Masticatory function in patients with an extremely resorbed mandible restored with mandibular implant-retained overdentures: comparison of three types of treatment protocols

Four-year assessment of masticatory function in mandibular overdenture wearers: A randomised clinical trial comparing two to four implants to retain the prosthesis

BACKGROUND

Limited data exist on the mid- to long-term masticatory capacity of mandibular overdenture (IOD) wearers, particularly regarding the use of posterior implants to retention.

OBJECTIVES

To periodically evaluate mastication of IOD wearers, comparing the effectiveness of two to four implants to retain the prosthesis.

METHODS

In a randomised controlled clinical trial, 20 complete edentulous patients (14 women), aged 51-84 years (mean age 69.1 ± 9.6), received new bimaxillary complete dentures (CD). After adaptation, baseline measurements of masticatory performance (X50) and swallowing threshold were conducted using the sieving method. Patients were then randomly assigned to groups: control (two intra-foraminal regular implants) and experimental (two intra-foraminal regular implants and two extra-short posterior implants) (n = 10 each). After 4 months, implants were splinted, and a new mandibular IOD was fabricated with bar/clip retention. Mastication was reassessed after 6, 12, and 48 months, and data analysed with repeated measures ANOVA and Sidak's post hoc (α = 0.05).

RESULTS

Despite a loss of two patients per group, masticatory performance significantly improved after mandibular IOD installation (p = .031) in both groups (p = .670). A second improvement was observed after 6 months (p = .027), with no subsequent changes (p > .05). Swallowing threshold improvements were noted with IOD, and no discernible differences between groups were observed (p > .05).

CONCLUSION

Masticatory function significantly improved after mandibular IOD installation, with the number of implants demonstrating minimal influence.

CLINICAL TRIAL REGISTRATION

The present study was not registered in a public database, as mandated. It is important to note that the recommendation for registration was initiated in 2017 by the Committee of Medical Journal Editors, while patient inclusion in the research took place in 2016. Given that the data presented in this manuscript cover a follow-up period of up to 4 years post-surgical intervention, delayed registration was not feasible.

Maxillary overdentures supported by four or six implants in the anterior region: 10-year randomized controlled trial results

AIM

To evaluate bar-supported maxillary implant overdenture treatment when supported by either four or six implants after 10 years.

MATERIALS AND METHODS

Edentulous subjects with maxillary denture complaints and ample bone volume to facilitate implants in the anterior region of the maxilla were planned for implant overdenture treatment, randomized to receive either four implants (n = 25) or six implants (n = 25) and subsequently evaluated after 10 years of function. Outcome variables included peri-implant bone-level changes, implant and overdenture survival, complications, presence of plaque, calculus and bleeding, degree of peri-implant inflammation, probing depth and patient satisfaction. Differences between the groups and between evaluation periods were tested with a Student's t-test.

RESULTS

Fourteen patients with totally 72 implants were lost to follow-up. Two patients from the six-implant group experienced implant loss (four implants), resulting in 96.1% implant survival in this group versus 100% survival in the four-implant group. Clinical, radiographical and patient-reported outcome measures did not differ statistically significant between the two groups. Patients from both groups were generally quite satisfied with the result after 10 years.

CONCLUSIONS

Similar and favourable outcomes are seen in bar-supported maxillary overdentures on either four or six anteriorly placed implants after a 10-year evaluation period.

Bone Quality Assessment of Dental Implant Recipient Sites

The term bone quality is not clearly defined and depends on many factors, such as bone density, bone vascularity, bone metabolism and other factors that may affect implant outcome. The assessment of bone volume and bone density is most common in planning the treatment of dental implants. Bone quality is an important predictor of primary implant stability, which influences the future implant osseointegration. Numerous classifications have been described for the evaluation of bone density. The most commonly used has been the one proposed by Lekholmu and Zarb. For the objective evaluation of bone density, conventional computed tomography (CT) or Cone Beam Computed tomography (CBCT), have been proposed. Both methods are reliable for the measurement of bone density, but preference is given to CBCT, due to the lower radiation doses, greater comfort for the patient and the lower prices. Pre-operatively defined bone density is a good indicator of the future success of implant therapy. In addition to the bone density, vascularity of the jawbone is an important factor of the quality of the bone for the osseointegration of dental implants. Laser Doppler is a simple method that can determine the vascularity of bone during implant insertion. The development of modern diagnostic methods for assessing the quantity and quality of the jawbone has enabled easier implant planning and has provided a secure outcome.

A randomised crossover clinical trial of masticatory function in complete denture wearers with conventional and lingualised balanced occlusion

OBJECTIVES

The purposes of the present study were as follows: (1) to conduct a randomised crossover clinical trial to evaluate masticatory performance in wearers of conventional complete dentures in both arcs with conventional balanced occlusion (CBO) and lingualised balanced occlusion (LBO), using almonds as natural test food chewed for (a) 30 chewing cycles, (b) 40 chewing cycles and (c) until the subject felt ready to swallow and (2) to perform a randomised crossover clinical trial of oral health self-perception through the Geriatric Oral Health Assessment Index (GOHAI) questionnaire.

BACKGROUND

During rehabilitation with full dentures, achieving stability and retention is essential for masticatory performance. A factor that can act is the appropriate occlusal scheme to be used, although the literature is full of discussions as to the most suitable occlusal scheme to be used, being CBO and LBO the most used in complete dentures.

MATERIALS AND METHODS

The clinical trial was conducted with 30 participants (14 males and 16 females; average age 65.8 years). A base of interchangeable posterior teeth in the lower dentures was used, thereby changing the occlusal schemes without needing to make another complete denture. The masticatory tests and GOHAI application were conducted in two sessions: first with each occlusal scheme, and second only after participants did not report discomfort with dentures. The analysis of variance for the mixed repeated-measures test (ANOVA) was used to verify the results (α = 0.05).

RESULTS

The results showed no difference in masticatory performance according to the occlusal scheme (P = .519). The masticatory performance increased with the number of cycles (P < .001) tested, regardless of the type of occlusion scheme, and oral health self-perception was higher after the second masticatory evaluation session (P = .027).

CONCLUSION

The masticatory performance was similar between the two occlusal schemes, increasing according to the number of chewing cycles. The adaptive period is relevant, regardless of the occlusion scheme, because the time factor was decisive for the improvements noted in the oral health self-perception of the participants (according to the GOHAI results).

General health, healthcare costs and dental care use of elderly with a natural dentition, implant-retained overdenture or conventional denture: an 8-year cohort of Dutch elderly (aged 75 and over)

Background

Cross-sectional studies have shown that elderly with a natural dentition have better general health than edentulous elderly, but this has not been confirmed in studies with longitudinal design.

Methods

This prospective longitudinal study with a follow-up of 8 years aimed to assess differences in general health, healthcare costs and dental care use between elderly with a natural dentition and edentulous elderly wearing implant-retained or conventional dentures. Based on data of all national insurance claims for dental and medical care from Dutch elderly (aged ≥75 years) general health outcomes (chronic conditions, medication use), healthcare costs and dental care use could be assessed of three groups of elderly, viz. elderly with a natural dentition, elderly with conventional dentures and elderly with implant-retained overdentures.

Results

At baseline (2009), a total of 168,122 elderly could be included (143,199 natural dentition, 18,420 conventional dentures, 6503 implant-retained overdentures). Here we showed that after 8 years follow-up elderly with a natural dentition had more favorable general health outcomes (fewer chronic conditions, less medication use), lower healthcare costs and lower dental costs – but higher dental care use – than edentulous elderly. At baseline the general health of elderly with an implant-retained overdentures resembled the profile of elderly with a natural dentition, but over time their general health problems became comparable to elderly with conventional dentures.

Conclusions

It was concluded that elderly with a natural dentition had significant better health and lower healthcare costs compared to edentulous elderly (with or without dental implants).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02427-z.

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.

Mandibular dental implant placement immediately after teeth removal in head and neck cancer patients

BACKGROUND

Little is known about immediate implant placement in head and neck cancer patients. We studied implant survival and functional outcomes of overdentures fabricated on implants placed immediately after removal of the lower dentition during ablative surgery or preceding primary radiotherapy (RT).

METHODS

Inclusion criteria were primary head and neck cancer, dentate lower jaw, and indication for removal of remaining teeth. Two implants to support a mandibular overdenture were placed immediately after extraction of the dentition during ablative surgery, or prior to starting primary radiotherapy. Standardized questionnaires and clinical assessments were conducted (median follow-up 18.5 months, IQR 13.3).

RESULTS

Fifty-eight implants were placed in 29 patients. Four implants were lost (implant survival rate 93.1%). In 9 patients, no functional overdenture could be made. All patients were satisfied with their dentures.

CONCLUSIONS

Combining dental implant placement with removal of remaining teeth preceding head neck oncology treatment results in a favorable treatment outcome.

Effect of mucosa thicknesses on stress distribution of implant-supported overdentures under unilateral loading: Photoelastic analysis

INTRODUCTION

The aim of this study was to evaluate the effect of different heights of attachment and mucosa thicknesses on the stress distribution of two implant-retained mandibular overdenture designs under loading using the photoelastic stress analysis method.

MATERIALS AND METHODS

Six photoelastic models of an edentulous mandibula were fabricated with two solitary implants that were placed in the canine regions. The attachment systems studied were ball and locator stud attachments. Both the ball and locator groups included three models that had different residual ridge heights so as to provide different mucosa thicknesses (1 mm-1 mm, 1 mm-2 mm, 1 mm-4 mm). A static vertical force of 135 N was applied unilaterally (each on the right then the left side) to the central fossa of the first molars. Models were positioned in the field of a circular polariscope to observe the distribution of isochromatic fringes around the implants and the interimplant areas under loading. The photoelastic stress fringes were monitored and recorded photographically.

RESULTS

The ball attachment groups showed higher stress values than did the locator groups under loading. Both attachment systems produced the lowest stress values in stimulated 1 mm-1 mm mucosa thickness models. The models with 1 mm-2 mm mucosa thicknesses showed higher stress values than did other models for both attachment systems. The highest stress value observed around both attachment systems was the moderate level in all test models.

CONCLUSION

In different height mucosa thicknesses, locator attachment models distributed the load to the other side of the implant and its surrounding tissue, whereas the ball attachment did not. Regardless of mucosal thickness and attachment type, the implant on the loading side was subjected to the highest stress concentration.

Changes in oral health-related quality of life after oral rehabilitation with dental implants in patients following mandibular tumor resection

Oral rehabilitation with prosthodontic treatment considerably influences the well-being and quality of life of patients after ablative oral tumor surgery. This study evaluated the effects of implant-supported prostheses (ISPs) on oral health-related quality of life (OHRQoL) and chewing ability in 10 patients who requested ISPs after mandibular oral tumor resection. OHRQoL was assessed using the Japanese version of the Oral Health Impact Profile (OHIP-49) before and one year after ISP placement. Chewing ability, including self-assessed masticatory ability and occlusal force, was examined at one year after ISP placement. The initial mean total OHIP-49 score of 65.3 ± 9.79 decreased to 46.0 ± 8.14 at one year after ISP placement. Mean OHIP-49 score decreased in all domains, whereas self-assessed masticatory ability increased within one year of ISP placement. There were no significant differences between prosthesis types with respect to the mean OHIP-49 score or self-assessed masticatory ability. In conclusion, ISP placement improves OHRQoL and the self-assessed masticatory ability. Moreover, the prosthesis type might not significantly affect OHRQoL.

Mandibular implant-supported overdentures in (frail) elderly: A prospective study with 20-year follow-up

Purpose

To prospectively assess long‐term (20 year) clinical, radiographic, and patient‐reported outcomes of an elderly population provided with mandibular implant‐supported overdentures.

Materials and Methods

A total of 53 elderly (aged ≥60 years at the time of treatment) were provided with two endosseous implants supporting a mandibular overdenture and a conventional maxillary denture. Outcome parameters—including implant loss, plaque index, gingival index, bleeding index, presence of calculus, probing depth, and satisfaction with implant‐supported overdenture—were scored 1, 5, 10, and 20 years after prosthetic treatment. Radiographic analysis was performed to assess peri‐implant bone changes. At the 20‐year evaluation, frailty (Groningen Frailty Index) and quality of life (EuroQol 5D) were additionally assessed.

Results

A total of 15 patients completed the 20‐year follow‐up. The 20‐year implant survival rate was 92.5%. Plaque index, bleeding index, and probing depth increased slightly over time, while gingival index and presence of calculus remained unchanged. Radiographic analysis revealed minor marginal bone loss during the first 10 years and no further loss thereafter. Participants were very satisfied with their prosthesis and reported a good quality of life. At the 20‐year evaluation, 64.3% of the patients were classified as frail.

Conclusions

The long‐term survival of implants supporting a mandibular overdenture is high. Although most elderly in the study became frail over time, peri‐implant health and marginal bone level remained at a satisfactory level.

Masticatory ability improves after maxillary implant overdenture treatment: A randomized controlled trial with 1-year follow-up

BACKGROUND

The effect of maxillary implant overdentures on masticatory ability in edentulous patients with complaints regarding their conventional maxillary dentures is unknown.

PURPOSE

To assess the change in objective masticatory ability (mixing ability index, MAI), patient reported masticatory ability (questionnaire), and patient satisfaction (GSS) after maxillary implant overdenture treatment with either solitary attachments or bars.

MATERIALS AND METHODS

Two groups randomly received four-implant maxillary overdentures on either solitary attachments (group I, n = 25) or bars (group II, n = 25). The MAI, questionnaire, and GSS were scored before (T0) and 12 months (T12) after treatment.

RESULTS

After treatment, both groups had significantly better MAI outcomes, better questionnaire scores and better GSS. Post-treatment questionnaire scores and GSS were significantly better for group II. Before treatment a strong, positive correlation between the MAI and the questionnaire was found for all participants who had had full conventional dentures combined (group I, n = 17; group II, n = 3).

CONCLUSION

Mixing ability was the same for all the participants treated with maxillary implant overdentures on either solitary attachments or bars. Patient reported masticatory ability and satisfaction was better for participants treated with maxillary implant overdentures on bars. There was a correlation between MAI and patient reported masticatory ability in participants with full conventional dentures.

Four or six implants in the maxillary posterior region to support an overdenture: 5-year results from a randomized controlled trial

OBJECTIVE

To compare clinical and patient-reported outcomes when providing maxillary overdentures on four bar- and six bar-connected implants placed in the posterior region during a 5-year follow-up period.

MATERIALS AND METHODS

Sixty-six fully edentulous patients with functional maxillary denture complaints and insufficient bone volume to allow implant placement were scheduled for a maxillary sinus floor elevation procedure with bone from the anterior iliac crest and randomized to receive either four or six implants in the posterior maxilla and four implants in the mandible. After 3 months of osseointegration, a bar-supported overdenture was constructed. Maxillary implant survival, overdenture survival, clinical scores, peri-implant bone height changes and patient satisfaction were assessed.

RESULTS

Sixty patients completed the 5-year follow-up. Implant survival was 100% in the four-implant group and 99.5% in the six-implant group. No new overdentures had to be made in the four-implant group, and three new overdentures were made in the six-implant group due to excessive wear of the denture base and teeth (90.9% overdenture survival). Clinical parameters did not differ significantly between groups. Mean marginal bone loss compared to baseline was 0.58 ± 0.51 mm in the four-implant group and 0.60 ± 0.58 mm in the six-implant group, respectively. Overall, patient satisfaction improved significantly, but did not differ between groups.

CONCLUSION

Following a bilateral maxillary sinus floor elevation procedure, a bar-supported overdenture on four implants in the posterior maxillary region is not inferior to an overdenture supported by six implants after a 5-year evaluation period in patients with functional maxillary denture complaints and marked posterior resorption (Clinical trial registration number: NTR2969).

Surface roughness implant-retained mandibular bar and ball joint overdentures and adherence of microorganisms

Objective:

The aim of this study is to assess the surface roughness of the implant-retained mandibular bar overdenture (BOD) and the implant-retained mandibular ball joint overdenture (BJOD) in jaw and its relation with the adhesion of molds and yeasts and mesophyll aerobe, in time 30 and 180 days in mouth.

Materials and Methods:

Five-systems titanium bar CARES^® and synOcta^® Straumann^® Dental Implant System, Holding AG Inc., Basel, Switzerland (BOD), and five-systems joint ball Klockner^® Implant System; Soadco Inc., Escaldes-Engordany; Andorra (BJOD), were used in two parallel groups of five participants, in an essay to simple blind person. To 30 and 180 days, the overdentures were withdrawn and evaluated the Ra: ųm. SJ-301^® Mitutoyo Corporation Inc., Kanagawa, Japan, and the adhesion of microorganisms (colony-forming unit/ml).

Results:

The results were as follows: the R_a: Um (30^th and 180^th): BOD, 0.965–1.351; BJOD, 1.325–2.384. Adhesion: Molds and yeasts, BOD, 2.6 × 10² and 4.6 × 10³; BJOD, 3.0 × 10² and 5.3 × 10⁴. Adhesion: Mesophyll aerobe, BOD, 3.8 × 10⁶ and 5.8 × 10⁶; BJOD, 4.3 × 10⁶ and 7.1 × 10⁷.

Conclusions:

At 30 days (P = 0.489), there were no differences in BOD and BJOD for adhesion of molds and yeasts and mesophyll aerobe between both overdentures. At 180 days (P = 0.723), there were differences in the adhesion of mold and yeast and mesophyll aerobe, being greater in BJOD.

Maxillary implant-supported overdentures opposed by (partial) natural dentitions: a 5-year prospective case series study

The aim of this study was to assess the 5-year treatment outcome of maxillary implant-retained overdentures opposed by natural antagonistic teeth. Fifty consecutive patients received maxillary overdentures supported by six dental implants. Implants were placed in the anterior region, if enough bone was present (n = 25 patients) Implant were placed in the posterior region if implant placement in the anterior region was not possible (n = 25 patients). Variables assessed included survival of implants, condition of hard and soft peri-implant tissues and patients' satisfaction. The five-year implant survival rate was 97·0% and 99·3%, and mean radiographic bone loss was 0·23 and 0·69 mm in the anterior and posterior group, respectively. Median scores for plaque, calculus, gingiva, bleeding and mean scores for pocket probing depth were low and stayed low. Patients' satisfaction after treatment was high in both groups. Within the limits of this 5-year study, it is concluded that six dental implants (placed in the anterior or posterior region) connected with a bar and opposed to natural antagonistic teeth result in acceptable results for clinical parameters and good outcomes for marginal bone level changes and patient satisfaction.

Short-term follow-up of masticatory adaptation after rehabilitation with an immediately loaded implant-supported prosthesis: a pilot assessment

Background

When teeth are extracted, sensory function is decreased by a loss of periodontal ligament receptions. When replacing teeth by oral implants, one hopes to restore the sensory feedback pathway as such to allow for physiological implant integration and optimized oral function with implant-supported prostheses. What remains to be investigated is how to adapt to different oral rehabilitations.

The purpose of this pilot study was to assess four aspects of masticatory adaptation after rehabilitation with an immediately loaded implant-supported prosthesis and to observe how each aspect will recover respectively.

Methods

Eight participants with complete dentures were enrolled. They received an implant-supported acrylic resin provisional bridge, 1 day after implant surgery. Masticatory adaptation was examined by assessing occlusal contact, approximate maximum bite force, masticatory efficiency of gum-like specimens, and food hardness perception.

Results

Occlusal contact and approximate maximum bite force were significantly increased 3 months after implant rehabilitation, with the bite force gradually building up to a 72% increase compared to baseline. Masticatory efficiency increased by 46% immediately after surgery, stabilizing at around 40% 3 months after implant rehabilitation. Hardness perception also improved, with a reduction of the error rate by 16% over time.

Conclusions

This assessment demonstrated masticatory adaptation immediately after implant rehabilitation with improvements noted up to 3 months after surgery and rehabilitation. It was also observed that, despite gradually improved bite force in all patients, masticatory efficiency and food hardness perception did not necessarily follow this tendency. The findings in this pilot may also be used to assess adaptation of oral function after implant rehabilitation by studying the combined outcome of four tests (occlusal contact, maximum bite force, masticatory efficiency, and food hardness perception).

Maxillary overdentures supported by four or six implants in the anterior region: 5-year results from a randomized controlled trial

OBJECTIVE

To compare a four- and six-implant maxillary overdenture after an observation period of 5 years.

MATERIAL AND METHODS

Fifty subjects with functional problems concerning their maxillary denture, who had ample bone volume in the anterior region to place four or six implants, were included and randomly assigned to either group. Implant and overdenture survival, clinical performance, marginal bone loss and patient satisfaction were assessed.

RESULTS

Forty-six patients completed the 5-year follow-up. One implant failed in the six implants group (99.2% survival) and none in the four implants group (100% survival). No overdentures had to be replaced during the observation period and the number of complications was limited. Clinical function was good, with no difference in clinical parameters between the groups. Mean marginal bone resorption was 0.50 ± 0.37 and 0.52 ± 0.43 mm in the four and six implant group respectively.

CONCLUSION

In patients with functional complaints of their maxillary denture, bar-supported overdentures on four implants in the anterior maxillary region were not inferior to overdentures supported by six implants after 5 years of function. Implant survival and patient satisfaction were high, clinical parameters favourable, bone loss and complications to the denture were minor in both groups (Clinical trial registration number: NTR2969).

Power spectrum density analysis for the influence of complete denture on the brain function of edentulous patients - pilot study

PURPOSE

This pilot study was to find the influence of complete denture on the brain activity and cognitive function of edentulous patients measured through Electroencephalogram (EEG) signals.

MATERIALS AND METHODS

The study recruited 20 patients aged from 50 to 60 years requiring complete dentures with inclusion and exclusion criteria. The brain function and cognitive function were analyzed with a mental state questionnaire and a 15-minute analysis of power spectral density of EEG alpha waves. The analysis included edentulous phase and post denture insertion adaptive phase, each done before and after chewing. The results obtained were statistically evaluated.

RESULTS

Power Spectral Density (PSD) values increased from edentulous phase to post denture insertion adaption phase. The data were grouped as edentulous phase before chewing (EEG p1-0.0064), edentulous phase after chewing (EEG p2-0.0073), post denture insertion adaptive phase before chewing (EEG p3-0.0077), and post denture insertion adaptive phase after chewing (EEG p4-0.0096). The acquired values were statistically analyzed using paired t-test, which showed statistically significant results (P<.05).

CONCLUSION

This pilot study showed functional improvement in brain function of edentulous patients with complete dentures rehabilitation.

Comparison of masticatory efficiency, patient satisfaction for single, two, and three implants supported overdenture in the same patient: A pilot study

STATEMENT OF PROBLEM

Over 30% of the world population suffers from edentulism. Implant supported overdenture have been a relatively successful treatment option for edentulism and have shown to slowed the rate of residual resorption and maintain the vertical height of the residual.

PURPOSE

The purpose of this study was to measure patient masticatary efficiency and satisfaction with the mandibular one-, two-, and three-implant-retained overdenture therapy when compared with conventional denture in a the same patients.

MATERIALS AND METHODS

Ten complete edentulous patients, who were wearing conventional complete dentures, were involved in this study. Three single piece endosseous implant of 3.0 mm in diameter and 13 mm in length were surgically placed in the mandible in the region of B, C, and D. Mandibular denture was connected for single, two, and three implant supported overdenture periodically and checked for masticatory efficiency using a bite gauge and patient satisfaction using a questionnaire.

RESULTS

Statistical analysis was done using Wilcoxon signed rank test. Four groups of bite forces when compared to each other. Group 1 was compared with Group 2, with the statistical value showing significance. Signed rank test showed no significance (0.268) when Group 2 was compared with Group 3. When Group 3 was compared with Group 4, and Group 1 compared with Group 4, rank test showed significant values. Four groups were compared with each other for patient satisfaction, Group 1 was compared with Group 2, with the statistical value showing no significance.

CONCLUSIONS

A single midline implant supported overdenture can be considered as a suitable and cost-effective treatment option over conventional denture. The study concludes that masticatory efficiency of this single midline implant supported overdenture is better than the conventional complete denture.

Functional adaptation of the masticatory system to implant-supported mandibular overdentures

OBJECTIVES

The purpose of this study was to investigate the adaptation behavior of the stomatognathic system after immediate loading (24 to 72 h after surgery) of two implants supporting mandibular overdentures, assessed on insertion and three months later. The study hypothesis was that insertion of the overdentures would significantly change masticatory performance and muscle activity at both times.

MATERIAL AND METHODS

Thirty subjects (nine female, mean age 69.64 ± 11.81 years; 21 male, mean age 68.67 ± 7.41 years) who participated in a randomized clinical trial were included in the study. Each patient was examined three times: (i) at baseline, after already having worn new dentures for three months (T1); (ii) immediately after insertion of the overdentures on the implants (T2); and (iii) after an adaptation period of three months (T3). Examination comprised assessment of masticatory performance with artificial test food (Optocal), and simultaneous bilateral surface EMG recording of the masseter and anterior temporalis muscles. Particle-size distribution (representative value X₅₀ ), maximum muscle contraction (MVC), and total muscle work (TMW; area under the curve) were compared by use of repeated-measures analysis of variance (ANOVA).

RESULTS

At T3, all measured variables (i.e., masticatory performance and muscle activity) were significantly different from those at T1. At T2, no significant changes were observed. The study hypothesis had to be rejected for T2 but accepted for T3.

CONCLUSION

Functional rehabilitation (in terms of masticatory performance and masticatory muscle activity) does not occur immediately after immediate loading of two implants with mandibular overdentures, but requires a significant time for functional improvement.

Repair of a fractured implant overdenture gold bar: A clinical and laboratory technique report

This clinical report explains a convenient, efficient, yet effective alternative for management of fractured substructure cast bars for implant-retained overdentures. The technique allows the fracture to be repaired at low cost and short time without remaking the substructure and the denture and further allowing the patient to keep their denture. The report sketches the clinical and laboratory procedures involved in the repair.

A comparison between 4 and 6 implants in the maxillary posterior region to support an overdenture; 1-year results from a randomized controlled trial

OBJECTIVE

To compare the treatment outcome of 4 vs. 6 bar-connected implants in the posterior region of the maxilla to support an overdenture during a 1-year follow-up period.

MATERIALS AND METHODS

Sixty-six edentulous patients with an insufficient amount of bone volume in the maxilla to place implants were asked to participate in this study. Randomization assigned patients to either 4 or 6 implants. In all patients, a maxillary sinus floor elevation procedure with bone from the iliac crest was performed, and after a 3-month healing period, 4 or 6 dental implants were inserted in the maxillary posterior region in a one-stage procedure. After 3 months of osseointegration, a bar-supported overdenture was constructed. Implant survival, overdenture survival, clinical scores, peri-implant bone height changes and patients' satisfaction were assessed. Study analysis was performed according a non-inferiority design.

RESULTS

All patients completed the one-year follow-up. After a functional period of 1-year, implant survival was 100% in the 4 implants group and 99.5% in the 6 implants group. Overdenture survival was 100% in both groups. Mean clinical scores were very low and did not significantly differ between groups. Mean marginal bone resorption was 0.35 ± 0.31 mm and 0.46 ± 0.34 mm in the 4 and 6 implants group, respectively. Patients' satisfaction improved significantly in both groups, but did not differ between groups.

CONCLUSION

A bar-supported overdenture on 4 implants in the posterior maxillary region is not inferior to an overdenture supported by 6 bar-connected dental implants.

Maxillary overdentures supported by four or six implants in the anterior region; 1-year results from a randomized controlled trial

OBJECTIVE

Comparing treatment outcome of four and six bar-connected implants in the anterior maxillary region to support an overdenture during a 1-year follow-up period.

MATERIAL AND METHODS

Fifty edentulous patients with lack of retention and stability of the upper denture, but with sufficient bone volume to place implants in the anterior maxillary region, were selected. Randomization assigned patients to either four or six implants. Implant survival, overdenture survival, clinical scores, radiographic bone height changes, and patients' satisfaction were assessed.

RESULTS

Forty-nine patients (one drop out) completed the 1-year follow-up. After 1 year, implant survival was 100% in the four implants group and 99.3% in the six implants group (one implant lost). Overdenture survival was 100% in both groups. Mean clinical scores were low and did not differ between groups (independent Student's t-test). Mean marginal bone resorption was 0.24 ± 0.32 mm in the four implants group and 0.25 ± 0.29 mm in the six implants group. Patients' satisfaction had improved in both groups (paired Student's t-test).

CONCLUSION

Bar-supported overdentures on four implants in the anterior maxillary region are not inferior to overdentures supported by six bar-connected implants. Implant survival was high, peri-implant conditions were healthy and patients' satisfaction had increased significantly in both groups.

Comparison of particle-size distributions determined by optical scanning and by sieving in the assessment of masticatory performance

Aim of this study was to introduce a feasible and valid technique for the assessment of masticatory performance that is comparable to the standard sieving method. Twenty-one chewing samples (Optosil) comminuted by healthy dentate adults were analysed with a sieving and scanning method. Scanning was performed using a conventional flatbed scanner (1200dpi). All scanned images underwent image analysis (ImageJ), which yielded descriptive parameters such as area, best-fitting ellipse for each particle. Of the 2D-image, a volume was estimated for each particle, which was converted into a weight. To receive a discrete distribution of particle sizes comparable to sieving, five chewing samples were used to calculate a size-dependent area-volume-conversion factor. The sieving procedure was carried out with a stack of 10 sieves, and the retained particles per sieve were weighed. The cumulated weights yielded by either method were curve-fitted with the Rosin-Rammler distribution to determine the median particle size x(50) . The Rosin-Rammler distributions for sieving and scanning resemble each other. The distributions show a high correlation (0·919-1·0, n= 21, P<0·01, Pearson's correlation coefficient). The median particle sizes vary between 3·83 and 4·77mm (mean: 4·31) for scanning and 3·53 and 4·55mm (mean: 4·21) for sieving. On average, scanning overestimates the x(50) values by 2·4%. A modified Bland-Altman plot reveals that 95% of the x(50) values fall within 10% of the average x(50) . The scanning method is a valid, simple and feasible method to determine masticatory performance.

Vertical augmentation with interpositional blocks of anorganic bovine bone vs. 7-mm-long implants in posterior mandibles: 1-year results of a randomized clinical trial

OBJECTIVES

To evaluate whether 7-mm-long implants could be an alternative to longer implants placed in vertically augmented posterior mandibles.

MATERIALS AND METHODS

Sixty patients with posterior mandibular edentulism with 7-8 mm bone height above the mandibular canal were randomized to either vertical augmentation with anorganic bovine bone blocks and delayed 5-month placement of ≥10 mm implants or to receive 7-mm-long implants. Four months after implant placement, provisional prostheses were delivered, replaced after 4 months, by definitive prostheses. The outcome measures were prosthesis and implant failures, any complications and peri-implant marginal bone levels. All patients were followed to 1 year after loading.

RESULTS

One patient dropped out from the short implant group. In two augmented mandibles, there was not sufficient bone to place 10-mm-long implants possibly because the blocks had broken apart during insertion. One prosthesis could not be placed when planned in the 7 mm group vs. three prostheses in the augmented group, because of early failure of one implant in each patient. Four complications (wound dehiscence) occurred during graft healing in the augmented group vs. none in the 7 mm group. No complications occurred after implant placement. These differences were not statistically significant. One year after loading, patients of both groups lost an average of 1 mm of peri-implant bone. There no statistically significant differences in bone loss between groups.

CONCLUSIONS

When residual bone height over the mandibular canal is between 7 and 8 mm, 7 mm short implants might be a preferable choice than vertical augmentation, reducing the chair time, expenses and morbidity. These 1-year preliminary results need to be confirmed by follow-up of at least 5 years.

Five-year follow-up of oral functioning and quality of life in patients with oral cancer with implant-retained mandibular overdentures

BACKGROUND

The purpose of this prospective study was to assess the quality of life (QOL) and oral functioning of patients with oral cancer up to 5 years after prosthodontic rehabilitation with mandibular implant-retained overdentures.

METHODS

Fifty patients who had received implants during ablative surgery were evaluated by standardized questionnaires before and after oncological and prosthetic treatment.

RESULTS

In 20 of 24 surviving patients, the dentures were functional after 5 years. In these survivors, oral function remained unchanged during this period. In the 6 patients with concurrent comorbidity, global health and QOL had deteriorated, while in the patients without comorbidity, global health and QOL were very high. Five-year survivors had a higher global health and better oral functioning at the 1-year evaluation than nonsurvivors.

CONCLUSION

Oral function and denture satisfaction were high and did not change over time for survivors. Deterioration in overall global health and QOL was associated with concurrent comorbidity.

Benefits of dental implants installed during ablative tumour surgery in oral cancer patients: a prospective 5-year clinical trial

OBJECTIVE

This prospective study assessed treatment outcome and patient satisfaction of oral cancer patients with a mandibular overdenture on implants up to 5 years after treatment.

MATERIALS AND METHODS

At baseline, 50 consecutive edentulous oral cancer patients, in whom prosthetic problems were expected after oncological treatment, were evaluated by standardized questionnaires and clinical assessments. All implants were installed during ablative tumour surgery in native bone in the interforaminal area. About two-thirds of the patients (n=31) had radiotherapy post-surgery (dose >40 Gy in the interforaminal area).

RESULTS

At the 5-year evaluation, 26 patients had passed away and four patients had to be excluded from the analyses, because superstructures were not present, due to persistent local irritation (n=2), loss of three implants (n=1) and the impossibility of making an overdenture related to tumour and oncological surgery-driven anatomical limitations (n=1). In the remaining 20 patients, the prosthesis was still in function (76 implants). During the 5-year follow-up, total 14 implants were lost, 13 in irradiated bone (survival rate 89.4%, dose >40 Gy) and one in non-irradiated bone (survival rate 98.6%). Peri-implant tissues had a healthy appearance and remained healthy over time. Patients were satisfied with their dentures.

CONCLUSIONS

It was concluded that oral cancer patients can benefit from implants installed during ablative surgery, with a high survival rate of the implants, a high percentage of rehabilitated patients and a high denture satisfaction up to 5 years after treatment.

Overdenture with immediate load: mastication and nutrition

Lower conventional complete dentures were converted to overdentures retained by two implants with an immediately loaded bar-clip system (n 16). The masticatory performance test was carried out using 'Optocal' after forty chewing strokes. Nutritional condition was evaluated by means of a Mini-Nutritional-Assessment questionnaire. No individual was classified as malnourished. The masticatory performance test demonstrated a statistically significant difference before conversion (baseline) and 3 and 6 months after conversion of the lower conventional complete denture to an implant-retained overdenture (paired-samples t test; P < 0·05). A statistically significant difference before and after 6 months of conversion for nutritional condition (Wilcoxon test; P < 0·05) was also observed. The association between masticatory performance and nutritional assessment demonstrated that a statistically significant difference between masticatory performance of the subgroups classified at baseline as nourished (22·43 %) and those at risk of malnutrition (3·9 %) was only evidenced before conversion (P = 0·006). After the conversion from a lower conventional complete denture to an implant-retained overdenture, at 3 months, the risk of malnutrition and nourished at baseline did not present significant differences in masticatory performance. Nonetheless, the mean masticatory performance potential was 19·86 and 31·98 % for subgroups classified at baseline as at risk of malnutrition and nourished, respectively (P = 0·187). The results before conversion were less favourable for masticatory performance and nutritional condition. The increased retention of the mandibular prosthesis allowed improvement in masticatory performance and nutritional condition.

Interventions for replacing missing teeth: horizontal and vertical bone augmentation techniques for dental implant treatment

BACKGROUND

Dental implants require sufficient bone to be adequately stabilised. For some patients implant treatment would not be an option without horizontal or vertical bone augmentation. A variety of materials and surgical techniques are available for bone augmentation.

OBJECTIVES

To test whether and when augmentation procedures are necessary and which is the most effective technique for horizontal and vertical bone augmentation.

SEARCH STRATEGY

The Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and EMBASE were searched. Several dental journals were handsearched. The bibliographies of review articles were checked, and personal references were searched. More than 55 implant manufacturing companies were also contacted. Last electronic search was conducted on 11 June 2009.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of different techniques and materials for augmenting bone horizontally or vertically or both for implant treatment reporting the outcome of implant therapy at least to abutment connection. Trials were divided into two broad categories: horizontal augmentation and vertical augmentation techniques.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted independently and in duplicate. Authors were contacted for any missing information. Results were expressed as random-effects models using mean differences for continuous outcomes and odd ratios for dichotomous outcomes with 95% confidence intervals. The statistical unit of the analysis was the patient.

MAIN RESULTS

Thirteen RCTs out of 18 potentially eligible trials were suitable for inclusion. Three RCTs (106 patients) dealt with horizontal and 10 trials (218 patients) with vertical augmentation. Since different techniques were evaluated in different trials, only one meta-analysis could be performed. When comparing whether vertical augmentation procedures are advantageous over short implants, a meta-analysis of two trials resulted in more implant failures odds ratio (OR) = 5.74 (95% confidence interval (CI) 0.92 to 35.82; borderline significance, P = 0.06) and statistically more complications OR = 4.97 (95% CI 1.10 to 22.40) in the vertically augmented group. When comparing various horizontal augmentation techniques (three trials) no statistically significant differences were observed. When comparing various vertical bone augmentation techniques (eight trials) no statistically significant differences were observed with the exception of three trials which showed that more vertical bone gain could be obtained with osteodistraction than with inlay autogenous grafts (mean difference 3.25 mm; 95% CI 1.66 to 4.84), and with a bone substitute rather than autogenous bone in guided bone regeneration (mean difference 0.60 mm; 95% CI 0.21 to 0.99) in posterior atrophic mandibles, and that patients preferred a bone substitute block than a block of autogenous bone taken from the iliac crest (OR = 0.03; 95% CI 0.00 to 0.64; P = 0.02).

AUTHORS' CONCLUSIONS

These conclusions are based on few trials including few patients, sometimes having short follow-up, and often being judged to be at high risk of bias. Various techniques can augment bone horizontally and vertically, but it is unclear which are the most efficient. Short implants appear to be a better alternative to vertical bone grafting of resorbed mandibles. Complications, especially for vertical augmentation, are common. Some bone substitutes could be a preferable alternative to autogenous bone. Osteodistraction osteogenesis allows for more vertical bone augmentation than other techniques which on the other hand can allow for horizontal augmentation at the same time. Titanium screws may be preferable to resorbable screws to fixate onlay bone grafts.

Impact of implant support for mandibular dentures on satisfaction, oral and general health-related quality of life: a meta-analysis of randomized-controlled trials

OBJECTIVES

The aim of this study was to examine systematically the data published on the efficacy of mandibular implant-retained overdentures from the patient's perspective.

MATERIAL AND METHODS

Medline, Embase, The Cochrane Central Register of Controlled Trials and The Cochrane Systematic Reviews Database were searched and complemented by hand searching. All randomized-controlled trials published in English or French up to April 2007 were included, in which conventional dentures and mandibular implant overdentures in adult edentulous individuals were compared. The outcomes of interest were patient satisfaction, oral and general health-related quality of life. Random effects models were used to pool the effect sizes (ES) of all included studies.

RESULTS

Ten publications of seven randomized-controlled trials were identified and eight were included in the meta-analysis. When compared with mandibular conventional dentures, implant overdentures were rated to be more satisfactory at a clinically relevant level [pooled ES 0.80, z=3.56, 95% confidence intervals (CI) 0.36-1.24, P=0.0004], but a statistical heterogeneity was found (chi(2)=31.63, df=5, P<0.00001, I(2)=84%). The pooled ES for oral health quality of life was -0.41 (z=1.31, 95% CI, -1.02 to 0.20; P=0.19, chi(2)=11.53, df=2, P<0.003, I(2)=83%). There was a lack of evidence to show the impact of mandibular implant overdenture on perceived general health.

CONCLUSIONS

Our findings suggest that, although mandibular implant-retained overdentures may be more satisfying for edentulous patients than new conventional dentures, the magnitude of the effect is still uncertain. There is a need for additional evidence including cost-effectiveness analyses on the impact of mandibular implant overdentures and conventional dentures.

Interventions for replacing missing teeth: bone augmentation techniques for dental implant treatment

BACKGROUND

Dental implants require sufficient bone to be adequately stabilised. For some patients implant treatment would not be an option without bone augmentation. A variety of materials and surgical techniques are available for bone augmentation.

OBJECTIVES

General objectives: To test the null hypothesis of no difference in the success, function, morbidity and patient satisfaction between different bone augmentation techniques for dental implant treatment.

SPECIFIC OBJECTIVES

(A) to test whether and when augmentation procedures are necessary; (B) to test which is the most effective augmentation technique for specific clinical indications. Trials were divided into three broad categories according to different indications for the bone augmentation techniques: (1) major vertical or horizontal bone augmentation or both; (2) implants placed in extraction sockets; (3) fenestrated implants.

SEARCH STRATEGY

The Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE were searched. Several dental journals were handsearched. The bibliographies of review articles were checked, and personal references were searched. More than 55 implant manufacturing companies were also contacted. Last electronic search was conducted on 9th January 2008.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of different techniques and materials for augmenting bone for implant treatment reporting the outcome of implant therapy at least to abutment connection.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted independently and in duplicate. Authors were contacted for any missing information. Results were expressed as random-effects models using mean differences for continuous outcomes and odd ratios for dichotomous outcomes with 95% confidence intervals. The statistical unit of the analysis was the patient.

MAIN RESULTS

Seventeen RCTs out of 40 potentially eligible trials reporting the outcome of 455 patients were suitable for inclusion. Since different techniques were evaluated in different trials, no meta-analysis could be performed. Ten trials evaluated different techniques for vertical or horizontal bone augmentation or both. Four trials evaluated different techniques of bone grafting for implants placed in extraction sockets and three trials evaluated different techniques to treat bone dehiscence or fenestrations around implants.

AUTHORS' CONCLUSIONS

Major bone grafting procedures of resorbed mandibles may not be justified. Bone substitutes (Bio-Oss or Cerasorb) may replace autogenous bone for sinus lift procedures of atrophic maxillary sinuses. Various techniques can augment bone horizontally and vertically, but it is unclear which is the most efficient. It is unclear whether augmentation procedures at immediate single implants placed in fresh extraction sockets are needed, and which is the most effective augmentation procedure, however, sites treated with barrier plus Bio-Oss showed a higher position of the gingival margin when compared to sites treated with barriers alone. Non-resorbable barriers at fenestrated implants regenerated more bone than no barriers, however it remains unclear whether such bone is of benefit to the patient. It is unclear which is the most effective technique for augmenting bone around fenestrated implants. Bone morphogenetic proteins may enhance bone formation around implants grafted with Bio-Oss. Titanium may be preferable to resorbable screws to fixate onlay bone grafts. The use of particulate autogenous bone from intraoral locations, also taken with dedicated aspirators, might be associated with an increased risk of infective complications. These findings are based on few trials including few patients, sometimes having short follow up, and often being judged to be at high risk of bias.