Single mandibular implant study (SMIS) − masticatory performance − results from a randomized clinical trial using two different loading protocols

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.

Single lateral implant for mandibular overdentures as a fallback solution or a viable treatment alternative: Four case reports

This report of four clinical cases aims to illustrate the use of a lateral implant as a solution for implant overdentures in the mandible in different clinical situations. The first two cases describe the clinical situations of patients wearing two-implant mandibular overdentures until the failure of one of the implants, one due to implant loss and the other due to a fracture of an abutment screw, and how the conditions were managed. The third case illustrates the placement of a single implant to retain an overdenture, where a midline implant, as originally planned, was not feasible due to anatomic reasons. The final case describes the use of a lateral implant to support and retain a single-implant mandibular overdenture. The four cases demonstrate that a single lateral implant can be utilized as sole retention in cases of a failing contra-lateral implant and as an alternative to a single implant in the midline.

Treatment effect of implant-supported fixed complete dentures and implant overdentures on patient-reported outcomes: A systematic review and meta-analysis

OBJECTIVES

To analyze the effect of implant treatment in edentulous patients rehabilitated with implant-supported fixed complete dentures (IFCDs) or implant overdentures (IODs) on dental patient-reported outcomes (dPROs).

MATERIALS AND METHODS

In January 2022, Medline, Embase, CINAHL, Cochrane Library, PubMed Central, Web of Science, and ClinicalTrials.gov were screened for prospective clinical studies on completely edentulous patients treated with IFCDs and/or IODs, reporting pre-treatment and follow-up dPROs. Hedges' g effect sizes (ES) with corresponding 95% confidence intervals (CI) were calculated. Afterward, meta-analyses were conducted using random effect models.

RESULTS

A total number of 1608 records was initially identified. Of those, 28 studies reporting dPROs from 1457 patients were finally included. The applied dental patient-reported outcome measures (dPROMs) included several versions of the Oral Health Impact Profile (OHIP) or specific items assessing satisfaction with Visual Analogue Scales (VAS). The overall ES was large for rehabilitation with IFCDs (1.68 [CI: 1.15, 2.20]) and IODs (1.26 [CI: 0.99, 1.52]) with no significant difference (p = .165) between the two. Denture stability was the only factor rated significantly higher for IFCDs (ES difference: 2.37 [CI: 0.21, 4.54]; p = .032). Subgroup analyses revealed moderately higher ES for IODs on two implants relative to one implant (ES difference: 0.73 [CI: 0.34, 1.12]; p < .001).

CONCLUSIONS

There is a strong positive effect of implant treatment in edentulous patients, independent of the type of prosthetic rehabilitation. In patients seeking high stability, IFCDs may be preferable. In mandibular IODs on a single implant, there was a significantly positive effect of an additional implant on dPROs.

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.

Prosthodontic outcomes of mandibular overdenture treatment with one or two implants: 4-year results of a randomized clinical trial

OBJECTIVE

To assess the incidence of prosthodontic maintenance events and complications during 4 years of follow-up after mandibular overdenture treatment with one or two implants.

METHODS

Participants received one or two implants inserted in the midline (1-IOD group) or the lateral incisor-canine area bilaterally (2-IOD group). Implants were loaded with an early loading protocol after 3 weeks. Programmed recall visits were scheduled at the 6-, 12-, 36-, and 48-month follow-ups and nonprogrammed visits in case of prosthodontic complaints. The type of maintenance was registered, and the final treatment outcome was classified as successful, surviving, unknown, dead, repair, or retreatment.

RESULTS

Forty-seven participants, mean age 65.4 ± 8.6, 74.5% female, were included (1-IOD = 23; 2-IOD = 24) and 44 completed the 4-year follow-up. A total of 159 prosthodontic maintenance events occurred and 89 in unscheduled visits. The most common event was the need for minor modifications of the denture base due to sore spots in the oral mucosa (n = 56 in 31 patients), matrix activation (n = 54 in 34 patients), and overdenture fracture (n = 25 in 18 patients). A "successful" or "surviving" outcome could be attributed to 57.5% of cases, whereas 38.3% needed repair. No significant differences in the incidence of prosthodontic events or treatment outcomes were found between the two groups.

CONCLUSIONS

Findings show that 1-IODs perform similar to 2-IODs when considering the incidence of fractures and the need for prosthodontic maintenance, including adjustments of the overdenture and the attachment system.

Single mandibular implant study - chewing efficiency - 5-year results from a randomized clinical trial using two different implant loading protocols

PURPOSE

To investigate the chewing efficiency of edentulous patients wearing complete dentures, treated with a single implant in the mandible, placed underneath the existing mandibular dentures, using two different loading protocols (immediate loading or conventional loading), over an observation period of 5 years.

METHODS

One-hundred and fifty-eight (158) edentulous seniors aged 60-89 years received an implant in the midline of the lower jaw and were randomized either to the immediate loaded group A (n=81) or the conventional loaded group B (n=77). Chewing efficiency was obtained before treatment, one month after implant placement during the submerged healing phase (only group B) and 1, 4, 12, 24 and 60 months after implant loading.

RESULTS

After 5 years, chewing tests from 89 patients (45 in the immediate loading group and 44 in the conventional loading group) were available for every recall visit and thus statistically analyzed. The chewing efficiency increased over time in both groups. A significant increase was observed up to 4 months after loading (p≤0.05). Later, chewing efficiency further increased, but not significantly. Between the two loading protocols, chewing efficiency did not differ significantly (p>0.05) at any follow-up investigation.

CONCLUSION

A single mandibular implant placed underneath existing mandibular dentures improves chewing efficiency of edentulous patients significantly over an observation period of 5 years, irrespective of the loading protocol.

Masticatory Ability for a Single Implant Mandibular Overdenture Retained by Two Different Attachments: A Randomized Controlled Trial

Objective

The aim of this randomized clinical trial was to compare the masticatory ability subjectively between ball and Cendres+Métaux Locator (CM-LOC) attachment for a single implant retained mandibular overdenture throughout a 24-month follow-up period.

Materials and Methods

Eighty completely edentulous patients were recruited. All patients received new complete dentures, and masticatory ability was recorded using a questionnaire (baseline record). All patients received a single implant in the midline of the completely edentulous mandible. After 3-month healing period, patients were randomized using sealed envelopes into two groups: ball or CM-LOC attachment. The same masticatory ability questionnaire was used to record masticatory ability for both groups after 2 weeks of pickup and 3-, 6-, 9-, 12-, and 24-month follow-up. Comparison between the study groups was done using Mann–Whitney U test for independent samples. Two-sided P values less than 0.05 were considered statistically significant.

Results

The mean masticatory scores improved for both attachments, with no statistically significant difference between them throughout the 24-month follow-up. The CM-LOC attachment group showed a greater improvement change in masticatory ability after 6- and 12-month follow-up (−12.47 ± 12.006, −11.46 ± 14.625; P=0.826), while the ball attachment group showed a slight improvement after the 24-month follow-up (−11.72 ± 12.368, −10.88 ± 11.963; P=0.778).

Conclusion

Single implant retained mandibular overdenture improved masticatory ability subjectively with no significant difference between both attachments used although the ball attachment showed better masticatory ability scores after 24-month follow-up.

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.

Masticatory performances and maximum occlusal forces of immediate and conventional loaded two-implant supported overdentures retained by magnetic attachments: preliminary study of randomized controlled clinical trial

Background

The appropriate loading protocol to improve masticatory performance (MP) is still unclear in elderly patients and two-implant overdentures (2-IODs) wearers. This study aimed to compare the long-term MP and maximum occlusal force of immediate loading (IL) and conventional loading (CL) of 2-IODs retained by magnetic attachments. Nineteen edentulous patients were randomly assigned to either an IL (n=10) or CL group (n = 9). In the IL group, the implant was loaded on the same day as insertion, whereas it was loaded 3 months after insertion in the CL group. Magnetic attachments were used to retain all overdentures to the implants. MP, measured by a piece of color-changeable chewing gum and a gummy jelly test, and maximum occlusal force, measured using an occlusal force measuring device, were assessed in both groups at baseline and at 3-, 4-, and 5-year follow-ups.

Results

No significant differences were observed in the MP and the maximum occlusal force between the IL and CL groups at any time point. However, a significantly higher MP was observed at the 3-year time point in the IL group (P = 0.036). The maximum occlusal force revealed a significant correlation with MP, both with the color-changeable chewing gum and gummy jelly at 5 years.

Conclusion

After long-term observation, no significant differences in MP and maximum occlusal force were observed between the IL and CL groups. However, compared to pre-implant insertion of the complete denture, the MP in the IL group significantly improved at 3 years. Furthermore, the maximum occlusal force was significantly correlated with MP at 5 years.

Trial registration

UMIN, UMIN000009889. Registered on 28 January 2013.

Evaluation of biofilm colonization on multi-part dental implants in a rat model

Background

Peri-implant mucositis and peri-implantitis are highly prevalent biofilm-associated diseases affecting the tissues surrounding dental implants. As antibiotic treatment is ineffective to fully cure biofilm mediated infections, antimicrobial modifications of implants to reduce or prevent bacterial colonization are called for. Preclinical in vivo evaluation of the functionality of new or modified implant materials concerning bacterial colonization and peri-implant health is needed to allow progress in this research field. For this purpose reliable animal models are needed.

Methods

Custom made endosseous dental implants were installed in female Sprague Dawley rats following a newly established three-step implantation procedure. After healing of the bone and soft tissue, the animals were assigned to two groups. Group A received a continuous antibiotic treatment for 7 weeks, while group B was repeatedly orally inoculated with human-derived strains of Streptococcus oralis, Fusobacterium nucleatum and Porphyromonas gingivalis for six weeks, followed by 1 week without inoculation. At the end of the experiment, implantation sites were clinically assessed and biofilm colonization was quantified via confocal laser scanning microscopy. Biofilm samples were tested for presence of the administered bacteria via PCR analysis.

Results

The inner part of the custom made implant screw could be identified as a site of reliable biofilm formation in vivo. S. oralis and F. nucleatum were detectable only in the biofilm samples from group B animals. P. gingivalis was not detectable in samples from either group. Quantification of the biofilm volume on the implant material revealed no statistically significant differences between the treatment groups. Clinical inspection of implants in group B animals showed signs of mild to moderate peri-implant mucositis (4 out of 6) whereas the mucosa of group A animals appeared healthy (8/8). The difference in the mucosa health status between the treatment groups was statistically significant (p = 0.015).

Conclusions

We developed a new rodent model for the preclinical evaluation of dental implant materials with a special focus on the early biofilm colonization including human-derived oral bacteria. Reliable biofilm quantification on the implant surface and the symptoms of peri-implant mucositis of the bacterially inoculated animals will serve as a readout for experimental evaluation of biofilm-reducing modifications of implant materials.

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.

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.

Do implant-retained mandibular overdentures maintain radiographic, functional, and patient-centered outcomes after 3 years of loading?

OBJECTIVES

Analyzing whether radiographic, functional, and oral health-related quality of life (OHRQoL) outcomes are maintained over 3 years of implant-retained mandibular overdenture (IMO) function and investigating the bite force associations in the 3rd year of function.

MATERIAL AND METHODS

A longitudinal clinical study in which 24 IMO users were evaluated during a 3-year follow-up period. Patients' posterior area index, masticatory function, OHRQoL and bite force were assessed. The masticatory function parameter ST_X50 reflects the opening through which 50% of the crushed particles would pass, ST_B describes the homogeneity of the bolus, and the masticatory efficiency parameters ME_5.6 and ME_2.8 represent the % of material retained in the 5.6 and 2.8 mm sieves, respectively.

RESULTS

A significant increase in posterior area index (p ≤ .01) was found in all evaluated periods. Minor deteriorations in ST_X50 (p ≤ .01) and ME_5.6 (p ≤ .01) between the 2nd and the 3rd year coincided with improvements in ST_B (p ≤ .01), number of cycles (p ≤ .01), and cycle time (p = .02). The global OHIP-Edent score (p = .02) and the scores in the functional limitation (p = .02), psychological discomfort (p ≤ .01), and handicap domains (p ≤ .01) increased significantly between the 2nd and the 3rd year. Correlations between bite force and cycle time (p = .03) and between posterior area index and ST_X50 (p ≤ .01) and ME_2.8 (p = .02) were also found.

CONCLUSION

Changes in posterior area index, masticatory function, and OHRQoL are still ongoing during the 3rd year of IMO function. Bite force and posterior area index influence the masticatory function outcomes in the 3rd year of IMO function.

Immediate versus delayed loading of strategic mini-implants under existing removable partial dentures: patient satisfaction in a multi-center randomized clinical trial

OBJECTIVE

The purpose of this study was to evaluate and compare the effects of the immediate and delayed loading of strategic mini-implants (MIs) on the satisfaction of patients with removable partial dentures (RPDs).

MATERIALS AND METHODS

In this multi-center randomized clinical trial, strategic MIs were inserted under 79 RPDs in 76 participants. Two questionnaires, one for the upper jaw and one for the lower jaw, were given before surgical intervention and 2 weeks, 4 months, 4.5 months, 1 year, 2 years, and 3 years after implant insertion. To estimate the loading effect (immediate vs. delayed) in terms of the odds ratio, an ordinal logistic regression model was used. The Wilcoxon matched-pairs signed-rank test, which was corrected for clusters in the patient population, was used to evaluate changes in patient satisfaction.

RESULTS

After 4 months, a statistically significant difference in favor of the immediate loading group was recognized in terms of the overall satisfaction score. The patient satisfaction scores recorded after 4.5 months and 1, 2, and 3 years showed substantial improvements compared with the scores recorded before implant insertion in both groups. At the item level, substantial improvements were noted in the following domains: general satisfaction, RPD retention, stability, support, eating, speaking, and aesthetics.

CONCLUSIONS

Strategic MIs improved the satisfaction of patients with RPDs during the medium-term follow-up period. An earlier improvement in the satisfaction of patients with RPDs was seen after immediate loading of the MIs as compared with delayed loading.

CLINICAL RELEVANCE

Inserting MIs under existing RPDs can improve patients' satisfaction with their RPDs in several domains.

The influence of habitual consumption of chewing gums in the outcome of masticatory performance tests using two-coloured chewing gums

The aim of this study is to assess the influence of regular consumption of chewing-gums on the Masticatory Performance (MP); and to determine if increasing the consumption improves the MP of non-regular consumers. We recorded the chewing-gums consumption rate (CGC) and measured the MP of 265 participants (µ = 47.09, σ = 22.49 years) using the Variance of the Histogram of the Hue (VhH) image processing method. Then, participants were instructed to increase the consumption, and the MP was measured again (SESSION) two and four days after. Normality of MP was verified with Kolmogorov-Smirnov and Shapiro-Wilk tests. The association between the age and the consumption rate was measured with GEE and the eta-squared statistic. Finally, a 3 × 3 mixed ANOVA with SESSION as the within-subject factor and CGC as the between-subjects factor was run. Session-wise and group-wise comparison were performed with post hoc Bonferroni. No systematic error was detected for VhH (p = 1.00). Kolmogorov-Smirnov and Shapiro-Wilk tests confirmed the normality of the distribution of MP (p > 0.05). There was a significant effect of SESSION on MP, F(1.746, 457.328) = 59.075, p < 0.001; furthermore, there were significant differences in MP between SESSIONs. Additionally, there was a significant effect of CGC on MP, with F (2, 356.53) = 564.73, p < 0.001. In conclusion, the chewing-gum consumption habits influence the two-coloured chewing gum mixing test. The apparent MP of non-regular consumers can be improved by prescribing a controlled increase in the consumption of chewing-gums for a few days.

Dental Patient-Reported Outcome Measures Are Essential for Evidence-Based Prosthetic Dentistry

For evidence-based dental treatment decision-making in prosthetic dentistry, evidence from scientific studies performed in the appropriate population with state-of-the-art interventions, reasonable controls, and relevant outcomes is required. This article will briefly review patient populations involved and interventions applied in prosthetic dentistry and more extensively review outcomes used for evidence-based dental treatment decision-making in prosthetic dentistry. Dental patient populations in prosthetic dentistry usually suffer from extensive loss of tooth substance and/or tooth loss. Typical interventions in prosthetic dentistry are replacement of a substantial amount of tooth structure and lost teeth with conventional or implant-supported fixed or removable dental protheses. Sufficient controls or comparisons should also involve no treatment for tooth loss as a legitimate option. For many years, prosthodontic treatment almost solely focused on disease-oriented outcomes such as numerical replacement of missing teeth to restore current oral health and prevent further deterioration, and now, dental patient-reported outcomes (dPROs), the outcomes that are directly reported by the patient, are gaining increasing attention. dPROs are what matters most for the patient, and dPRO measures have several advantages when applied in clinical practice and research settings compared with traditional disease-oriented measures such as ease of applicability and less burdensome for the clinicians. In evidence-based prosthetic dentistry, there should be a shift to fewer applied dPRO measures, with only one instrument becoming standard. Furthermore, dPROs will probably also become tools to assess patients' oral health status in clinical practice in a standardized manner. Finally, information on dPROs will become an integral part of evidence-based treatment decision-making in prosthetic dentistry.

The patient general satisfaction of mandibular single-implant overdentures and conventional complete dentures: Study protocol for a randomized crossover trial

BACKGROUND

Mandibular overdentures retained by a single implant placed in the midline of edentulous mandible have been reported to be more comfortable and function better than complete dentures. Although single-implant overdentures are still more costly than conventional complete dentures, there are a few studies which investigated whether mandibular single-implant overdentures are superior to complete dentures when patient general satisfaction is compared. The aim of this study is to assess patient general satisfaction with mandibular single-implant overdentures and complete dentures.

METHODS

This study is a randomized crossover trial to compare mandibular single-implant overdentures and complete dentures in edentulous individuals. Participant recruitment is ongoing at the time of this submission. Twenty-two participants will be recruited. New mandibular complete dentures will be fabricated. A single implant will be placed in the midline of the edentulous mandible. The mucosal surface of the complete denture around the implant will be relieved for 3 months. The participants will then be randomly allocated into 2 groups according to the order of the interventions; group 1 will receive single-implant overdentures first and will wear them for 2 months, followed by complete dentures for 2 months. Group 2 will receive the same treatments in a reverse order. After experiencing the 2 interventions, the participants will choose one of the mandibular prostheses, and yearly follow-up visits are planned for 5 years. The primary outcome of this trial is patient ratings of general satisfaction on 100 mm visual analog scales. Assessments of the prostheses and oral health-related quality of life will also be recorded as patient-reported outcomes. The secondary outcomes are cost and time for treatment. Masticatory efficiency and cognitive capacity will also be recorded. Furthermore, qualitative research will be performed to investigate the factors associated with success of these mandibular denture types. Clinical outcomes, such as implant survival rate, marginal bone loss, and prosthodontic complications, will also be recorded.

DISCUSSION

The results of this randomized crossover trial will clarify whether mandibular single implants and overdentures for edentulous individuals provide better patient general satisfaction when compared to conventional complete dentures.

TRIAL REGISTRATION

This clinical trial was registered at the University Hospital Medical Information Network (UMIN) Center (UMIN000017883).