Maxillary anterior and mandibular posterior residual ridge resorption in patients wearing a mandibular implant-retained overdenture

Four locator attachments of mandibular implant-retained overdentures with two different distributions: A 10-year retrospective preliminary study of residual alveolar ridge changes

OBJECTIVES

There is little information on the long-term function of the four Locator attachment of the mandibular implant retained overdenture (OD), particularly with different distributions.

PURPOSE

To compare the effect of different four inter-foraminal implant distributions retaining a mandibular OD after 10 years of function on posterior mandibular ridge resorption (PMandRR), anterior maxillary ridge resorption (AMaxRR), and the amount of marginal bone loss (MBL) around all four implants.

MATERIALS AND METHODS

Twenty-two participants with total edentulism who had worn mandibular OVDs retained by four inter-foraminal implants for 10 years of functional life were selected for this study. They were divided into two groups based on implant distribution: Group I with a quadrilateral distribution (QD) of implants and Group II with a linear distribution (LD) of implants. PMandRR, AMaxRR, and MBL around implants were measured.

RESULTS

After 10 years of function, PMandRR was significantly higher in the LD group than in the QD group (p < 0.001*). There was no significant difference in AMaxRR between the QD and LD groups (p = 0.431). The QD group showed a significantly greater amount of MBL around dental implants when compared with the LD group (p = 0.002*).

CONCLUSIONS

The LD of implants demonstrates more PMandRR compared with the QD. The QD of implants demonstrates a greater amount of MBL around dental implants compared with the LD. Both implant distributions demonstrate the same effect on the AMaxRR. MBL around implants remained within normal accepted values after 10 years of function.

Effect of mandibular bone atrophy on maxillary and mandibular bone remodeling and quality of life with an implant-retained mandibular overdenture after 3 years

STATEMENT OF PROBLEM

The medium-term effect of an implant-retained mandibular overdenture on bone remodeling in the maxilla and posterior mandible of edentulous patients and the effects on quality of life have not been established.

PURPOSE

The purpose of this prospective observational clinical study was to evaluate the 3-year effects of implant-retained mandibular overdentures on oral-health-related quality of life (OHRQoL) and bone remodeling in different regions of the maxilla and mandible in participants with atrophic or nonatrophic mandibles.

MATERIAL AND METHODS

Twenty-six edentulous participants received 2 narrow-diameter implants in the anterior mandible. Mandibular bone atrophy was categorized from presurgical panoramic radiographs according to the Cawood and Howell criteria. OHRQoL was assessed by using the OHIP-EDENT questionnaire. Participants were evaluated annually for 3 years to measure the marginal bone loss and bone area of the posterior mandible, and the anterior and posterior regions of the maxilla were assessed annually through panoramic radiographs. The data were analyzed by using a mixed-effects linear regression to estimate time-dependent trends and a mixed-effect linear regression model to verify differences between groups. The Pearson correlation coefficients between bone variables and 3-year OHIP-EDENT outcomes were calculated.

RESULTS

In the third year, atrophic participants had a significantly lower marginal bone loss (0.02 mm) than nonatrophic participants (-0.39 mm) (P=.030). Differences were also found in the functional limitation (nonatrophic=1.82 ±1.75, atrophic participants=1.92 ±1.54; P=.018) and handicap domains (nonatrophic=0.36 ±0.54, atrophic participants=0.08 ±0.27; P=.003). For nonatrophic participants, comparisons between baseline and 3-year outcomes showed significant bone resorption as indicated by the area ratio in the anterior maxilla (P=.035), posterior maxilla (P=.022), and posterior mandible (P=.009). Conversely, the bone area of the anterior maxilla (P=.019) decreased in atrophic participants between baseline and year 1, while the bone area of the anterior maxilla and posterior mandible increased (P<.001) between years 1 and 3. Higher effect sizes were observed in the OHRQoL domains of the atrophic participants.

CONCLUSIONS

Bone atrophy influenced both the OHRQoL profile and bone remodeling profile in different regions of the mandible and maxilla in mandibular overdenture users. In atrophic participants, bone tissue in both jaws responded positively to overdenture use, with bone apposition after the first year and bone area preservation in the anterior maxilla, posterior mandible, and peri-implant regions after 3 years of follow-up.

Enhanced healing process of tooth sockets using strontium-doped TiO2

Prevention of residual ridge resorption is important for tooth socket healing in clinical treatment. As a well known biomaterial, titanium dioxide (TiO₂) has been reported to show desirable bone regeneration capability. On the other hand, strontium plays a role in maintaining normal function in organisms and balancing bone remodeling. Hence, we synthesized strontium-doped titanium dioxide mesoporous nanospheres functionalized with amino-group using diphenyl diisocyanate. After incorporation with segmented polyurethane, the obtained injectable SPU/Sr-TiO₂/MDI nanocomposite adhesive showed satisfactory antibacterial activity and cell nontoxicity. This nanocomposite was used for tooth socket healing, and greatly promoted the formation of new bone tissue in the tooth extraction socket.

Average rate of ridge resorption in denture treatment: A Systematic Review

Purpose To clarify the rate of posterior residual ridge resorption (PRRR) in different denture treatments and the factors that can affect PRRR.Study selection A bibliographical electronic search was conducted on MeSH, Web of Science, and Ovid databases. Hand searching was also conducted. Longitudinal studies recording the average rate of PRRR in the mandible were included. The effect size was calculated based on the mean rate of PRRR with standard deviation and group size. The random-effects analysis was used to perform meta-analyses across qualified studies.Results A total of 2245 eligible studies were collected from the MeSH, Web of Science, and Ovid databases and hand searching. In the end, 19 studies met the inclusion criteria and were extracted. The average rate of PRRR in different mandibular denture treatments was assessed in this systematic review. The mean combined effect size was -1.05 ± 0.5 (95% confidence interval [CI]: -3.18-1.08) between four-implant overdentures and two-implant overdentures. The combined effect size was -0.01 ± 0.22 (95% CI: -0.93-0.82) between complete dentures and two-implant overdentures. Body mass index, number of dentures used, denture wearing habit, impression technique, artificial tooth material, and peri-implant bone resorption showed no significant effect on the rate of PRRR. Gender, denture material, and relining frequency showed a significant effect on the rate of PRRR.Conclusions This review summarized different average rates of PRRR in mandibular denture treatments. Meta-analyses have reported that four-implant overdenture treatments can lower the rate of PRRR compared to two-implant overdenture treatments. However, there was no significant difference in the treatment effect between the complete denture and two-implant overdenture treatments.

Comparison of ridge resorption and patient satisfaction in single implant-supported mandibular overdentures with conventional complete dentures: A randomised pilot study

Purpose

To compare ridge resorption (RR) and patient satisfaction in single implant-supported mandibular overdentures (SIMO) with conventional complete dentures (CCD) over a period of one year.

Material and methods

This prospective, randomized trial enrolled 30 completely edentulous participants following inclusion and exclusion criteria. The study was completed by 28 participants. Rehabilitation of 14 participants was done by using SIMO (group I) and CCD (group C) each according to randomization chart. For both the groups, RR was computed in millimeters from residual ridge height measured by using orthopantogram at 6 months (T1), 9 months (T2), and 12 months (T3) at 3 anatomic locations: maxillary posterior (L1), maxillary anterior (L2), and mandibular posterior (L3). Patient satisfaction was evaluated by using Geriatric Oral Health Assessment Index Hindi version (GOHAI-Hi) at 1week and 12 months after denture delivery.

Results

At 12 months, minimum RR was observed at L2 of group I (0.62 ​± ​0.20 ​mm) and maximum RR was observed at L3 of group C (1.04 ​± ​0.15 ​mm). Comparison of ridge resorption between group I and group C was statistically significant at T3 (P ​= ​.001 for L1, P ​= ​.006 for L2, and P ​= ​.028 for L3). At T3, in group I, RR was more at L3 than L2 region (P ​= ​.011) and L1 region (P ​= ​.015). Statistically significant difference of GOHAI-Hi scores was observed between group I and group C at end of 12 months (P ​= ​.003).

Conclusions

SIMO cause less RR and higher patient satisfaction as compared to CCD and can be recommended with higher predictability of success than CCD.

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.

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.

"Combination Syndrome" in an Upper/Lower Implant Overdenture Patient: A Clinical Report

An upper/lower overdenture case, which presented with clinical entities commonly associated with the combination syndrome, is described. To the author's knowledge, this is the first documented case to illustrate such a particular association. The patient presented with an upper overdenture on 4 individual implants with attachments, without palatal coverage, opposing a lower bar overdenture on 4 implants, delivered more than 10 years before presentation. The patient complained about esthetics (poor display of upper teeth, excessive showing of lower teeth, and occlusal plane cant) and chewing. The anterior maxilla had severe bone loss, whereas the anterior mandible had a large amount of bone. Our retreatment included an upper overdenture with palatal coverage and a lower overdenture, both prostheses supported by individually attached implants. The article describes in detail the reasoning behind chosen retreatment, along with limitations and compromises.

Premaxilla Stress Distribution and Bone Resorption Induced by Implant Overdenture and Conventional Denture

PURPOSE

To relate the principal stress, strain, and total deformation in the premaxilla region beneath a complete denture to the pattern of premaxilla bone resorption when opposed by a conventional complete denture (CD) or by a two-implant-retained overdenture (IOD) using finite element analysis (FEA).

MATERIALS AND METHODS

Three-dimensional solid models of the maxilla, mucosa, and denture of a selected edentulous patient were created using Mimics and CATIA software. The FEA model was created and duplicated in ANSYS 16.0 to perform two simulations for the IOD and the CD models. The values of maximum stress and strain and total deformation were obtained and compared to the outcomes of premaxilla resorption from a parallel clinical study.

RESULTS

The maximum principal stress in the premaxilla in the IOD model ranged from 0.019 to 0.336 MPa, while it ranged from 0.011 to 0.193 MPa in the CD model. The maximum principal strain in the IOD model was 1.75 times greater than that in the CD model. Total deformation was 1.8 times higher in the IOD model. Greater bone resorption was observed in regions of higher stress, which were on the occlusal and buccal sides of the premaxilla residual ridge.

CONCLUSION

Stress, strain, and total deformation values present in the premaxilla area beneath a CD were approximately two times greater in a comparison between an opposing mandibular two-IOD and an opposing mandibular CD. The results were consistent with a parallel clinical study in which the rate of premaxilla bone resorption was almost three times greater in the IOD group.

Mandibular Implant Overdentures: Treatment and Medico-Legal Considerations

The concept of a two-implant overdenture as the minimum standard of care or first choice treatment for the edentulous mandible was first proposed in 2002 and has since been backed by an overwhelming body of evidence supporting greater patient satisfaction and improved quality of life. This article examines the implant overdenture concept and its various options and discusses best practice from both the patient's and a medico-legal standpoint.

Clips vs Resilient Liners Used With Bilateral Posterior Prefabricated Bars for Retaining Four Implant-Supported Mandibular Overdentures

The objective of this research was to clinically compare peri-implant tissue health of bar-clips vs silicone-resilient liners used with bilateral posterior bars for retaining 4 implant-supported mandibular overdentures. Thirty completely edentulous male patients (mean age, 65 years) were randomly assigned into 2 equal groups. Each patient received 4 implants in the canine and first molar regions of the mandible using a flapless surgical technique. Mandibular overdentures were immediately connected to the implants with bilateral prefabricated instant adjusting bars. According to the method of retention to the bar, 1 group was retained with clips (GI), whereas the other group was retained with a silicone-resilient soft liner (GII). Peri-implant tissue health was evaluated clinically in terms of plaque scores (MPI), bleeding scores (MBI), probing depth (PD), and implant stability (IS). MPI, MBI, and PD were measured at mesial, distal, buccal, and lingual surfaces of each implant. Evaluations were performed 2 weeks (T0), 6 months (T6), and 12 months (T12) after overdenture insertion. Implants of GI with clips demonstrated significant increase in plaque, bleeding, and PD scores compared with those of GII with silicone-resilient liner at all observation times. Implants in GI demonstrated a significant decrease in implant stability compared with those of GII at T6 and T12 anteriorly and at T12 posteriorly. Resilient liners are considered better than bar-clips when used with bilateral posterior bars for retaining implant-supported mandibular overdentures in terms of peri-implant soft tissue health. Bilateral posterior ready-made bars cannot be proposed as a promising design for supporting implant-assisted mandibular overdentures.

Association between occlusal force distribution in implant overdenture prostheses and residual ridge resorption

This study aimed to investigate residual ridge resorption (RRR) of anterior and posterior maxillary and mandibular edentulous ridges, in patients treated with mandibular implant overdentures (IOD) and compare with conventional complete denture (CD) wearers, and to determine at each location, the association of RRR with the occlusal forces distribution and other patients' variables. The anterior and posterior RRR of IOD (six males, 17 females) and CD (12 males, 11 females) groups were determined using baseline and follow-up dental panaromic radiographs (DPT) (mean intervals 4 ± 1·8 years). The bone ratios were calculated using proportional area: anatomic to fixed reference areas and mean difference of ratios between the intervals determined RRR. The ridge locations included anterior and posterior maxillary and posterior mandibular arches. The T-Scan III digital occlusal system was used to record anterior and posterior percentage occlusal force (%OF) distributions. There were significant differences in anterior and posterior %OF between treatment groups. Two-way anova showed RRR was significant for arch locations (P = 0·005), treatment group (IOD versus CD) (P = 0·001), however, no significant interaction (P = 0·799). Multivariate regression analyses showed significant association between RRR and %OF at anterior maxilla (P = 0·000) and posterior mandible (P = 0·023) and for treatment groups at posterior maxilla (P = 0·033) and mandibular areas (P = 0·021). Resorption was observed in IOD compared to CD groups, with 8·5% chance of less resorption in former and 7·8% in the latter location. Depending on arch location, ridge resorption at various locations was associated with occlusal force distribution and/or treatment groups (implant prostheses or conventional complete dentures).

Effect of two designs of implant-supported overdentures on peri-implant and posterior mandibular bone resorptions: a 5-year prospective radiographic study

OBJECTIVES

The aim of this study was to evaluate and compare the effect of two designs of implant-supported overdentures on peri-implant and posterior mandibular bone resorptions after 5 years of follow-up.

MATERIALS AND METHODS

Twenty edentulous patients were randomly assigned into two equal groups: Group I (GI), patients received overdentures supported and retained by cantilevered bars on two canine implants and Group II (GII), patients received overdentures retained by straight bars on two canine implants and supported by two-first molar implants. Peri-implant vertical (VBL) and horizontal (HBLO) bone losses were assessed on periapical radiographs at the time of overdenture insertion (T0), 6 months (T6 m), 1 year (T1), 3 years (T3), and 5 years (T5) after insertion. Posterior mandibular bone resorption was evaluated using proportional measurements (posterior area index, PAI) made on panoramic radiographs at T0 and T5.

RESULTS

Group I recorded significant higher VBL than GII. VBL increased significantly with advance of time in both groups. Posterior implant recorded significant higher VBL than anterior implants in GII. HBLO did not differ significantly between groups or between observation times. Group I recorded significant higher PAI than GII at T5. Group, age, and initial height of the mandibular ridge were significantly correlated with PAI.

CONCLUSION

Within the limitations of this study, regarding the small sample size, it could be concluded that overdentures retained by straight bars on two canine implants and supported by two-first molar implants present a clinical advantage in terms of peri-implant and posterior mandibular bone preservation compared to overdentures supported and retained by cantilevered bars on two canine implants after 5 years.

Bone behavior in atrophic edentulous mandibles after rehabilitation with immediate loaded implant: a short-term radiographic and tomographic study

PURPOSE

To evaluate bone response in the posterior area of edentulous mandibles rehabilitated with fixed prosthesis supported on dental implants considering baseline severity of mandibular atrophy.

MATERIAL AND METHODS

The sample included 15 patients in whom 5 implants were inserted between the mental foramens. The prosthesis followed a cantilever extension from 15 to 20 mm. They were divided into 2 groups (severe and moderate) according to the degree of the atrophy presented. Panoramic x-ray and computerized tomography were obtained immediately after rehabilitation (T0) and after 8 months (T8). Linear measurements of the alveolar bone height at the posterior area of the mandible, 5, 10, and 15 mm from the long axis of the most distal implants, were recorded. Density measurements were also achieved at the same sites.

RESULTS

A slight bone increase in both groups was observed but with no statistically significant difference according to the baseline degree of atrophy.

CONCLUSIONS

There was slight qualitative and quantitative bone improvement in the posterior area of the mandibles with the use of immediately loaded implant-supported fixed prostheses during the observed period. These results suggest that long-term follow-up is very important to understand bone behavior after rehabilitation.

Posterior alveolar ridge resorption in bar-retained mandibular overdentures: 10-year results of a prospective clinical trial

OBJECTIVES

Data on posterior alveolar ridge resorption (PARR) in patients with two implant supported mandibular overdentures is very heterogeneous. The aim of this prospective study was to observe the PARR after ten years for a study population treated with a titanium bar retained overdenture on two IMZ-implants.

MATERIAL AND METHODS

The data pool consisted of digital and digitized conventional panoramic radiographs taken prior to implant placement and at follow up appointments. Digital measurements were carried out following an established procedure ("Tuebingen method" by Gomez-Roman). For each patient a linear regression was calculated resulting in a relative area related PARR-value per year. A simplified geometrical scenario was used for the estimation of absolute bone height losses.

RESULTS

Data of 23 patients was available. The mean observation period was 9.4 years (±2.4 years). An average area related PARR-rate of 1.02% per year was observed with high individual differences ranging from 0.15% and 2.63% per year. The estimated average ten year vertical bone loss in the chewing center was 1.5 mm.

CONCLUSIONS

Posterior bone resorption was found to be in the range previously reported for different implant restorations and therefore does not represent a particular problem of two implant bar retained overdentures. The results strengthen the two implant concept.

The influence of resilient liner and clip attachments for bar-implant-retained mandibular overdentures on opposing maxillary ridge. A 5-year randomised clinical trial

This study aimed to compare the influence of resilient liner and clip attachments for bar-implant-retained mandibular overdentures on opposing maxillary ridge after 5 years of denture wearing. Thirty edentulous male patients (mean age 62·5 years) received two implants in the anterior mandible after being allocated into two equal groups using balanced randomisation. After 3 months, implants were connected with resilient bars. New maxillary complete dentures were then constructed, and mandibular overdentures were retained to the bars with either clips (group I, GI) or silicone resilient liners (group II, GII). The prosthetic and soft tissue complications of the maxillary dentures were recorded 6 months (T6 m ), 1 year (T1), 3 years (T3) and 5 years (T5) after overdenture insertion. Traced rotational tomograms were used for measurements of maxillary alveolar bone loss. The proportional value between bone areas and areas of reference not subject to resorption was expressed as a ratio (R). Change in R immediately before (T0) and after 5 years (T5) of overdenture insertion was calculated. Maxillary denture relining times and frequency of flabby anterior maxillary ridge occurred significantly more often in GI compared with GII. The change of R in anterior part of maxilla was significantly higher than change of R in posterior part in both groups. GI showed significant resorption of anterior residual ridge compared with GII. Relining times and frequencies of flabby ridge were significantly correlated with change in R. Within the limitations of this study, resilient liner attachments for bar-implant-retained mandibular overdentures are associated with decreased resorption and flabbiness of maxillary anterior residual ridge and fewer maxillary denture relining times when compared with clip attachments.

Residual ridge atrophy in complete denture wearers and relationship with densitometric values of a cervical spine: a hierarchical regression analysis

BACKGROUND

The rate of residual ridge atrophy (RRR) and its association with mineral density of other bones have not yet been fully explained.

OBJECTIVE

To measure RRR over a 5-year period in complete denture wearers and relate it to the density of a cervical spine (CSBD).

MATERIALS AND METHODS

Sixty-two patients (different gender, age, body mass index, duration of edentulousness (DE) and different denture-wearing habits) participated. A copper stepwedge was attached to the cassette, and 50 lateral radiograms met the criteria to be included.

RESULTS

A significant decrease in vertical height was observed in all measured sites. The amount of RRR was highest in frontal areas of both jaws and decreased gradually towards lateral regions. Hierarchical regression analysis revealed that the amount of RRR in the maxillary frontal area could be explained up to 48.4% by the variable DE and only up to 6.1% by the CSBD, while gender had almost no influence (1%). Similar results were obtained for the lateral maxillary RRR (33.9%; 7%; 2%), frontal mandibular RRR (40; 8.4; 0.4%) and lateral mandibular RRR (31.5%; 3.4%; 7.7%).

CONCLUSION

Skeletal bone density, reflecting systemic and hereditary factors, is weakly related to RRR (3.4-8.4%).