Masticatory function and patient satisfaction with implant-supported mandibular overdentures: a prospective 5-year study

PURPOSE: The aim of this study was to assess the outcome of treatment with implant-supported mandibular overdentures in terms of biting and chewing, in entirely satisfied and not fully satisfied patients. MATERIALS AND METHODS: Twelve edentulous patients who had worn dentures for at least 5 years participated. They were in good health but had retention problems with their mandibular dentures. First, all patients received new dentures. After 3 months, two Astra Tech implants were placed in the anterior part of the mandible, and 6 months later the abutments were connected. Patient assessment (questionnaire) and functional recordings (chewing ability, bite force, electromyographic activity) were performed with the new dentures, and again 3 months, 1 year, and 5 years after overdenture treatment. RESULTS: After treatment, all patients were able to comminute hard and tough food, the maximum bite force and the chewing activity increased in parallel, and the duration of the chewing cycle was reduced. Every patient felt improved function and reduction of chewing pain. However, the seven patients not fully satisfied with the function of the implant-supported mandibular overdentures were characterized by lower muscle activity, even before implant placement, than the entirely satisfied patients. CONCLUSION: Implant-supported mandibular overdenture treatment permits better biting and chewing function than conventional complete dentures.     

Oral function in subjects with overdentures supported by osseointegrated implants

Nine subjects treated with overdentures on osseointegrated implants in the mandible were functionally evaluated before and after treatment. The last recordings were performed 1 yr after treatment. The evaluation comprised a subjective and a clinical examination. Measurements of bite force and of chewing efficiency were also performed. The bite force was measured during gentle biting, biting as when chewing and biting with maximal effort. Almonds were used as test food. All subjects improved subjectively as well as clinically after treatment. The bite force during gentle biting increased on average from 17.3 N before treatment to 24.0 N 1 yr after treatment. A corresponding improvement of biting as when chewing was also found, from on average 24.0 N before to 38.7 N after treatment. The maximal bite force increased from on average 74.6 N at the baseline examination to 131.5 N at the 1-yr follow-up. The chewing efficiency improved from Ci = 4 (Median value) before treatment to Ci = 2.8 (Median value) after treatment. It is concluded that treatment with an overdenture supported by osseointegrated implants in the mandible improves oral function compared to the situation before treatment.     

Oral function in subjects with overdentures supported by osseointegrated implants

Abstract – Nine subjects treated with overdentures on osseointegrated implants in the mandible were functionally evaluated before and after treatment. The last recordings were performed 1 yr after treatment. The evaluation comprised a subjective and a clinical examination. Measurements of bite force and of chewing efficiency were also performed. The bite force was measured during gentle biting, biting as when chewing and biting with maximal effort. Almonds, were used as test food. All subjects improved subjectively as well as clinically after treatment. The bite force during gentle biting increased on average from 17.3 N before treatment to 24.0 N 1 yr after treatment. A corresponding improvement of biting as when chewing was also found, from on average 24.0 N before to 38.7 N after treatment. The maximal bite force increased from on average 74.6 N at the baseline examination to 131.5 N at the 1-yr follow-up. The chewing efficiency improved from C_i=4 (Median value) before treatment to C_i=2.8 (Median value) after treatment. It is concluded that treatment with an overdenture supported by osseointegrated implants in the mandible improves oral function compared to the situation before treatment.     

Long-term effects on chewing with mandibular fixed prostheses on osseointegrated implants

Twenty-seven edentulous patients with denture adaptation problems were first given optimal conventional complete dentures and then a fixed prosthesis on osseointegrated dental implants in the lower jaw (and a complete maxillary denture). Masticatory function was evaluated by means of a questionnaire, a comminution test for chewing efficiency, and bite force measurements on four occasions: with the original (I) and optimal complete dentures (II) and 2 months (III) and 3 years (IV) after insertion of the fixed mandibular prosthesis on implants. No significant improvement of masticatory function was found after conventional denture treatment. After insertion of the fixed mandibular implant bridge, a marked improvement of the patients' assessment of their chewing ability and of the results of the chewing efficiency test and the bite force measurements was recorded. The test results were further improved after the 3-year observation period, which indicates that adaptation to the new prosthetic situation is a gradual process.     

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.     

Improving masticatory performance,bite force,nutritional state and patient's satisfaction with implant overdentures: a systematic review of the literature

Oral function with removable dentures is improved when dental implants are used for support. A variety of methods is used to measure change in masticatory performance, bite force, patient's satisfaction and nutritional state. A systematic review describing the outcome of the various methods to assess patients' appreciation has not been reported. The objective is to systematically review the literature on the possible methods to measure change in masticatory performance, bite force, patient's satisfaction and nutritional state of patients with removable dentures and to describe the outcome of these. Medline, Embase and The Cochrane Central Register of Controlled Trials were searched (last search July 1, 2014). The search was completed by hand to identify eligible studies. Two reviewers independently assessed the articles. Articles should be written in English. Study design should be prospective. The outcome should be any assessment of function/satisfaction before and at least 1 year after treatment. Study population should consist of fully edentulous subjects. Treatment should be placement of any kind of root‐form implant(s) to support a mandibular and/or maxillary overdenture. Fifty‐three of 920 found articles fulfilled the inclusion criteria. A variety of methods was used to measure oral function; mostly follow‐up was 1 year. Most studies included mandibular overdentures, three studies included maxillary overdentures. Implant‐supported dentures were accompanied by high patient's satisfaction with regard to denture comfort, but this high satisfaction was not always accompanied by improvement in general quality of life (QoL) and/or health‐related QoL. Bite force improved, masseter thickness increased and muscle activity in rest decreased. Patients could chew better and eat more tough foods. No changes were seen in dietary intake, BMI and blood markers. Improvements reported after 1 year apparently decreased slightly with time, at least on the long run. Treating complete denture wearers with implants to support their denture improves their chewing efficiency, increases maximum bite force and clearly improves satisfaction. The effect on QoL is uncertain, and there is no effect on nutritional state.     

Chewing ability in patients restored with cross-arch fixed partial dentures

The chewing ability of subjects with cross-arch fixed partial dentures was compared with that of subjects with complete healthy dentitions and complete-denture wearers. Chewing ability was expressed in terms of the number of chewing strokes, chewing time, chewing efficiency, and chewing performance. Almonds were used as the test food. In terms of chewing efficiency, that is, comminution in relation to time, subjects with cross-arch fixed partial dentures exhibited a chewing ability inferior to that of subjects with complete healthy dentition but superior to that of complete denture wearers. However, in terms of chewing performance, which describes the degree of pulverization before the time of swallow, chewing ability in subjects with cross-arch fixed partial dentures was almost as good as in subjects with complete, healthy dentitions and superior to that of complete denture wearers.     

The effect of denture stability on bite force and muscular effort

This study tested the hypothesis that denture instability limits the amount of voluntary muscular effort generated by denture wearers. Seventeen edentulous subjects (seven men, 10 women; mean age 60·3 ± 13·0 years) with newly acquired implant-retained mandibular overdentures and a conventional maxillary denture participated. Maximum bite forces and corresponding electromyographic (EMG) activity from the temporalis and masseter muscles (bilaterally) were recorded under two experimental conditions: (i) Unilateral premolar and molar bites without additional support, and (ii) premolar and molar bites with bite block support on the opposite side. In addition, EMG values alone were recorded during maximum clenching without any transducer between the upper and lower dentures. The level of muscular effort was significantly higher with greater denture support. These results indicate that denture instability probably prevents denture wearers from using the full potential of their jaw muscles, especially during unilateral biting and chewing, even with two implants supporting the mandibular dentures.     

Comparison of patient satisfaction,quality of life,and bite force between elderly edentulous patients wearing mandibular two implant‐supported overdentures and conventional complete dentures after 4 years

This study compared two groups of patients who were elderly and edentulous, one group included subjects who had mandibular overdentures supported by two implants (Group I); the other groups wore conventional complete dentures (Group II). This retrospective study included 100 edentulous patients (50 from each group) with an average age of 67.86 years, who had been followed for 4 years. The groups were compared in terms of patient satisfaction, quality of life (QOL), and bite force. The bite force and patient satisfaction scores of Group I were found to be statistically significantly higher than Group II (p < .05). However, no statistically significant difference was found between the two groups’ QOL scores (p > .05) except on the physical pain subscale (p = .013). Based on these results, it can be concluded that after 4 years of function, subjects wearing mandibular overdentures supported by two implants had higher values for bite force and patient satisfaction scores, but similar QOL scores when compared to conventional complete denture‐wearers.     

Masseter muscle thickness, chewing efficiency and bite force in edentulous patients with fixed and removable implant-supported prostheses: a cross-sectional multicenter study

Objectives: Edentulous patients may be restored with conventional dentures (C/C), implant‐supported overdentures (IOD) or implant‐supported fixed dental prostheses (IFDP). Null‐hypotheses: chewing efficiency, maximum voluntary bite force (MBF) and masseter muscle thickness (MMT) are lower in patients with C/IOD compared with the patients with bimaxillary IFDPs. Both groups perform better than C/C and are inferior to fully dentate controls. Material and methods: Ethical approval was obtained. For this multicenter cross‐sectional study, 80 patients were recruited. Four groups of different dental states comprised of either implant‐supported prostheses (C/IOD and IFDP/IFDP) or served as control‐groups (C/C and fully dentate D/D). Chewing efficiency was assessed with a two‐colour mixing ability test. MBF was measured bilaterally with a force gauge. Two dimensional ultrasonography was used to measure MMT bilaterally. Results: Chewing efficiency in C/IOD and IFDP/IFDP (difference NS) was better than in C/C, but not as good as in D/D. MBF in C/IOD was lower than in IFDP/IFDP. Chewing efficiency and MBF were significantly lower in IFDP/IFDP, who had experienced chipping or fracture of the prosthetic superstructure. Median MMT of patients with implant‐supported prostheses was between those with C/C and fully dentate participants. There was no significant difference in MMT between C/IOD and IFDP/IFDP. Conclusion: Supporting complete prostheses with oral implants seems to have positive effects on the thickness of the masseter muscle, maximum bite force as well as chewing efficiency. The type of implant‐supported prostheses may have an influence on the magnitude of the effect. To cite this article :
Müller F, Hernandez M, Grütter L, Aracil‐Kessler L, Weingart D, Schimmel M. Masseter muscle thickness, chewing efficiency and bite force in edentulous patients with fixed and removable implant‐supported prostheses: a cross‐sectional multicenter study.
Clin. Oral Impl. Res. 23 , 2012; 144–150.
doi: 10.1111/j.1600‐0501.2011.02213.x     

Patient satisfaction and preference with magnet, bar-clip, and ball-socket retained mandibular implant overdentures: a cross-over clinical trial

PURPOSE: The purposes of this study were to: (1) determine patient satisfaction with implant-supported mandibular overdentures using magnet, bar-clip, and ball-socket attachments; and (2) assess the relation between maximum bite force and patient satisfaction. MATERIALS AND METHODS: In a cross-over clinical trial, 18 edentulous patients with mandibular denture complaints received two mandibular implants and new mandibular and maxillary dentures. The mandibular denture was initially without any kind of attachment system, but it was fitted with one of the attachment types after 3 months. The attachments were changed 3 months thereafter, in random order. A questionnaire on denture complaints was administered at baseline (with the old denture), after 3 months of function with the new denture without attachments, and after 3 months of function with each of the attachments (within-subject comparison). In addition, patients were asked to express their overall appreciation of their dentures on a VAS. Patients' preferences were determined at the end of the experiment. Maximum bite forces were obtained from a previous study with the same population. Five scales of denture complaints were constructed. Mean scale and VAS scores at the five evaluation points were compared among the groups. Pearson correlation was calculated between maximum bite force and scale and VAS scores. RESULTS AND CONCLUSION: Mandibular implant-supported overdenture treatment reduced various denture complaints. The VAS score better reflected patients' preferences than did scale score. Patients strongly preferred bar-clip (10/18 subjects) and ball-socket attachments (7/18 subjects) over magnet attachments (1/18 subjects). Patients' preferences could not be predicted on the basis of baseline observations. Maximum bite force was not correlated to scale or VAS score. Hence, patients with higher maximum bite forces were not necessarily more satisfied.     

Bite force and oral function in complete denture wearers

Oral function was evaluated in complete denture wearers by using a questionnaire, clinical examination and bite force measurements. Ten patients with satisifactory and ten with unsatisfactory dentures were studied and six of the latter patients were reexamined 1 year after the insertion of new dentures. The bite force values were compared with those obtained in ten dentate controls. No significant differences in bite force were found between the satisfactory and unsatisfactory denture groups. Individual values varied much in both groups. The six patients re-examined were satisfied with their new dentures and thought they had improved chewing but no significant increase of bite force was found. The maximal bite force was 5-6 times greater in the dentate subjects than in the denture wearers. Edentulous persons are very handicapped in masticatory function and even clinically satisfactory complete dentures are poor substitutes for natural teeth.     

覆盖义齿和全口义齿咀嚼功能的比较研究

目的：对比研究全口覆盖义齿和全口义齿的咀嚼功能。方法：选择13例全口覆盖义齿修复患者，14例全口义齿修复患者，测试咀嚼杏仁和小枣时的咀嚼效率，记录下颌运动轨迹；记录左右侧嚼肌，颞肌前束，颞肌后束在息止颌位，大力咬合和咀嚼小枣和杏仁时的肌电图。结果：覆盖义齿组咀嚼杏仁和小枣的效率显著高于常规总义齿组，下颌运动轨迹的规则性和末端集中性优于常规总义齿组，咀嚼运动中，覆盖义齿组颞肌前后束的肌电活动显著强于常规总义齿组，且肌电活动中提颌肌群的协同作用更加明显，结论：全口覆盖义齿对无牙颌患者咀嚼功能的恢复显著优于全口义齿，是一种良好的修复方式。     

Pain and instability during biting with mandibular implant-retained overdentures

We tested in a randomized controlled clinical trial the effect of pain and instability of dentures on bite force with different degrees of mucosal support. The trial involved 3 groups who had received: 1) a new conventional denture (CD-group), 2) an implant-mucosa-borne overdenture on 2 IMZ implants (IMZ-group) or 3) a mainly implant-borne overdenture retained by a transmandibular implant (TMI-group). Fifty-three women and 15 men, mean age 59 years, participated in this study. Bite force measurements were made unilaterally with a transducer and bilaterally with a bite fork. After the measurements, subjects were asked whether or not biting had caused pain or tilting of one of the dentures. Significantly more complete-denture wearers reported pain. They reported more frequent pain in the mandible than in the maxilla (P < 0.001), whereas implant-groups seemed to experience more often pain in the maxilla. On the transducer, maxillary dentures of the CD-group tilted less (P < 0.01) and mandibular dentures more (P < 0.05) compared to the implant-groups. With the bite fork, tilting occurred more often in the incisal-cuspid area than in the molar region (P < 0.001). No effect of pain and tilting was observed on maximum bite force. It appears that oral implants used to stabilize mandibular dentures permit subjects to exert higher bite forces and reduce the pain as otherwise felt in the mandible during maximum biting. Due to this stabilization, pain and instability of the maxillary denture can become the limiting factor for a further increase in bite force.     

Two-implant mandibular overdentures: simple to fabricate and easy to wear

Success rates for titanium dental implants in the anterior mandible are very high. Because of these success rates, as well as lower costs, it is common to treat edentulous patients with just 2 implants and ball anchors for retention of the overdenture, instead of 4 implants and a bar. In this paper the fabrication of 2-implant overdentures is described. In a controlled clinical trial (to be reported elsewhere), 30 subjects received a 2-implant overdenture for the mandible and a conventional prosthesis for the maxilla. The 30 control patients received conventional complete dentures for both jaws. The stability of the overdentures was excellent, and the lingual dimensions of the denture could be reduced to the level of the mylohyoid line to provide more space for the tongue. In patients with tense labial musculature or a limited amount of attached gingiva, it was important to elevate the shoulder of the implant and ball abutment above the gingival level to avoid peri-implant problems. Significantly fewer visits for adjustment related to post-placement pressure spots were required for mandibular overdentures than for conventional mandibular prostheses.     

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.     

Relationship between oral function and occlusal support in denture wearers

Patients with removable partial dentures or complete dentures do not demonstrate masticatory function to the same level as patients with a full set of natural teeth. The purpose of this study was to characterize the relationship between reduction of masticatory function, in terms of masticatory performance and bite force, and the existence of remaining natural occlusal supports as assessed by the Eichner index. One hundred and eighteen removable partial denture and complete denture wearers were selected for analyses. These subjects were divided into four groups depending upon the number of occlusal supports. Seventy dentate subjects with full occlusal support were designated as a comparison group. Bilateral bite force was measured at the first molar region in all subjects. Masticatory performance was assessed using the modified Masticatory Performance Index. Peanuts were used as the test food. Both bite force and masticatory performance were significantly associated with group classification. Moreover, both bite force and masticatory performance of the four denture groups were significantly reduced compared to the comparison group and this tendency was remarkable for the denture groups without occlusal support. These results suggest that the existence of functional tooth units may be a key factor in preservation of masticatory function.     

The influence of maximum bite force on patient satisfaction and quality of life of patients wearing mandibular implant overdentures

The treatment of edentulism with traditional complete dentures can often induce impaired masticatory function due to limited retention and stability, especially in the lower jaw. Mandibular interforaminal implants have been widely used to stabilize the dentures, consequently improving masticatory performance in edentulous individuals. The aim of the present study was to document the influence of this improved masticatory function on patient satisfaction and quality of life of patients wearing mandibular implant-supported overdentures. Sixty-two patients treated with various types of implant-supported mandibular overdentures between 2004 and 2007 were included in this retrospective study. Maximum bite force (MBF) was measured bilaterally using a device with 2 strain gauges connected to a strain gauge measurement system. All the included patients were asked to fill out visual analog scale (VAS) forms based on general and chewing satisfaction and OHIP-14 forms. Results were analyzed by the Spearman rho test. No statistically significant correlation was found between MBF values and VAS general or VAS chewing satisfaction or Oral Health Impact Profile scores (P > .05). The results indicate that MBF is not associated with the satisfaction or quality of life of implant-supported mandibular overdenture wearers.     

Changes in bite force and chewing efficiency after denture treatment in edentulous patients with denture adaptation difficulties

Masticatory function was studied by means of a chewing efficiency test and bite forces measurements in forty-nine edentulous patients who had applied for treatment with fixed protheses on osseointegrated dental implants. Registrations were performed with the original complete dentures and after treatment aiming at optimizing the dentures. The patients were divided into two groups and the post-treatment recordings were completed after adaptation periods of 2 and 6 months, respectively. The functional tests showed mainly small and non-significant changes after the denture treatment. Improvement was greater, however, in those with the poorest pre-treatment values. Chewing efficiency deteriorated after treatment in the older patients (more than 50 years) while it did not change in the younger ones. A longer adaptation period did not lead to better functional results. The findings are discussed in relation to the fact that the patients were waiting for implant treatment, with consequent psychological implications for interpretation.     

Implant anchored complete mandibular denture: evaluation of masticatory efficiency, oral function and degree of satisfaction

Masticatory efficiency, oral function and degree of satisfaction with the treatment received were analysed in a group of fully edentulous patients with severe atrophy of the mandibular bone, rehabilitated with complete removable dentures, before and after anchoring the dentures to osseointegrated implants. Masticatory efficiency increased significantly and chewing cycles increased in amplitude after anchoring the denture. The component of the chewing cycle that most influenced the increase in functional area was the lateral one. A correlation was found between the increase in the lateral component of the chewing cycle and the increased masticatory efficiency achieved with implant‐anchored dentures. The degree of satisfaction with their rehabilitation reported by the subjects was correlated neither to increased masticatory efficiency nor to improved oral function.