Implant survival in 1- versus 2-implant mandibular overdentures: a systematic review and meta-analysis

Single mandibular midline-implant supported overdentures: Fifteen-year clinical outcome

OBJECTIVE

The aim of this prospective pilot study was to evaluate the 15-year clinical performance of mandibular overdentures supported by a single midline implant in edentulous patients.

METHODS

Eleven eligible patients were enrolled. A single implant was inserted in the midline of the mandible (Root Line; Promote, Camlog Biotechnologies, diameter 3.8 mm, length 11-13 mm). In 6 patients, a non-submerged protocol with moderate immediate loading on healing abutments was applied. The submerged healing protocol was followed in the other five patients with uncovering taking place two months after insertion. The denture bases were relined temporarily with a soft acrylic temporary relining material during the healing period. Ball-attachments and corresponding matrixes were provided two months after insertion. The baseline data were collected on the day of implant connection. Follow-up examinations were conducted four weeks after loading and then annually. Required prosthodontic maintenance interventions were recorded and conducted.

RESULTS

Six patients died during the fifteen-year observation period; their data were evaluated up to the last clinical recall. The mean observation time was 139 months. No implant loss has been recorded, amounting up to a survival rate of 100 %. The most frequent maintenance intervention was readjustment of the retention, which was performed multiple times for some patients.

CONCLUSIONS

The concept of mandibular overdentures supported by one single midline implant in edentulous patients seems to be a valid treatment option, especially for patients that cannot afford the costs of two or more implants or cannot undergo extensive surgery. Periodic recall-appointments are recommended due to the frequent interventions required.

CLINICAL SIGNIFICANCE

The use of a single midline implant to support mandibular overdentures in edentulous patients appears to be a viable treatment option, particularly for those who cannot afford multiple implants or undergo extensive surgery.

Tailoring magnesium-doped coatings for improving surface and biological properties of titanium-based dental implants

Physicochemical modifications of biomaterials have been proposed to overcome bone integration impairment and microbial infections. The magnesium (Mg) incorporation on dental implant surfaces has shown positive results in bone-to-implant contact and in the reduction of microbial colonization. Here, we explored the potential of using different Mg precursors to synthesize coatings via plasma electrolytic oxidation (PEO) on commercially pure titanium (cpTi), aiming to optimize the surface and biological properties. For this, we investigated Mg acetate and Mg nitrate precursors in different concentrations (0.04 M and 0.12 M), using calcium (Ca) and phosphorus (P) as the base electrolyte for all groups. Coatings with only the CaP base electrolyte were used as the control group. The surfaces were characterized by confocal laser scanning microscopy, scanning electron microscopy, film thickness measurement, profilometry, wettability, X-ray diffraction, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, electrochemical behavior, and ion release. For biological analyses, the adhesion (2 h) of Streptococcus sanguinis was evaluated, as well as MC3T3-E1 osteoblastic cells proliferation at 1 and 3 days, and mineralization of calcium phosphates after 28 days. PEO treatment using different Mg precursors promoted physicochemical modifications of cpTi. The experimental groups MgN 0.04 and MgN 0.12 exhibited higher surface roughness and wettability compared to the other surfaces. Regardless of the Mg precursor, the higher the ion concentration in the electrolyte solution, the higher the Mg atomic concentration on the surfaces. Concerning the electrochemical behavior, the results indicated that the incorporation of Mg in the coatings may enhance the electrochemical performance. Mg treated surfaces did not promote greater bacterial adherence when compared to the control. MgAc 0.04 and MgAc 0.12 coatings displayed improved MC3T3-E1 pre-osteoblastic cells proliferation at day 3 compared to other groups. The hydroxyapatite formation on MgAc 0.12 surfaces was higher than in the other groups. Our data indicate that Mg precursor selection positively influences physicochemical and biological properties of coatings. Specifically, MgAc 0.12 surfaces showed the most promising surface features with greater cell proliferation, without affecting microbial colonization, being an excellent candidate for surface treatment of titanium-based dental implants.

Comparative evaluation of pattern and distribution of stresses in single- and double-implant overdenture using ball-ring, positioner, and magnet-keeper attachment under different loading conditions: A finite element analysis

AIM

The aim is to evaluate and compare stress distribution characteristics of ball, magnet, and positioned attachment systems in single and double implant-retained overdentures using the finite element method (FEM).

SETTING AND DESIGN

In vitro (in silico study) finite element analysis (FEA).

MATERIALS AND METHODS

A Styrofoam mandible with duplicated silicon mucosa was used to construct a mandibular complete denture. Implants of size 12 mm by 3.4 mm body diameter (Implantium, Dentium, Korea) were used along with ball O-ring, positioner, and magnet attachment system for constructing single and double implant overdenture. FEA models were processed defining geometry. Six models were formulated, namely, three models of central single implant and three for double implant overdenture using ball O-ring attachment, positioner attachment, and magnet attachment named B1, P1, M1, B2, P2, and M2, respectively. The FEM analysis was done using ANSYS workbench 16.0. A load of around 100N was applied bilaterally in the first molar regions, anteriorly between the two central incisors, and unilaterally on the right first molar region. Stresses were calculated according to the Von Mises stresses scale. Stress magnitude and patterns were analyzed and interpreted accordingly.

STATISTICAL ANALYSIS USED

Stress patterns and maximum principal stress were described.

RESULTS

FEM analysis revealed that stress concentration in the B1 model was the highest. Anterior loading produced maximum stress followed by unilateral and lastly bilateral loading. In the bone, stress concentration was the highest in the crestal bone region (3-18 MPa). Mucosa showed the least amount of stress in all models (1.3-3 MPa). Stress patterns in dentures were symmetric with concentration on the mid-lingual and molar premolar area (3-18 MPa). Implants showed stress concentration near the collar and the internal connection region (7.5-24 MPa). Maximum stresses were around the head of prosthetic abutments (10.5-24 MPa). The stress concentration in the ball head was typically located in the abutment neck. In positioner attachment, stress was located in the inner open end area (11-20.1 MPa). For the keeper, stresses were at its base and stress patterns extended into the body (10.5-17.7 MPa). Less stress magnitude was seen for all models on bilateral loading (10.5-15 MPa).

CONCLUSION

Magnet and positioner attachments have a more favorable stress distribution in both single and double implant-retained overdentures. Bilateral loading conditions are more favorable for uniform stress patterns.

Single versus two dental implants retained mandibular over dentures: comparison of function, patient satisfaction, oral health-related quality of life and success of treatment

OBJECTIVE

To compare the effectiveness of prosthetic rehabilitation of edentulous patients using conventional complete dentures (CD), single median dental implant retained over dentures (SIMOD) with over dentures retained by two dental implants (TIMOD).

METHODS

Thirty completely edentulous patients (fifteen each arm) presented to the Faculty of Dental Sciences, University of Peradeniya were randomly selected for the SIMOD or TIMOD groups. Patients were initially provided with CD. Surgical implant placement and prosthetic procedures were conducted at the Faculty of Dental Sciences. Osseointergration was confirmed, healing caps and then ball attachments were fixed on the implants. Clinical outcome was assessed by clinician, patient, and oral health related quality of life (OHRQOL) using OHIP-14 scale. Data were analyzed using Minitab P < 0.05 was considered as statistically significant level.

RESULTS

Patient comfort, esthetics, chewing, speech, general satisfaction, denture retention, stability, and support with TIMOD & SIMOD had been significantly increased than CD (p < 0.05) at 3, 6 months, and 1 year review. OHIP-14 scale showed statistically significant improved oral health related quality of life with SIMOD and TIMOD compared to CD.

CONCLUSION

SIMOD & TIMOD have improved outcome assessed by the patient and clinician and OHRQOL of the individual than CD. SIMOD can also be considered for successful management of completely edentulous patients.

Minimally invasive approaches for implant-supported overdentures in the atrophied mandible

OBJECTIVES

The study compares three minimally invasive approaches for the retention of implant supported mandibular complete dentures, particularly focusing on patient satisfaction.

BACKGROUND

The McGill Consensus Statement recommends restoration of the edentulous mandible with an overdenture retained on two implants. Alternatively, less invasive treatment concepts with shorter treatment times have been developed for critical cases.

MATERIAL AND METHODS

Thirty-nine patients (with a total of 78 implants) with advanced mandibular bone atrophy were randomly assigned to three groups: "single standard implant-retained overdentures" (SSO) and "mini-implant-retained overdentures" (MO), which was further subdivided into "two mini-implant-retained overdentures" (TMO) and "four mini-implant-retained overdentures" (FMO). The technical and biological parameters and oral health-related quality of life were evaluated over a 10-year period. Data were analysed for group comparisons and longitudinal trend analysis.

RESULTS

Sixteen patients (42%) dropped out during the study period. At the time of follow-up, 98.4% of the implants were in situ. The first need for technical intervention occurred after 3.8 ± 1.1, 4.2 ± 0.9, and 4.6 ± 1.3 years in the TMO, SSO, and FMO groups, respectively. Attachment exchange (39%) was the most frequently performed intervention in all groups. Healthy peri-implant and mucosal conditions were observed in 74% and 40% of patients after 1 and 10 years, respectively. The OHIP-G14 score was 22.6 before implantation, 7.6 at 1 year (effect size [ES]: 1.1), and 5.4 at 10 years (ES: 2.3).

CONCLUSION

Irrespective of the minimal concept selected, complete mandibular dentures retained on implants improved the subjective perception of the quality of life. Application of these alternative minimal concepts may be practical in clinical practice.

Oral health self-perception, maximum bite force and masticatory efficiency in patients with overdentures with different attachment systems-A crossover study

BACKGROUND

The literature is unclear about how the different attachment systems for overdentures impact the maximum bite force, the masticatory efficiency and how this impact in the oral health self-perception in patients.

OBJECTIVE

To evaluate the effect of two attachment systems (O-ring and Locator) for mandibular overdenture using single implant on quality of life, maximum bite force (BF) and masticatory efficiency (ME).

METHODS

Twenty-eight completely edentulous denture wearers with a mandibular symphysis implant were randomly selected and allocated into two groups in a crossover study, considering O-ring and Locator attachment types. The quality of life and self-perception of oral health were assessed using the Oral Health Impact Profile (OHIP-Edent) and Geriatric Index of Determination of Oral Health (GOHAI) questionnaires, respectively. BF was measured using a gnathodynamometer and ME by chewing silicone cubes and almonds in different numbers of cycles.

RESULTS

There was no difference between the attachment systems about self-perceived oral health and impact on quality of life (p > .05). The O-ring-type system obtained a significantly higher BF than the locator-type system (p = .04). Regardless of the food chewed, no statistically significant difference was observed with the type of attachment (p > .05). The ME was directly proportional to the masticatory cycles only for almonds (p < .01).

CONCLUSIONS

Locator and O-ring inserts had a similar impact on patients' quality of life, self-perception of oral health and ME. Additionally, the O-ring system exhibited superior properties in the BF.

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.

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.

Effects of multisensory environment/stimulation therapy on adults with cognitive impairment and/or special needs: A systematic review and meta-analysis

AIM

This review aimed to evaluate the effects of multisensory environments/stimulation (MSE/MSS) therapy, on the behavior and psychological symptoms in adults with cognitive impairment and/or special needs.

METHODS

Online database searches were performed to identify studies reporting on the effects of MSS/MSE therapy in adults (>18 years). Data were extracted for the following investigated outcomes including anxiety, depression, mood, behavioral attributes, biomedical parameters, cognition, motor skills, quality of life (QoL), pain, and end of life quality. Two reciprocally blinded investigators extracted the data. Inter-investigator reliability (𝝹) was calculated. A meta-analysis and a qualitative analysis were performed on the information extracted.

RESULTS

Thirty-six studies were included for data extraction and analysis. Meta-analysis of the included studies revealed a significant improvement with the MSE/MSS therapy, for agitation (p = .018), anxiety (p = .023), cognition (p < .001), and depression (p < .001). MSS/MSE therapy demonstrated a tendency for the improvement of the QoL in adults (p = .05).

CONCLUSION

MSE/MSS therapies are beneficial in cognitively impaired adults and improve their anxiety, depression, cognitive and other behavioral attributes such as agitative behaviors. Promoting these therapies in geriatric care may help to improve/reduce the challenging/care-resistant behaviors in adults and facilitate effective provision of the necessary care.

Single Implant-Retained Mandibular Overdentures: A Literature Review

The absence of teeth, known as edentulism, poses considerable obstacles in prosthodontic care and greatly affects a person's well-being. Conventional complete dentures frequently lead to problems like instability and insufficient retention, especially in the lower jaw. Fortunately, the introduction of dental implants has transformed the way we approach edentulous patients, as they now offer support and enhanced retention for removable prostheses, thus revolutionizing their treatment. While a consensus exists on using two implants for retaining mandibular overdentures, the associated cost may be prohibitive for economically disadvantaged individuals. As a solution, the concept of single implant-retained mandibular overdentures has emerged, catering to individuals with limited financial resources and complete tooth loss. This review explores the efficacy and suitability of the single implant overdenture approach, along with an overview of treatment options for edentulous patients, including traditional dentures, tooth-supported overdentures, and implant-supported overdentures. The preservation of bone, improvements in functional abilities, and psychological benefits associated with overdentures are discussed. Moreover, various classifications and prosthetic options for implant overdentures, specifically for mandibular cases, are presented. This literature review aims to provide a comprehensive understanding of possible treatment options and focus on the single implant-retained mandibular overdenture approach and its implications in prosthodontic rehabilitation for edentulous patients.

Single-Implant Overdentures Retained by a Novel Attachment: A Mixed Methods Crossover Randomized Clinical Trial

INTRODUCTION

Single-implant mandibular overdentures (SIMOs) are one of the least invasive implant treatments for edentulism. The new Novaloc attachment system can improve the clinical performance of implant-retained overdentures but has not been tested for SIMOs.

OBJECTIVES

To compare Novaloc and a gold standard system (Locator) for SIMOs in an edentate elderly population in terms of patient-reported outcomes and device- and treatment-related complications.

METHODS

In this single-center crossover randomized clinical trial (RCT), 10 edentulous participants received an implant in the lower midline and had their lower complete dentures converted to SIMOs. The participants received each attachment system for 3 mo in a randomized order, followed by measurement of patient satisfaction and oral health-related quality of life via the McGill Denture Satisfaction Questionnaire and the Oral Health Impact Profile for Edentulous People questionnaire, respectively. Complications were registered throughout the RCT. Patients were interviewed for their experiences with SIMOs and preference for one of the attachment systems. Quantitative analysis employed mixed linear models and chi-square tests (α = 0.05), whereas interview data underwent thematic analysis and, in turn, integration into quantitative data (mixed methods explanatory design).

RESULTS

All 10 randomized participants completed the trial. Mean ± SD general satisfaction was 92% ± 8% with Novaloc versus 85% ± 13% with Locator (mean difference, 9%; 95% CI, 1% to 17%). For specific McGill Denture Satisfaction Questionnaire items, only denture stability was significantly increased for Novaloc. Seven participants preferred Novaloc over Locator at the end of the RCT (chi-square, P = 0.045). No difference was found between the attachments in terms of oral health-related quality of life based on the Oral Health Impact Profile for Edentulous People and complications. Thematic analysis revealed high patient satisfaction with SIMOs, with denture stability the main criterion for their satisfaction and attachment preference.

CONCLUSION

Among elderly edentulous patients wearing SIMOs, Novaloc led to increased patient satisfaction and preference. Better patient-perceived denture stability may explain this result. The attachment systems exhibited similar short-term maintenance needs.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03126942 (first registered on April 13, 2017). Secondary identifiers: A03-M07-17A (McGill University, Institutional Review Board) and 2018-3873 (McGill University Health Centre, Research Ethics Board).

KNOWLEDGE TRANSFER STATEMENT

The results of this mixed methods study can be used by clinicians when choosing which attachment system to use for SIMOs. Results suggest that edentulous patients prefer attachments with a better-defined seating position, such as that of the Novaloc system, as opposed to the nylon matrix on metallic abutment of the Locator system.

The effect of triangular cross-section neck design on crestal bone stability in the anterior mandible: A retrospective study with a 5-year follow-up

OBJECTIVES

The objective of this study, which included a 5-year follow-up, was to compare peri-implant soft tissue health, crestal bone loss (CBL), and buccal bone thickness (BBT) around triangular cross-section neck (TN) or round neck (RN) implants, using cone-beam computed tomography.

MATERIALS AND METHODS

This study was initially designed as a prospective 1-year randomized controlled study and then extended with a 5-year retrospective evaluation of clinical and radiographic records. In the initial 1-year study, a total of 20edentulous patients receiving 40 implants with similar diameters were randomly assigned to the RN or TN groups using a split-mouth design. Pocket probing depths (PPD), plaque index (PI), and gingival index (GI) were recorded at postoperative month 12. CBL and BBT at three levels (0, -2, and -4 mm) were evaluated 1 year after insertion. Five years after insertion, PPD, PI, GI, CBL, and BBT were recorded as patients were recalled for clinical and radiographic monitoring.

RESULTS

Nineteen patients completed the study. After 5 years, no significant differences in PPD, PI, and GI scores and BBT values between the two groups (p > .05). The mean ± SD CBL values at the final follow-up visit were -0.71 ± 0.69 mm for TN and -1.03 ± 0.86 mm for RN (p < .01).

CONCLUSIONS

These results suggest better crestal bone preservation using implants with TN when compared to RN after a 5-year follow-up. However, TN showed similar results to RN regarding peri-implant soft tissue health and BBT.

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.

Using an Attachment System with PEEK Matrices for Single-Implant Overdentures: In Vitro Retention Force

Single-implant overdentures (SIOs) represent a major biomechanical challenge in terms of prosthetic retention. The Novaloc attachment system has the potential to overcome those challenges when used for SIOs, due to the use of PEEK matrices. This study compared the retentive force of the Novaloc attachment to the traditional Locator system, before and after cyclic insertion–removal cycles. Three Novaloc matrices (white, yellow, and green, corresponding to low, medium, and high retention, respectively) and Locator (medium retention) were tested, totalling four groups. Retentive force was measured using an Imada force gauge before and after 1095 insertion–removal cycles, corresponding to a year of SIO wearing. Retention was tested with the implants angulated at 0, 10, and 20°. Data for the different groups, angles, and cycling periods were tested via linear regression analysis and two-way ANOVA (α = 0.05). Although the Locator system yielded higher retention forces in general, it lost a much higher percentage of retention with cycling. This trend was similar with the three angles, with forces being inversely proportional to the implant angulation. The authors conclude that Novaloc may provide more reliable retention for SIOs due to their higher resistance to insertion–removal cycling.

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.

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.

Effect of supporting implants inclination on stability of fixed partial denture: A finite element study

The aim of this finite element study was to analyze effect of supporting implants inclination on stress distribution in the bone for a four-unit fixed partial denture. A three-dimensional finite element model of mandibular molar section of the bone to receive implants was constructed. Three implant-supported fixed partial dentures, with null, moderate and wide tilting, of 0°, 15° and 30° implant inclinations, respectively, were modeled. A mechanical load of 10 MPa was applied in coronal–apical direction on bridge framework at the regions of crowns positions. The finite element analysis was performed, and von Mises stress levels were calculated. Peak stress concentration in the cortical bone was observed mostly around the implant necks, in inter-implants line. There was favorable stress distribution during loading, with peak stress being 90.04 MPa for 0°, which decreased to 54.33 MPa for 15° and 46.36 MPa for 30° inclination. The supporting implants inclination in fixed partial denture plays an important role in stress distribution and may be helpful in preventing bone loss and implant failure. This phenomenon is likely to be more pronounced in bones of poor quality. Within the limitation of this study, it seems that the inclination of implants in fixed partial denture has a favorable effect on stress distribution pattern values around the supporting implants.

Is one dental mini-implant biomechanically appropriate for the retention of a mandibular overdenture? A comparison with Morse taper and external hexagon platforms

STATEMENT OF PROBLEM

Limited information is available to clinicians on the use of dental mini-implants (MI) as opposed to standard-diameter implants (SDIs) for the stabilization of implant-retained mandibular overdentures (MOs).

PURPOSE

The purpose of this in vitro and finite element analysis study was to analyze and compare the biomechanical behavior of MOs with either 1 or 2 implants with external hexagon (EH), Morse taper (MT) SDIs, and MIs.

MATERIAL AND METHODS

Thirty photoelastic models (n=30) of each group (n=5) of SDIs (EH-1, EH-2, MT-1, MT-2) and MI (MI-1, MI-2) were fabricated for posterior, peri-implant, and total maximum shear stress evaluation by quantitative photoelastic analysis. One specimen of each group was further used to create the 6 computational models to be analyzed by finite element analysis. The maximum von Mises values and stress maps were plotted for each ductile component. Two types of load were applied to the overdenture: a150-N load bilaterally and simultaneously on the first molar and a 100-N load on the incisal edge of the central incisors at a 30-degree angle. The data were subjected to the 2-way ANOVA test and the Tukey honestly significant difference test (α=.05).

RESULTS

The EH-2 and MT-2 showed the lowest posterior (P<.001) and total (P<.05) mean shear stress values. For peri-implant shear stress, no difference was found among all groups (P>.05). Regardless of the loading area, the MI-1 and MI-2 groups showed the lowest von Mises stress values. However, for implant housing, the MI-1 group, under incisor loading, presented greater stress, followed by MT-1, EH-1, EH-2, MI-2, and MT-2. The attachment was the most overloaded structure, with high values under incisor loading, especially for the groups with 2 implants (MT-2, EH-2) as compared with the other models.

CONCLUSIONS

Biomechanically, regardless of the implant number, MI is a promising rehabilitation method with similar peri-implant shear stress and lower von Mises stress on the implant when compared with SDIs for MOs.

Sensorial Ability, Mastication and Nutrition of Single-Implant Overdentures Wearers

Abstract The use of two-implant overdentures improves mastication of edentulous elderly patients. However, little is known about the effects of single-implant overdentures (SIO) on oral perception and masticatory function in such elders. This study compared the effects of conventional complete dentures (CD) and SIO on the oral sensorimotor ability (OSA), masticatory function, and nutritional intake of elderly people with residual alveolar mandibular height classified as Class III or IV according to the American College of Prosthodontics. Twelve elders first received new conventional CD, which were later converted to SIO. All variables were evaluated after use of each prosthesis for 2 months. To evaluate OSA, elders closed their eyes and orally identified test pieces prepared from raw carrots. A kinesiographic device was used to measure chewing movements during mastication of a test material (Optocal). Masticatory performance (MP) was determined with the sieving method, and a 3-day food diary verified nutrient intake based on a standard Brazilian Food Composition Table. Data were analyzed using the Wilcoxon signed rank test and Student’s paired t test (P < 0.05). OSA results did not differ according to prosthesis type. However, opening and closing velocities during chewing and MP increased after SIO insertion (P < 0.05). Although no difference was observed in the intake of most nutrients, sodium ingestion decreased after SIO insertion (P < 0.05). SIO use had no effect on OSA, but significantly improved mastication and sodium intake of elders with decreased residual ridges height (Brazilian Registry of Clinical Trials #RBR-3kgttj).

One-year prospective clinical study comparing patient satisfaction and masticatory performance of mandibular overdentures supported by one versus two implants

There is a lack of clinical evidence on mandibular overdentures (MOD) supported by a single implant.

Single-implant overdentures retained by the Novaloc attachment system: study protocol for a mixed-methods randomized cross-over trial

BACKGROUND

Overdentures retained by a single implant in the midline have arisen as a minimal implant treatment for edentulous mandibles. The success of this treatment depends on the performance of a single stud attachment that is susceptible to wear-related retention loss. Recently developed biomaterials used in attachments may result in better performance of the overdentures, offering minimal retention loss and greater patient satisfaction. These biomaterials include resistant polymeric matrixes and amorphous diamond-like carbon applied on metallic components. The objective of this explanatory mixed-methods study is to compare Novaloc, a novel attachment system with such characteristics, to a traditional alternative for single implants in the mandible of edentate elderly patients.

METHODS/DESIGN

We will carry out a randomized cross-over clinical trial comparing Novaloc attachments to Locators for single-implant mandibular overdentures in edentate elderly individuals. Participants will be followed for three months with each attachment type; patient-based, clinical, and economic outcomes will be gathered. A sample of 26 participants is estimated to be required to detect clinically relevant differences in terms of the primary outcome (patient ratings of general satisfaction). Participants will choose which attachment they wish to keep, then be interviewed about their experiences and preferences with a single implant prosthesis and with the two attachments. Data from the quantitative and qualitative assessments will be integrated through a mixed-methods explanatory strategy. A last quantitative assessment will take place after 12 months with the preferred attachment; this latter assessment will enable measurement of the attachments' long-term wear and maintenance requirements.

DISCUSSION

Our results will lead to evidence-based recommendations regarding these systems, guiding providers and patients when making decisions on which attachment systems and implant numbers will be most appropriate for individual cases. The recommendation of a specific attachment for elderly edentulous patients may combine positive outcomes from patient perspectives with low cost, good maintenance, and minimal invasiveness.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03126942 . Registered on 13 April 2017.

Modification of clinically short Locator abutments using laser welding

As dental implants continue to survive longer, managing and maintaining implant prostheses can be complicated by the lack of compatible parts or the discontinuation of implant systems. This report describes a laser welding procedure for the management of clinically short Locator abutments (Zest Anchors Inc) that lacked a commercially available, compatible alternative.

Mandibular complete denture versus single-implant overdenture: a systematic review of patient-reported outcomes

The single-implant mandibular overdenture (SIMO) has been proposed as an alternative for edentulous patients who are poorly adapted to their dentures due to low retention and stability of the conventional mandibular complete denture (CD). However, there is a lack of evidence regarding the effectiveness of SIMO, which can be measured by examining patient perception of treatment effects. The aim of this systematic review was to assess the comparative results of CD and SIMO treatments using patient-reported outcome measures. A literature search was carried out in PubMed, Scopus and Cochrane Central databases. The search included studies published up to July 2017. The focus question was: 'Do single-implant mandibular overdentures improve patient-reported outcomes compared to conventional complete dentures in edentulous patients?' Eligible studies were randomised clinical trials (RCT) and prospective studies. After initial screening for eligibility and full-text analysis, 11 studies were included for data extraction and quality assessment (five parallel-group RCTs, two crossover RCTs and four prospective studies). All studies reported marked improvement in satisfaction with the dentures and quality of life measures after SIMO treatment, irrespective of variations in implant treatment protocols and retention systems. Methodological considerations revealed a lack of evidence from RCTs on the comparative effectiveness of the two treatment strategies. Hence, although available evidence suggests considerable improvement in patient-reported outcomes following the insertion of a single implant to retain a mandibular denture, further well-designed comparative studies between SIMO and CD are required to improve the level of evidence and to support the indication of SIMO treatment in routine practice.

An International Survey among Prosthodontists of the Use of Mandibular Implant-Supported Dental Prostheses

PURPOSE

To evaluate the use of implant-supported overdentures (IOD) and implant-supported fixed dental prostheses (IFDP) in patients with edentulous mandibles among international prosthodontists.

MATERIALS AND METHODS

A questionnaire was sent by e-mail to all clinically active prosthodontists in the International College of Prosthodontists with questions related to implant treatment of the edentulous mandible performed in 2015.

RESULTS

One hundred and sixteen prosthodontists from 33 countries responded to the questionnaire. The vast majority of the responding prosthodontists was faculty or worked in private practice, and the great majority had performed treatment with mandibular implant-supported dental prostheses; however, two thirds of the respondents reported that <20% of the implant patients in their clinic had received treatment related to edentulous mandibles. The majority reported using 2 implants (84%), while 13% used 4 for overdenture retention. There were great variations regarding retention systems used for mandibular IODs; the most common was individual Locator attachments. Cost was considered the most common reason to choose mandibular IOD, There was a wide variation of materials used for mandibular IFDPs. The most common combination included milled titanium frameworks and acrylic resin teeth.

CONCLUSIONS

This survey, completed by 116 prosthodontists from 33 countries, showed that implant treatment for edentulous mandibles is common, but there was great variation among the respondents regarding amount of treatments performed, design, and materials used for the implant prostheses.

Cost-effectiveness analysis of the single-implant mandibular overdenture versus conventional complete denture: study protocol for a randomized controlled trial

Background

Preliminary clinical studies on the single-implant mandibular overdenture (SIMO) have reported favorable results as an alternative to the conventional complete dentures for rehabilitation of the edentulous mandible. Clinical and patient-reported outcomes were assessed but no evidence is available with respect to the cost-effectiveness of this treatment, which is particularly important to test whether the incremental cost associated with the implant treatment is justified facing the benefits from the intervention. Thus, the aim of this study is to assess the cost-effectiveness of single-implant mandibular overdentures.

Methods/design

This randomized clinical trial will include edentulous individuals who meet eligibility criteria. Participants will be randomized into one of the treatment groups: a conventional complete denture group or a single-implant mandibular overdenture group. Direct costs related to therapies in both groups will be identified, measured and valuated for 1 year after treatment. Oral health-related quality of life and satisfaction with the dentures will be the primary outcome variables. Incremental cost-effectiveness ratios will be estimated and graphically presented on cost-effectiveness planes. A Markov decision tree will be constructed to set out the consequences of the competing alternatives. Sensitivity analysis on the most important assumptions will be performed in order to assess the robustness of the model.

Discussion

This is the first trial-based cost-effectiveness study on single-implant mandibular overdentures. Specific challenges in designing the protocol are considered. The expected results are of high clinical relevance and may contribute to the decision-making process when choosing between different alternatives for the rehabilitation of the edentulous mandible.

Trial registration

ClinicalTrials.gov Identifier: NCT02710357, registered on 11 March 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1646-0) contains supplementary material, which is available to authorized users.

Predictive factors of sagittal stability after treatment of Class II malocclusions

OBJECTIVE

To determine the existence of factors permitting the prediction of sagittal stability after orthodontic treatment in patients with Angle Class II malocclusion.

MATERIALS AND METHODS

PubMed, EMBASE, and the Cochrane Library were searched up to March 2015. Inclusion criteria were longitudinal studies with at least 10 subjects investigating associations between at least one factor and stability, with an average minimum follow-up period of 2 years; stability measured using posttreatment sagittal dental changes; and orthodontic treatment including removable and/or fixed appliances with or without extractions. Two reviewers independently selected and assessed the quality of the articles.

RESULTS

The search strategy resulted in 1372 articles, of which 17 met the inclusion criteria. Large changes during treatment in molar and canine relationships were the only two factors found to be positively associated with relapse, but with limited evidence. Fourteen factors were found not to be predictive of relapse, also with limited evidence. These factors included treatment characteristics, patient pretreatment characteristics, and final posttreatment characteristics.

CONCLUSIONS

There is currently limited evidence to support the influence of factors predictive of sagittal stability following Class II malocclusion treatment. More high-quality prospective studies are needed, and functional factors possibly affecting relapse also need to be further assessed.

Dental implants in the elderly population: a systematic review and meta-analysis

OBJECTIVE

This systematic review was conducted to evaluate the outcome of dental implant therapy in elderly patients (≥65 years).

MATERIAL AND METHODS

Online database and hand searches were systematically performed to identify studies reporting on dental implants placed in the partially/completely edentulous jaws of elderly patients. Only prospective studies reporting on regular-diameter (≥3 mm), micro-rough surface implants were included in this review. Two investigators performed the search and data extraction. An inter-investigator reliability was verified using kappa statistics (κ). A meta-analysis was performed on implant survival rates, while the mean peri-implant marginal bone level changes (PI-MBL), technical/mechanical complications, and biological complications were reported descriptively.

RESULTS

The systematic search yielded 2221 publications, of which 11 studies were included for statistical analyses. The calculated κ for the various parameters extracted was κ = 0.818-1.000. A meta-analysis was performed on the post-loading implant survival rates at 1, 3, 5, and 10 years. The random-effects model revealed an overall 1-year implant survival of 97.7% (95% CI: 95.8, 98.8; I²  = 0.00%, P = 0.968; n = 11 studies). The model further revealed an overall implant survival of 96.3% (95% CI: 92.8, 98.1; I²  = 0.00%, P = 0.618; n = 6 studies), 96.2% (95% CI: 93.0, 97.9; I²  = 0.00%, P = 0.850; n = 7 studies), and 91.2% (95% CI: 83.4, 95.6; I²  = 0.00%, P = 0.381; n = 3 studies) for 3, 5, and 10 years, respectively. The reported 1-year average PI-MBL ranged between 0.1 and 0.3 mm, while the reported 5- and 10-year PI-MBL were 0.7 and 1.5 mm, respectively. Information obtained pertaining to the technical and biological complications in the included studies was inadequate for statistical analysis. The frequent technical/mechanical complications reported were abutment screw loosening, fracture of the overdenture prostheses, activation of retentive clips, ceramic chipping, and fractures. The common biological complication reported included peri-implant mucositis, mucosal enlargement, bone loss, pain, and implant loss.

CONCLUSIONS

This review provides robust evidence favoring dental implant therapy in elderly patients as a predictable long-term treatment option, in terms of implant survival, clinically acceptable PI-MBL changes, and minimal complications. Therefore, age alone should not be a limiting factor for dental implant therapy.

Some issues related to evidence-based implantology

This article reviews relevant dental literature to answer some frequent questions related to evidence-based implantology. There are hundreds of implant systems on the market, but the majority lack clinical documentation. Recommended number of implants for full-arch fixed prostheses is four or five in the mandible but at least six in the maxilla. Less expensive implant-retained overdentures make implant treatment available to a greater portion of edentulous subjects. Mandibular overdentures on two implants, and even one implant, have shown excellent long-term outcomes. In the maxilla, less than four implants are not recommended for good results. Single implant restorations have good prognosis, but placement of the implant should be postponed until adulthood. Osseointegrated implants have revolutionized clinical dentistry. However, in a global perspective, implants make up only a small part of all prosthodontic treatment. Knowledge and skill in conventional prosthodontics must be maintained as it will remain the most common part of the specialty.