal muscle symmetry was larger in control subjects and fixed implant-supported prosthesis patients than in overdenture patients (analysis of variance, P=0.005). No differences were found in masseter muscle symmetry or in muscular torque. Muscle activities (integrated areas of the EMG potentials over time) were significantly larger in control subjects than in implant-supported prosthesis patients (P=0.014). In both patient groups, a poor neuromuscular coordination during chewing, with altered muscular patterns, and a smaller left-right symmetry than in control subjects were found (P=0.05). No differences in masticatory frequency were found. CONCLUSION: Surface EMG analysis of clenching and chewing showed that fixed implant-supported prostheses and implant overdentures were functionally equivalent. Neuromuscular coordination during chewing was inferior to that found in subjects with natural dentition.     

Electromyographic assessment of jaw muscles in patients with All‐on‐Four fixed implant‐supported prostheses

This study evaluated the electromyographic (EMG) characteristics of masticatory muscles in patients with fixed implant‐supported prostheses according to All‐on‐Four^® principles and in control healthy dentate subjects. Twenty‐six subjects aged 50–74 years were examined. Eighteen were edentulous and had been successfully rehabilitated with (i) mandibular All‐on‐Four^® implant‐supported fixed prostheses and maxillary complete dentures (10 patients) and (ii) mandibular and maxillary All‐on‐Four^® implant‐supported fixed prostheses (eight patients). Eight reference subjects had natural dentition. Surface EMG recordings of the masseter and temporalis muscles were performed during maximum voluntary teeth clenching and during unilateral gum chewing. All values were standardised as percentage of a maximum clenching on cotton rolls. During clenching, a good global neuromuscular equilibrium was found in all participants. During chewing, all groups had similar values of working‐side muscle activities and of chewing frequency. No significant differences in the analysed EMG parameters were found between the patients with mandibular and maxillary All‐on‐Four^® implant‐supported prostheses and the reference subjects. In contrast, standardised pooled muscle activities and standardised muscular activities per cycle were larger in patients with a maxillary removable prosthesis than in control subjects (Kruskal–Wallis test, P < 0·01). Also, patients wearing a complete maxillary denture showed a poor neuromuscular coordination with altered muscular pattern and lower values of the index of masticatory symmetry than dentate control subjects (P < 0·01). EMG outcomes suggest that All‐on‐Four^® implant‐supported prostheses may be considered a functionally efficient treatment option for the rehabilitation of edentulous patients with reduced residual bone volume.     

Full Mouth Rehabilitation with Maxillary Tooth Supported and Mandibular Tooth and Implant Supported Combination Prostheses: A 4-Year Case Report

The primary objectives of successful prosthetic rehabilitation are to provide function, esthetics and comfort to the patient. Combination prosthesis is one which is supported by both natural teeth and implant. The periodontal ligament and osseointegrated interface distribute force differently to the supporting bone. Therefore problems can develop when tooth and implants are combined in the same prosthesis. However, clinicians can apply biomechanical principles, to negate the deleterious leverages exerted by the fixed prosthesis by using non rigid components and to equalize the stress applied by the prosthesis on implant and teeth. A case of partially edentulous situation was rehabilitated successfully with a combination of prostheses. Maxillary arch was restored to function with crowns, fixed dental prosthesis and with an extra coronal castable attachment prosthesis and the mandibular arch with a combination of tooth and implant supported attachment prosthesis. The clinical and laboratory steps for the fabrication of these prostheses are explained in this report.     

Transition from Failing Dentition to Full‐Arch Fixed Implant‐Supported Prosthesis with a Staged Approach Using Removable Partial Dentures: A Case Series

The present retrospective case series is aimed at evaluating a staged approach using a removable partial denture (RPD) as an interim prosthesis in treatment to correct a failing dentition until such time as a full‐arch fixed implant‐supported prosthesis may be inserted. Eight patients, who had undergone maxillary full‐arch rehabilitation with dental implants due to poor prognosis of their dentitions, were analyzed. All treatment included initial periodontal therapy and a strategic order of extraction of hopeless teeth. An RPD supported by selected teeth rehabilitated the compromised arch during implant osseointegration. These remaining teeth were extracted prior to definitive prosthesis delivery. Advantages and drawbacks of this technique were also recorded for the cases presented. Among the advantages provided by the staged approach are simplicity of fabrication, low cost, and ease of insertion. Additionally, RPD tooth support prevented contact between the interim prosthesis and healing abutments, promoting implant osseointegration. The main drawbacks were interference with speech and limited esthetic results. Implant survival rate was 100% within a follow‐up of at least 1 year. The use of RPDs as interim prostheses allowed for the accomplishment of the analyzed rehabilitation treatments. It is a simple treatment alternative for patients with a low smile line.     

Perceptual Changes in the Anterior Maxilla after Placement of Endosseous Implants

Background: The innervation of skin and oral mucosa plays a major physiologic role in exteroception. It is also of interest clinically, as illustrated by sensory changes after neurosurgical procedures. Purpose: The goal of this study was to assess the perception of mechanical stimuli applied to the anterior maxilla in denture wearers and subjects rehabilitated with osseointegrated implants compared with that in subjects with a natural dentition. Materials and Methods: Five groups of subjects were selected and tested in the maxillary region only. Test groups included patients with a complete denture, an implant‐supported fixed prosthesis (full or partial), or a single‐tooth replacement. Light‐touch sensation and two‐point discrimination were performed on the buccal side of the alveolar mucosa and vibrotactile function was determined for natural teeth, full dentures, or implant‐supported prostheses. Results: For light‐touch sensation, no significant differences could be found between the groups. For two‐point discrimination, full‐denture patients showed higher threshold levels than the other groups. The threshold levels for vibrotactile function were higher in both full dentures and implant‐supported prostheses compared with natural dentitions. Conclusion: Natural dentitions offer superior vibrotactile function compared to any other dental status. Full dentures often show a stronger deterioration of the (vibro)tactile function compared with implant‐supported prostheses.     

Patient Evaluation of Treatment with Fixed Prostheses Supported by Implants or a Combination of Teeth and Implants

PURPOSE: The objective of this study was to compare treatment outcomes among subjects with complete arch fixed prostheses in the maxilla, supported by implants or a combination of natural teeth and dental implants. MATERIALS AND METHODS: Twenty-one subjects with maxillary tooth- and implant-supported fixed prostheses and 21 subjects with maxillary implant-supported fixed prostheses were identified and included in the study. All abutment teeth in the group with tooth- and implant-supported prostheses were provided with cemented copings that incorporated threads for vertical locking screws. Frameworks were fabricated with a gold alloy that was veneered with acrylic resin or ceramic materials. All frameworks were screw-retained to implants and copings. Frameworks in the group with implant-supported prostheses were fabricated with milled titanium or gold alloy to which denture teeth and resin base material were applied. All prostheses had a minimum of 8 units, at least 4 of which were in one quadrant. Subjects in both groups were mailed a questionnaire consisting of 15 questions focused on various factors related to treatment outcome, such as oral function and patient satisfaction. RESULTS: The response rate was 86%. Both groups reported a high satisfaction rate for most items with few regretting their choice of treatment. Most individuals in both groups reported great improvement in chewing ability and few reported phonetic disturbances. No statistically significant differences were found between the groups. CONCLUSION: The results of the present study showed similarity in questionnaire responses between the 2 groups of participants. High satisfaction was reported both among subjects who received a complete arch fixed prosthesis in the maxilla supported by dental implants only, as well as among those whose prostheses were supported by a combination of natural teeth and dental implants.     

Cantilever fixed prostheses utilizing dental implants: a 10-year retrospective analysis.

OBJECTIVE: The dental literature has been unclear about long-term success of fixed cantilever prostheses supported by dental implants. The disappointing results reported when cantilever fixed partial dentures (FPDs) are supported with natural teeth are not directly applicable to implant cantilever FPDs. This article reports on 10 years of implant-retained fixed prostheses primarily in the maxillary arch using the ITI dental implant system. METHOD AND MATERIALS: Sixty cantilever prostheses using 115 ITI dental implants on 36 patients were placed and monitored over a 10-year period. RESULTS: No implant fractures, abutment fractures, porcelain fractures, prosthesis fractures, soft tissue recession, or radiographic bone loss were recorded. All 60 cantilevered prostheses remain in satisfactory function. CONCLUSION: Positive, long-term results, using implant-retained cantilever FPDs can be achieved by: (1) using a rough surface implant of 4.1 mm or greater; (2) using an implant/abutment design that reduces stacked moving parts and reduces the implant-to-crowns ratio; and (3) using a cementable prosthesis design that eliminates the need for occlusal screw retention.     

Individual Lithium Disilicate Crowns in a Full‐Arch,Implant‐Supported Rehabilitation: A Clinical Report

This clinical report presents the clinical outcome of a maxillary full‐arch implant‐supported fixed rehabilitation with lithium disilicate reinforced glass ceramic monolithic crowns opposing a mandibular metal‐acrylic implant‐supported fixed rehabilitation in a 62‐year‐old woman. Eight implants were successfully placed (four maxillary, four mandibular), and no complications occurred in the postoperative or maintenance periods. Six months after delivery, the maxillary and mandibular prostheses were found to be clinically, biologically, and mechanically stable, and the patient was satisfied with the esthetics and her ability to function. Although the present indications for the use of lithium disilicate are still restricted to tooth‐borne restorations, it is possible to successfully rehabilitate edentulous patients through implant‐supported fixed prostheses using lithium disilicate reinforced glass ceramic monolithic crowns.     

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.     

Evaluation of speech in patients rehabilitated with various oral implant-supported prostheses

In the present study, speech function was assessed in edentulous patients wearing fixed or removable dental prostheses supported or not by oral implants. A total of 138 patients participated in the present research. The experimental group (n=113) was divided in 4 subgroups. Subgroup FD/FFPi comprised 22 patients with a maxillary full denture (=FD) and a mandibular fixed full prosthesis on implants (=FFPi). Subgroup FFPi/ND consisted of 27 patients with a maxillary fixed full prosthesis on implants and a natural dentition (=ND) in the mandible. Subgroup FD/ODi included 49 patients wearing a maxillary full denture and a mandibular overdenture on 2 implants (=ODi). Subgroup FFPi/FFPi comprised 15 patients having a fixed full prosthesis on implants in both jaws. The outcome of the logopedic screening of the experimental group was compared with that of a control group of subjects having a natural dentition (ND/ND; n=25). A standard clinical procedure for evaluation of speech was carried out by a speech pathologist. Besides, specific oral and prosthetic parameters were scored in all patients. It was established that one or more pronunciation difficulties occurred in 84% of the patients of the experimental group. This was significantly more than in the control group, where half the number of subjects had some speech deficiencies. No clear influence of specific oral and prosthetic parameters could be identified. From the present results, it could be concluded that in patients rehabilitated with oral implant-supported prostheses speech disorder is more frequently observed than in subjects with a natural dentition.     

Combination of natural teeth and osseointegrated implants as prosthesis abutments: a 2-year longitudinal study.

Twenty-three patients with Kennedy Class I mandibular dentition were supplied with prostheses in the posterior parts of the mandible. On one side they were given a prosthesis supported by two implants (prosthesis Type I) and on the other side they received a prosthesis supported by one implant and one natural tooth (prosthesis Type II). Sixty-nine fixtures were inserted and 46 prostheses constructed. Eight of the fixtures were lost during the observation period. The failure rate of the implants was about the same in the two types of prostheses; five fixtures belonged to prostheses Type I (10.9%) and two fixtures belonged to prostheses Type II (8.7%), while one fixture was lost prior to loading. From a theoretical point of view, the combination of a tooth and an osseointegrated implant should encounter problems with regard to the difference in bone anchorage and there should be a risk of biomechanical complications. However, the results of this study did not indicate any disadvantages in connecting teeth and implants in the same restoration.     

AICRG, Part IV: Patient satisfaction reported for Ankylos implant prostheses

PROBLEM: Although many maxillary dentures exhibit sufficient retention and stability for patients to adapt well to them, mandibular dentures present a major challenge. The introduction of the endosseous dental implant provided the opportunity for the patient to have esthetic replacements (implant prostheses) that were retentive and stable for all missing natural teeth. METHOD: This paper reports on the satisfaction of over 470 patients with implant prostheses fabricated using a new and innovative implant design (Ankylos, Dentsply-Friadent, Mannheim, Germany). RESULTS: A total of 1500 Ankylos implants were placed, restored, and followed for 3 to 5 years. Patients were asked to respond to a series of questions related to their satisfaction with their new replacements for missing natural teeth. A total of 95.6% of the patients rated chewing ability with Ankylos prosthesis as excellent to good; 92.2% indicated a significant improvement in their ability to chew; 92.6% reported overall clinical function much better than conventional dentures; 99.1% indicated that speech had improved or was not changed; 96.3% indicated hot and cold foods tasted better; 98.8% indicated no pain or discomfort during clinical function; 99.4% liked their new implant prosthesis; 98.0% would seek implant-prostheses treatment again, if necessary; 99.1% would recommend implant prostheses to friends and relatives; and 98.8% indicated the advantages of Ankylos prostheses far exceeded any disadvantages that may exist. CONCLUSIONS: Patients indicated that they (1) were highly satisfied with the final results of the replacements for their natural teeth that were retained or supported by this new implant design, (2) would not hesitate to recommend this form of treatment to their friends and relatives, and (3) would not hesitate to seek the same treatment again if necessary in the future.     

A 30‐Year Follow‐Up of a Patient with Mandibular Complete‐Arch Fixed Implant‐Supported Prosthesis on 4 Implants: A Clinical Report

Mandibular complete‐arch fixed implant‐supported prostheses are recognized as one of the earliest and most popular prostheses in implant dentistry. This prosthesis was the main focus in the early era of osseointegration. Despite its widespread popularity, few clinical reports have described long‐term follow‐up greater than 10 years for this type of prosthesis. This report describes a 30‐year follow‐up of a patient who underwent treatment for a mandibular complete‐arch fixed implant‐supported prosthesis with 4 machined surfaced implants, opposing a maxillary complete denture. This report documents a variety of photographs and radiographs taken over a period of 30 years to compare bone levels at various stages of care and maintenance, including de novo bone formation underneath the distal cantilevers due to functional loading. The biologic and biomechanical response to this treatment protocol and long‐term clinical observations and prosthodontic outcome and maintenance needs are also addressed.     

Occlusal force pattern during mastication in dentitions with mandibular fixed partial dentures supported on osseointegrated implants

The occlusal force pattern during chewing and biting was studied in eight edentulous patients whose dentitions had been restored with mandibular bilateral posterior two-unit cantilever fixed prostheses supported on osseointegrated titanium fixtures and occluding with complete maxillary dentures. The chewing pattern was comparable to that reported for subjects with complete healthy dentitions or with tooth-supported cross-arch fixed partial dentures. However, during chewing and swallowing the voluntary capacity of the jaw-closing muscles was used to a much greater extent. Contrary to reports for cantilevers in tooth-supported cross-arch unilateral posterior two-unit cantilever fixed partial dentures occluding with natural teeth, the posterior cantilever segments in the present fixture-supported cantilever prostheses occluding with complete dentures regularly exhibited the largest local forces. Despite this, material failures of this type of fixed prostheses are rare, as demonstrated in long-term follow-up studies.     

种植体与天然牙联合修复牙列缺损86例临床分析

目的:评价种植体与天然牙联合修复牙列缺损的效果.方法:86例患者缺牙隙均为牙槽骨中度以上吸收以及(或)下牙槽神经管位置相对偏高,或上颌窦过低(管嵴距、窦崤距<10mm).种植101颗国产两段式纯钛种植体,3～6个月后采用天然牙与种植体联合方法修复.结果:修复后观察2～3a,有效率达93.4%.结论:单纯采用种植体修复受到解剖结构限制时,采用种植体与天然牙联合修复不失为一种简便、有效的方法.     

Influence of occlusal contacts of implant on adjacent teeth and antagonists displacements

This study examined the optimum occlusal contacts of implant prostheses to maintain good oral condition after treatment. Three subjects who had two contiguously missing teeth (first and second molars) were selected. The displacement path of the implant, the adjacent tooth and the antagonistic tooth during clenching were measured using the type M-3 three-dimensional tooth displacement transducer. The occlusal contacts of implant prostheses changed according to the following four conditions. A contact: the inner inclination of the upper buccal cusp, B contact: the inner inclination of the upper lingual cusp, C contact: the outer inclination of the upper lingual cusp, and ABC contact: including the above three contacts. The measurements were performed at least six months after implant surgery. In each subject, the implants and the adjacent teeth were not affected by the change of the occlusal contact of the implant prosthesis, but the opposing teeth were affected. In the case of implantation in the lower side, the opposing tooth displaced in the buccal direction with A contact and C contact, which was a different direction to that of the natural tooth. The antagonist with B contact displaced in the lingual direction, which was the same direction as that of the natural tooth. The antagonist with ABC contact displaced in the lingual or buccal direction. It is concluded that the occlusal adjustment of implants needs much care: in the case of only A contact or C contact, non-physiological distortion might occur in periodontal tissues of the opposing teeth of the implant.     

Dental crowding in primary dentition and its relationship to arch and crown dimensions among preschool children of Davangere

The purpose of the present study was to evaluate dental crowding in the deciduous dentition and its relationship to the crown and the arch dimensions among preschool children of Davangere. Stratified randomized selection of one hundred, 3-4 year old healthy children with all primary teeth erupted was done and divided into two groups. One group had children with anterior crowding in both the arches while the other had spacing. Alginate impressions of the upper and lower arches were made and the study casts were obtained. The tooth and arch dimensions were determined. Mesiodistal dimensions of all the teeth were significantly larger in the crowded arch group. However, the buccolingual dimensions of the maxillary right central incisor, mandibular lateral incisors and the maxillary molars and the crown shape ratio of maxillary lateral incisors, mandibular canines and mandibular right second molar was statistically different. No significant correlation was found between the arch width and the presence of crowding of deciduous dentition. The arch depth of the spaced dentition was greater when compared to the crowded ones. The arch perimeter of the crowded arches was significantly less than the spaced arches.     

Is a Fixed Hybrid Prosthesis with Distal Cantilever Appropriate for Maxillofacial Defects? A Report of Two Patients

The most important objectives in restoring the maxillofacial patient are the restoration of function and psychological improvement through esthetics. Acquired maxillary and mandibular defects due to significant trauma or surgery represent a major challenge for the clinician and patient. Dental implant‐retained prostheses represent a well‐documented and reliable treatment option and can also help patients with maxillofacial defects by eliminating denture instability and improving function. Full‐arch fixed dental hybrid prostheses provide functional and psychological advantages and also reduce the load on vulnerable soft and hard tissues in the reconstruction area. Two clinical reports are presented describing the prosthetic rehabilitation using dental implant‐supported fixed hybrid prostheses with clinical and radiographic follow‐up of 3 years.     

A restorative-orthodontic treatment approach in the older patient

This report presents a case requiring a combination of restorative dentistry and orthodontic treatment in a mature adult patient. Occlusal splint and periodontal therapies were used initially. Orthodontic treatment combined the use of the occlusal splint and fixed appliance in the maxillary arch. Sectional fixed appliances were used in the mandibular arch. The final restorations were fixed--movable bridges in the mandibular arch and a removable tooth and mucosally borne prosthesis in the maxilla. Retention of the orthodontic result was provided by the fixed prostheses in the lower arch and the continued wear of a full coverage maxillary occlusal splint at night served to prevent relapse of the upper teeth.