Masticatory function and bite force of mandibular single-implant overdentures and complete dentures: a randomized crossover control study

Changes in masticatory performance and bite force after treatment with mandibular overdentures retained by four titanium-zirconium mini implants: One-year randomised clinical trial

OBJECTIVE

This prospective study is part of a randomised clinical trial and reports the changes in masticatory performance (MP) and bite force, and explores their influential factors, 1 year after the provision of mandibular overdentures retained by four titanium-zirconium mini implants.

METHODS

Edentulous patients received conventional complete dentures, followed by placement of four mini implants (Straumann® Mini Implant System) in the anterior mandible and converting the conventional prosthesis into a mandibular overdenture. Treatment protocols were randomised using a 2×2 factorial design combining different surgical (flapped vs. flapless) and loading (immediate vs. delayed) protocols. MP was assessed using a two-colour mixing ability test and a colorimetric analysis to measure the level of colour mixing (Variance of Hue-VoH). Maximum voluntary bite force (MBF) was measured by a digital gnathodynamometer in the posterior and anterior regions. Sex, age, surgical and loading protocols and ridge morphology were tested as independent variables. MP and MBF tests were performed at baseline (pre-treatment) and the 3-, 6- and 12-month after implant loading. Descriptive statistics, independent t-test, and linear mixed-effect model (LMM) regression were used for data analysis.

RESULTS

Seventy-four participants were assessed and 73 completed the 1-year follow-up. Statistically significant improvements in functional parameters were observed in all follow-up periods compared to baseline (p < .001). The flapless protocol was associated with higher improvement in MP at the 3-month follow-up (p = .004), while less resorbed ridges were associated with better MP (p = .038) and higher MBF (p < .001).

CONCLUSION

The mandibular overdenture protocol using four titanium-zirconium mini implants was effective in improving MP and MBF of edentulous patients, compared to pre-treatment values. The findings also suggest that improvements in chewing function and bite force are impacted by clinical factors since better outcomes were observed for flapless surgeries and less resorbed edentulous ridges.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.Gov ID NCT04760457.

Mandibular overdenture with a single implant in the canine region (c-SIMO): a feasibility study

OBJECTIVES

The aim of this multi-center pilot study was to assess the viability and feasibility of a novel treatment concept - the canine-positioned single implant mandibular overdenture (c-SIMO), with the single implant placed on the patient's preferred chewing side instead of the midline.

MATERIALS AND METHODS

Participants received a single implant in the canine region of their preferred chewing side, based on an Asymmetry Index observed during mastication. The pre-existing mandibular denture was transformed into a c-SIMO on a spherical attachment. The primary outcome was oral health-related quality of life (OHRQoL), measured with GOHAI and OHIP-EDENT. Secondary outcomes included denture satisfaction index (DSI), chewing efficiency (CE), maximum bite force (MBF), implant survival and success, and prosthetic maintenance. Data analysis included descriptive statistics and bivariate comparison tests.

RESULTS

Fifteen participants received the c-SIMO treatment (mean age: 69.9 ± 7.0). Implant success and survival rates were 100% at 1 year. Patient-reported outcome measures improved significantly compared to pre-treatment values (OHIP-EDENT: p = 0.001; DSI: p = 0.001; GOHAI: p = 0.002). Masticatory outcomes also improved significantly (CE: p = 0.001; overall MBF: p = 0.005). Post-implant, MBF was significantly higher in the ipsilateral side compared to the contralateral side at 2 weeks (p = 0.019) and 3 months (p = 0.015), but no longer at T3 (p = 0.730). Common prosthodontic events included denture base adjustments (n = 17) and matrix activation (n = 9).

CONCLUSIONS

This pilot study concludes that c-SIMO is a promising treatment option, and a potential alternative to the single midline implant overdenture.

CLINICAL RELEVANCE

The novel treatment concept of a canine-positioned single implant mandibular overdenture could be a viable treatment alternative to the midline positioning.

The effect of single-implant overdentures on cognitive function in older adults: A 3-year follow-up report

OBJECTIVE

To investigate the occurrence of mild cognitive impairment in edentulous patients up to 3 years after they received single-implant overdentures (1-IODs).

METHODS

This was a follow-up study for a crossover randomized controlled trial comparing 1-IODs and conventional complete dentures, with patient satisfaction as the primary outcome. In the present study, the cognitive function of the patients, measured with the Japanese version of the Montreal cognitive assessment (MoCA-J), was evaluated as the secondary outcome at baseline and 2 months, 1 year, 2 years, and 3 years after 1-IOD placement. The total and domain (memory, executive function, visuospatial skills, language, attention, and orientation) MoCA-J scores of the patients at each timepoint were analyzed and compared.

RESULTS

Twenty-two patients with edentulous mandibles received 1-IODs. Within-group comparisons revealed that the total MoCA-J scores at 1 year and 3 years after 1-IOD placement were significantly increased compared with baseline scores. Additionally, the memory domain scores at all timepoint were significantly increased compared with the baseline scores, and the executive function domain scores at the 2-month, 2-year and 3-year timepoint were significantly increased compared with the baseline scores.

CONCLUSION

Patients with edentulous mandibles who underwent 1-IOD placement showed significantly improved total scores of MoCA-J after 1 year and 3 years of wearing 1-IODs. In addition, they showed significantly improved memory domain scores at 2 months, 1 year, 2 years, and 3 years after 1-IOD placement and executive function domain scores at 2 months, 2 years, and 3 years after 1-IOD placement.

CLINICAL SIGNIFICANCE

The results of this study suggest that 1-IOD treatment for older adults, especially those with edentulous mandibles, may prevent cognitive decline regardless of the condition of the maxilla.

The Single Midline Implant in the Edentulous Mandible-Current Status of Clinical Trials

The single midline implant in the edentulous mandible is a treatment concept that has often been controversially discussed. Nearly 30 years ago, the first available clinical results revealed high implant survival rates and remarkable improvements in oral comfort, function, patient satisfaction and oral health-related quality of life for edentulous patients compared to the situation with no implant. However, the clinical trials were predominantly conducted with a small number of patients over a short to medium follow-up period. Today, numerous clinical investigations on the single midline implant in the edentulous mandible, which increasingly include longer-term observation periods, are available. It is the aim of this overview to present the current literature and to highlight the clinical problems. This article is a 2023 update of a review published by the authors in the German language in 2021 in the German journal Implantologie. In total, 19 prospective clinical trials with a follow-up period of 0.5-10 years were analyzed. Over this observation period, single implants with modern rough implant surfaces in the edentulous mandible reveal high implant survival rates of between 90.9 and 100% when a conventional delayed loading protocol was applied.

Oral function of implant-assisted removable partial dentures with magnetic attachments using short implants: A prospective study

OBJECTIVES

This prospective study aimed to compare the oral functions of removable partial dentures (RPDs) with those of implant-assisted removable partial dentures (IARPDs) with short implants and magnetic attachments in patients with mandibular Kennedy class I and II.

MATERIAL AND METHODS

Thirty participants with mandibular Kennedy class I or II and at least three distal missing teeth were recruited. Oral functions, including mixing ability, comminuting ability, maximum bite force, and occlusal contact area, were assessed for RPDs (stage 0), IARPDs with healing caps (stage 1), and IARPDs with magnetic attachments (stage 2). The implants were loaded with occlusal force in stages 1 and 2. Finally, the data of the 27 participants who completed the evaluation at stage 2 were analyzed. The Wilcoxon signed-rank test with Bonferroni correction was used to assess the differences in the oral functions among the different stages.

RESULTS

The implant survival rate was 93.8%. There were significant differences in the comminuting ability and occlusal contact area between stages 0 and 2 (p < .001 and p = .036, respectively) and stages 1 and 2 (p = .003 and p = .015, respectively). Regarding the maximum bite force, there was a significant difference between stages 1 and 2 (p = .018). However, there was no significant difference in the mixing ability between the three stages.

CONCLUSIONS

Within the limitations of this study, it was concluded that IARPDs in the mandible with short implants and magnetic attachments may improve oral functions.

Comparison of general satisfaction, oral health-related quality of life, and patient's self-assessment between mandibular single-implant overdentures and experimental removable complete dentures: A randomized crossover clinical trial

Objective Patient satisfaction with single-implant overdentures (1-IODs) is unclear. This randomized crossover trial aimed to compare the general satisfaction, oral health-related quality of life, and patients' self-assessment between mandibular 1-IODs and experimental removable complete dentures (eRCDs). Methods New mandibular RCDs were fabricated for 22 patients with edentulous mandibles. After adapting to the RCDs, one implant was inserted in the mandibular midline. The participants were then randomly classified into groups 1 and 2. Group 1 received IODs for the first 2 months, while group 2 used eRCDs with a non-loaded implant in the midline. After 2 months, the treatment was switched. Four validated, patient-reported dental outcome measures were assessed: general satisfaction, Japanese version of the Oral Health Impact Profile for edentulous subjects (OHIP EDENT-J), General Oral Health Assessment Index (GOHAI), and Patient's Denture Assessment (PDA). The assessments were performed at the end of the IOD- and eRCD- use periods. Results General satisfaction was significantly higher during the IOD period (p = 0.002). Significant differences were observed in all domains of the OHIP, except orofacial pain (p = 0.084). Further, the total score (p<0.001) and the scores of the physical (p<0.001) and psychosocial functioning (p = 0.001) domains of the GOHAI differed significantly. The total PDA score (p = 0.001) and the scores of the function (p = 0.004), lower denture (p = 0.002), esthetics and speech (p = 0.026), and importance (p = 0.009) domains were significantly higher during the IOD period than during the eRCD period. Conclusion General satisfaction, oral health-related quality of life, and patient self-assessment scores were significantly higher for 1-IODs than for eRCDs. Clinical significance Within the limitations of this study, we found that mandibular single-implant overdentures may be an efficient alternative to mandibular experimental removable complete dentures due to higher general satisfaction, oral health-related quality of life, and patient self-assessment scores of dentures.

Speech and the swallowing threshold in single implant overdenture wearers: A paired control study

BACKGROUND

Single implant mandibular overdentures (SIMOs) can improve mastication in edentulous elderly people. However, little attention has been paid to their effects on articulation disorders and the swallowing threshold relative to those of conventional complete dentures (CDs).

OBJECTIVE

To compare the effects of new conventional CD set and SIMOs on articulation disorders, mandibular movements during speech and swallowing threshold using a paired study design.

METHODS

Twenty-two edentulous Brazilian Portuguese-speaking elderly people (mean age 66.7 ± 4.6 years) were first evaluated whilst wearing their old conventional CDs. Articulation disorders were analysed by audio and video recordings, mandibular movements during speech were measured by kinesiography, and the swallowing threshold was assessed by masticatory cycle counting and medium particle size (X₅₀ ) calculation. Participants then received new conventional CDs, and evaluations were repeated 2 months later. Subsequently, single implants were installed in the midlines of subjects' mandibles, and the conventional CDs were converted to SIMOs. After 2 months of SIMOs use, the evaluations were repeated. Data were submitted to the Cochran-Mantel-Haenszel and ANOVA.

RESULTS

No difference in articulation disorders was found between new conventional CD and SIMO use. The frequency of anterior lisp during /s/ and /z/ phoneme pronunciation was reduced with new conventional CD use relative to old conventional CD use (p < .05). The X₅₀ decreased progressively with new conventional CD and SIMO use (both p < .05).

CONCLUSION

SIMOs do not alter speech relative to new well-fitted conventional CDs, but improved the swallowing threshold, in edentulous elderly people.

'Differences in self-perceived OHRQoL between fully dentate subjects and edentulous patients depending on their prosthesis type, socio-demographic profile, and clinical features'

OBJECTIVES

This observational cross-sectional study aimed to evaluate and compare the oral health-related quality of life (OHRQoL) and clinical performance between dentate subjects and edentulous patients restored with conventional dentures or implant overdentures.

METHODS

85 edentulous patients were grouped as follows: Group-1 (CD): conventional denture wearers (n= 42), and Group-2 (IO): implant-retained overdenture wearers (n= 43). For the OHRQoL comparisons, a control group of subjects with a healthy natural dentition (Group-3, ND; n= 50) was included. Participants completed three validated questionnaires (OHIP-14sp, OHIP-20sp, and QoLIP-10). Socio-demographic data, prosthesis-related factors, clinical condition of the mouth, and patient subjective evaluations, were gathered. Descriptive and non-parametric probes were run (α= 0.05).

RESULTS

The ND group was the most unsatisfied (OHIP-14sp; p≤ 0.001). The OHIP-20sp attributed significantly worse Psychological disability (p= 0.029) and Handicap (p= 0.027) to CD wearers when compared to IO wearers. The CD group showed the significantly highest need for relining (p= 0.041), and the lowest retention (p= 0.011). The OHIP-14sp disclosed a significantly worse OHRQoL for those volunteers who had a job (p= 0.003), a basic education instead of a secondary one (p= 0.022), and no partner (p= 0.006).

CONCLUSIONS

The overall OHRQoL was comparable for both prosthodontic groups, being modulated by socio-demographic and prosthesis-related features. Nonetheless, CD wearers presented prosthetic complications more frequently.

Single implant overdenture reinforced with a metallic framework: A 2-year clinical follow-up

INTRODUCTION

To prevent single-implant overdenture (SIO) fracture, the inclusion of a framework in the overdenture has been suggested. However, no investigations verified their benefits.

OBJECTIVE

To evaluate prosthetic maintenance events, patient satisfaction, and mastication of SIO reinforced by metallic framework users.

MATERIAL AND METHODS

Fifteen volunteers had a new set of complete dentures converted into an SIO containing a framework. Maintenance events were recorded, while patient satisfaction was assessed using a visual analog scale. Masticatory performance (MP) was evaluated using the sieving method, maximum bite force (MBF) by pressure sensors, and masseter thickness by ultrasound. Measurements were performed 2, 12, and 24 months after SIO use. Repeated-measures ANOVA and paired Student's t-tests (p < 0.05) were applied.

RESULTS

Matrix exchange was the most prevalent maintenance event (83.6%), and no SIO was fractured during the entire follow-up. Satisfaction with the SIO stability decreased (p < 0.01) after 12 months. MP did not change between evaluations (p > 0.05). Conversely, MBF and masseter thickness improved after 12 and 24 months of SIO use (p < 0.05).

CONCLUSIONS

Reinforced SIO did not fracture during 2 years but requires maintenance. It improves bite force and muscle thickness, maintaining MP values. Satisfaction with SIO stability decreased in the first year of use.

Single versus two-implant mandibular overdentures using early-loaded titanium-zirconium implants with hydrophilic surface and ball attachments: 1-year randomized clinical trial

OBJECTIVE

This randomized clinical trial aimed to compare the outcomes of the mandibular overdenture retained by one (1-IOD) or two (2-IOD) implants.

MATERIALS AND METHODS

Participants received new complete dentures, were assessed at baseline and randomly assigned to groups. Early loaded single midline implant (1-IOD) or two implants in the canine regions bilaterally (2-IOD). Ball attachments were used for overdenture retention. Post-treatment outcomes (6- and 12-month follow-ups) included patient satisfaction, oral health-related quality of life measures, and chewing function. Data analysis included within- and between-group comparisons, and Generalized Estimating Equations. Both superiority and non-inferiority hypotheses were tested.

RESULTS

Forty-seven participants were included (1-IOD = 23; 2-IOD = 24). Significant improvements in OHIP-Edent were observed after insertion of new dentures and at the 1-year follow-up compared with baseline. No differences were found between the 1- and 2-IOD groups for the OHIP-Edent and QoLFAST scores. Patient satisfaction with the mandibular denture improved significantly from baseline to the 6-month follow-up and remained unaltered until 1 year, with no differences between groups. The magnitudes of treatment effect sizes were moderate to large for patient-reported outcomes. Progressive improvement in chewing function occurred in both groups. Non-inferiority testing based on a 15% non-inferiority margin showed inconclusive results for patient-reported outcomes, whilst chewing function in the 1-IOD group was concluded to be not inferior to the 2-IOD group.

CONCLUSIONS

Results support the use of both 1- and 2-IOD. The 1-IOD was also an acceptable alternative to the 2-IOD as a secondary option for the treatment of the edentulous mandible.

Effects of rehabilitation with complete dentures on bite force and electromyography of jaw and neck muscles and the correlation with occlusal vertical dimension

OBJECTIVES

The purpose of this study was to assess the effects of oral rehabilitation with complete dentures on bite force and electromyography of the suprahyoid and sternocleidomastoid muscles, and their correlation with occlusal vertical dimension (OVD). The research questions were "What are the effects of rehabilitation with complete dentures on bite force and electromyography of suprahyoid and sternocleidomastoid muscles, and how are they correlated with OVD?"

MATERIALS AND METHODS

Patients who are wearers of unsatisfactory removable complete dentures were attended in three sessions (T0, T1, and T2). At T0, while the patients still wore the old dentures, they were submitted to bite force and surface electromyographic exams of the suprahyoid and sternocleidomastoid muscles. These exams were repeated, and the OVD was measured while the patients wore their old and new prostheses, 30 days after insertion of the new prosthesis (T1). The exams were repeated 100 days after the insertion of the new prosthesis (T2). The data were submitted to the Shapiro-Wilk normality test, analysis of variance (ANOVA), and Pearson correlation and linear regression, all with 5% significance.

RESULTS

Fifteen patients participated in the study. No statistically significant difference was observed for bite force or electromyography in T0, T1, or T2. However, the correlation and regression tests showed important interactions between the OVD and maximum voluntary occlusal bite force, as well as the OVD and electromyography during deglutition for the suprahyoid muscles.

CONCLUSION

Rehabilitation did not impact bite force nor the activity of the assessed muscles (electromyography). On the other hand, OVD was shown to be an important factor for bite force, and deglutition of water after rehabilitation.

CLINICAL RELEVANCE

This study shows what are the influences of rehabilitation on oral functions and reinforces the importance of corrected reestablishment of OVD because it has been found to be an important factor for bite force and electromyography during deglutition.

Patient-reported outcome measures of edentulous patients restored with single-implant mandibular overdentures: A systematic review

AIM

To review the literatures concerning the effect of the single-implant mandibular overdenture (SIMO) on patient-reported outcome measures (PROMs) and masticatory function in the fully edentulous patients.

MATERIALS AND METHODS

Electronic databases (PubMed, Cochrane Library, EMBASE and Web of Science) were searched, complemented with manual resources. Prospective studies published in English up to February 2020 reporting the effect of SIMO on PROMs and masticatory function in the edentulous patients were included. This review focused on oral health-related quality of life (OHRQoL), satisfaction and masticatory function outcomes.

RESULTS

Of 1157 initially screened articles, 9 randomised controlled trials (RCTs) and 8 prospective studies involving 551 subjects fulfilled the inclusion criteria. Two RCTs were graded as high risk of bias or some concern, while others were low risk. All prospective studies had adequate representativeness and assessment, but only one study had a controlled cohort. In general, the edentulous patients restored with SIMOs had improved OHRQoL and general satisfaction compared to those with conventional complete dentures (CCDs), but the outcome of masticatory function was controversial. Compared with two-implant mandibular overdenture (TIMO), SIMO showed no significant differences regarding general satisfaction and satisfaction with speech, comfort, chewing ability, aesthetics and social life. Conflicting results were observed in OHRQoL and satisfaction with retention and stability. Better masticatory performance was observed in TIMO group than SIMO group.

CONCLUSION

Within the limitation of this review, SIMO is featured with better OHRQoL and satisfaction than CCD. SIMO and TIMO rendered similar patient satisfaction, but TIMO had better masticatory performance.

Masticatory function improvement with the use of mandibular single-implant overdentures in edentulous subjects: a systematic literature review

INTRODUCTION

In this systematic review, several masticatory function parameters assessed during mandibular single-implant overdenture (SIO) use were compared to pre- SIO placement values in edentulous patients with aim of contributing to a consensus regarding denture treatment options.

EVIDENCE ACQUISITION

This study was registered a priori in the PROSPERO database (CRD42018106567). Two independent reviewers carried out electronic searches in eight databases, without language or time frame limitations, to collate clinical studies comparing masticatory function of edentulous patients before versus after SIO installation with the implant placed on the mandibular midline. Risk of bias was assessed with a before-and-after tool and evidence certainty level was evaluated with the Grading of Recommendations Assessment, Development and Evaluation program.

EVIDENCE SYNTHESIS

Eleven studies were included in this review (1 prospective, 3 crossover trials, 4 randomized clinical trials, 2 paired clinical trials, and 1 pilot). Enrolled patients were mostly over 60 years old; all patients were using conventional complete dentures (CD) prior to SIO installation. Masticatory performance, masticatory efficiency, bite force, and muscle activity were improved after the SIO placement compared to during mandibular CD use. Mandibular movement and masticatory ability data were inconclusive. Most of the studies had low risk of bias, but all had very low certainly level ratings due to methodological heterogeneity.

CONCLUSIONS

Placement of SIO improves masticatory function, as reflected mostly by masticatory performance and efficiency data, relative to CD use. Further studies comparing dental rehabilitation options, including SIOs, are needed to improve the quality of evidence in the literature.