Five years of aftercare of implant-retained mandibular overdentures and conventional dentures

Comparative clinical study of conventional dental implant and mini dental implant-retained mandibular overdenture: A 5- to 8-Year prospective clinical outcomes in a previous randomized clinical trial

AIM

To compare the long-term prospective clinical outcomes in a previous randomized controlled clinical trial (RCT) of 2 Mini Dental Implant (2MDI), 4 Mini Dental Implant (4MDI), and 2 Conventional Dental Implant (2CDI)-retained mandibular overdenture with follow-up between 5 to 8 years.

MATERIALS AND METHODS

Thirty-seven patients formerly participated in the Comparative Clinical Study of CDI and MDI for Mandibular Overdenture were requested for examination of clinical outcomes. A total of 104 implants were placed with mean follow-up periods 6.64 ± 0.60 years. In Group 1 (2MDI) and Group 2 (4MDI), implants were placed and immediately loaded with Equator® attachments to retained mandibular overdenture. In Group 3 (2CDI), implants were placed and delayed 3 months for denture loading with ball attachment. The success rate, survival rate, clinical implant performance scale (CIP scale), peri-implant tissue status, prosthetic complication, implant stability quotient (ISQ), marginal bone level change (MBLC), and patient satisfactions were analyzed.

RESULTS

After 5 to 8 years follow-up, the success rate in Groups 1, 2, and 3 were 90.91%, 93.33%, and 54.55%, respectively. The success rate in Group 3 was significantly lesser than Group 1 (p = 0.016) and Group 2 (p < 0.001). The survival rate in Groups 1, 2, and 3 was 100%, 96.67%, and 90.91%, respectively, and showed no significant differences. Mean ISQ reported no significant differences between groups. Mean MBLC were 0.57 ± 1.19 mm, 0.68 ± 0.90 mm, and 1.55 ± 1.60 mm in Groups 1, 2, and 3, respectively. Group 3 reported significantly greater mean MBLC than Group 1 (p = 0.016) and Group 2 (p = 0.011), but Groups 1 and 2 were not significantly differences. The overall patient satisfactions were reported as not significant differences between groups.

CONCLUDE

Two MDI-retained mandibular overdentures with immediate loaded protocol performed had favorable clinical outcomes, cost effectiveness, and overall patient satisfactions after 5 to 8 years follow-up.

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.

Longevity of complete dentures: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Patients and clinicians are aware of the efficacy and benefits of complete dentures, but evidence regarding their longevity is limited.

PURPOSE

The purpose of this systematic review was to examine the literature describing the longevity of complete dentures and to review variations in longevity by denture type and duration of follow-up.

MATERIAL AND METHODS

Four electronic databases were searched by using key terms: MEDLINE, CINAHL (EBSCO), Dentistry and Oral Sciences Databases, and The Cochrane Library. Studies meeting the inclusion criteria were reviewed according to an established protocol and data extracted. Reference lists of identified studies were examined. Risk of bias was assessed by using the AXIS tool. Weighted means and weighted standard deviations were calculated. Pooled complete denture failure proportions were estimated by using random effects models based on the DerSimonian and Laird method.

RESULTS

The search yielded 21 607 unique abstracts, of which 273 met the inclusion criteria. Assessment of the full-text articles reduced this number to 42. Of these, 24 studies were rated as having low risk of bias and 18 as very low. The weighted mean ±standard deviation longevity of maxillary complete dentures was 10.3 ±3.8 years, of mandibular dentures was 8.6 ±2.6 years, and of both maxillary and mandibular dentures was 10.8 ±4.7 years. The pooled failure proportion for complete dentures observed for 2 years or less was 0.05 (95% confidence interval [CI]: 0.00-0.10), 5 to 6 years was 0.12 (95% CI: 0.08-0.16), and 10 years or more was 0.41 (95% CI: 0.28-0.53).

CONCLUSIONS

Complete dentures, fabricated primarily in university settings, were found to have a weighted mean ±standard deviation longevity of 10.1 ±4.0 years. The failure rate of these prostheses increased with denture age, and the longevity of maxillary dentures was greater than that of mandibular dentures.

Cost-effectiveness of implant-supported dental prosthesis compared to conventional dental prosthesis

OBJECTIVE

To conduct a cost-effectiveness analysis of alternatives for rehabilitation treatment of mandibular edentulism in the context of the Brazilian Unified Health System (implant-supported total dental prosthesis versus conventional total dental prosthesis).

METHODS

A Markov model was developed to capture long-term clinical and economic outcomes. The model’s population was comprised of a hypothetical cohort of 1,000,000 patients, aged 55 years, with total mandibular edentulism and without medical contraindications for performing surgical procedures. The adopted analysis perspective was that of the Brazilian Unified Health System. Based on the proposed model, we calculated cost – in BRL, and effectiveness – measured by quality-adjusted prosthesis year (QAPY). The time horizon of the analysis was 20 years.

RESULTS

Considering a 5% discount in costs and effects, the incremental cost-effectiveness ratio of implant-supported total dental prostheses compared to conventional total dental prosthesis (BRL 464.22/QAPY) was lower than the willingness to pay threshold adopted in the model (BRL 3,050.00/QAPY).

CONCLUSIONS

The results of this economic analysis showed that the rehabilitation of mandibular edentulous patients by implant-supported total prosthesis is very cost-effective when compared to conventional complete prosthesis, considering the cost-effectiveness limits employed.

A 15-Year Comparative Prospective Study of Surgical and Prosthetic Care and Aftercare of Overdenture Treatment in the Atrophied Mandible: Augmentation Versus Nonaugmentation

BACKGROUND

Different treatment strategies for the atrophied mandible are described in literature. The need for long term care and aftercare for these strategies is sparsely described, however.

PURPOSE

To prospectively assess the need for prosthetic and surgical care and aftercare of two implant treatment strategies for the atrophied mandible.

MATERIALS AND METHODS

Forty edentulous elderly patients were randomly assigned according to a balanced allocation method to a treatment strategy: dental implants in combination with an augmentation procedure versus a nonaugmentation procedure. All surgical and prosthetic care and aftercare were scored from the first visit until 15 years after implant placement.

RESULTS

Twenty elderly patients completed the 15-year follow-up. As expected, the augmentation group needed significantly more surgical time than the nonaugmentation group (338 vs 145 minutes), but the need for prosthetic care and surgical/prosthetic aftercare was comparable. Implant survival was lower in augmented mandibles (88.7% vs 98.7%, p < .05). Aftercare mainly consisted of routine inspections; the need for prosthetic adjustments was minor. Surgical aftercare was hardly needed.

CONCLUSION

The only difference in the need for surgical and prosthetic (after) care was the extra time needed for performing augmentation surgery and the higher risk on implant loss in augmented mandibles. Otherwise, the need for care and aftercare was of the same magnitude. Thus, when applicable, nonaugmentation surgery is preferred as no general anesthesia is needed and the morbidity is low.

Pressure distribution of implant-supported removable partial dentures with stress-breaking attachments

PURPOSE

This in vitro study investigated the pressure distribution of the implant-supported removable partial dentures (RPDs) with the stress-breaking attachments under the occlusal force.

METHODS

The experimental model of bilateral missing premolars and molars was modified from a commercial simulation model. Five pressure sensors were embedded near the bilateral first molars, first premolars, and medio-lingual alveolar crest. Two implants were placed near the second molars, and they were connected to the denture base using the following conditions: complete separation between the denture base and implant with cover screws (CRPD), flexible connection with a stress-breaking ball (SBB) attachment, and rigid connection without stress breaking with healing caps (HC). The pressure at five different areas of the soft tissue and the displacement of the RPDs were simultaneously measured, loading up to 50 N. The coefficient of variation (CV) for each connection was calculated from all data of the pressure at five areas to evaluate the pressure distribution.

RESULTS

The pressure on medio-lingual alveolar crest and molars of the HC was less than SBB and CRPD. In contrast, the pressure on premolars of SBB was greater than for the HC and CRPD. The CV of SBB was less than that of HC and CRPD. Denture displacement of HC and SBB was less than for CRPD.

CONCLUSIONS

Within the in vitro limitations, precise denture settlements and pressure distribution under the denture base could be controlled using an SBB attachment. An SBB attachment might be able to protect the implant from harmful force.

Early versus late loading of unsplinted TiUnite surface implants supporting mandibular overdentures: a 2-year report from a prospective study

The aim of this study was to evaluate the clinical performance of the implants supporting mandibular overdentures, and to investigate the prosthodontic outcomes of the mandibular implant overdentures. Twenty edentulous patients participated in this study. Forty implants were placed in the canine areas of the mandibles of all patients using the 1-stage approach. New maxillary complete dentures and the mandibular implant overdentures were delivered to 10 patients in the test group 1 week after surgery, while new maxillary and mandibular complete prostheses were delivered to 10 patients in the control group. These conventional mandibular prostheses were converted to mandibular implant overdentures 3 months after surgery. No implants were lost neither in test nor in control group. The average ISQ values between the two groups were not statistically significant during 2 years (P > 0.05). The average marginal bone resorptions were 0.4 and 0.5 mm for the test and the control group after 2 years. The number of appointments required for the prosthodontic maintenance of the mandibular implant overdentures in the first year was higher than that in the second year, which was statistically significant(P < 0.001). The results of the study suggest that the 1-week early loading approach does not adversely influence the clinical performance of the implants supporting mandibular overdentures.

Bone density assessments of oral implant sites using computerized tomography

The type and architecture of bone are considered to affect its load-bearing capacity and it has been indicated that poorer quality bone is associated with higher implant failure rates. To date, bone classifications have only provided subjective methods for pre-operative assessment, which can be considered unreliable. The aim of this study was to evaluate variations of the bone density in designated endosseous implant sites using computerized tomography. One hundred and thirty-one designated implant sites in 72 patients were utilized. Computerized tomography results indicated that bone densities may vary markedly when different areas of a designated implant site are compared. It has been observed that a difference in the bone density exists for the four regions within the oral area, with the anterior mandible yielding mean density values of 944.9+/-207 Hounsfield units (HU)>anterior maxilla, 715.8+/-190 HU>posterior mandible, 674.3+/-227 HU>posterior maxilla and 455.1+/-122 HU. Computerized tomography may be a useful tool for determining the bone density of interest areas before implant placement, and this valuable information about the bone quality provides dental practitioners to make better treatment planning regarding the implant positions.

Assessment of correlation between computerized tomography values of the bone, and maximum torque and resonance frequency values at dental implant placement

The aim of this study was to determine the bone density in the designated implant sites using computerized tomography (CT), the fastening torque values of dental implants, and the implant stability values using resonance frequency analysis. Further aim was to evaluate a possible correlation between bone density, fastening torque and implant stability. Eighty-five patients were treated with 158 Brånemark System implants. CT machine was used for preoperative evaluation of the jawbone for each patient, and bone densities were recorded in Hounsfield units (HU). The fastening torque values of all implants were recorded with the OsseoCare equipment. Implant stability measurements were performed with the Osstell machine. The average bone density and fastening torque values were 751.4 +/- 256 HU and 39.7 +/- 7 Ncm for 158 implants. The average primary implant stability was 73.2 +/- 6 ISQ for seventy implants. Strong correlations were observed between the bone density, fastening torque and implant stability values of Brånemark System TiUnite MKIII implants at implant placement (P < 0.001). These results strengthen the hypothesis that it may be possible to predict and quantify initial implant stability and bone quality from pre-surgical CT diagnosis.

A comparison between insertion torque and resonance frequency in the assessment of torque capacity and primary stability of Brånemark system implants

The aim of this study was to determine primary stability and insertion torque of Brånemark System implants placed in the anterior mandible, and to evaluate a possible correlation between primary stability and insertion torque. Thirty edentulous patients were treated with 60 Brånemark System implants using a one-stage technique. The insertion torque values of all implants were recorded with the Osseocare equipment. Immediately after implant placement, each implant was connected to the transducer of an Osstell machine to measure the primary implant stability. The average insertion torque and resonance frequency values were 41.5 +/- 5.8 and 74.1 +/- 3.8 for 30 implants. The correlation between insertion torque and resonance frequency values indicated a statistical significance (P < 0.001). The difference between mean insertion torque values for female and male patients was statistically significant (P < 0.001). No significant difference (P > 0.05) was found between younger and older patients with mean insertion torque values of 43.1 +/- 4.7 and 40.1 +/- 6.5 respectively. The results of this study showed a strong correlation between the primary stability and insertion torque values of Brånemark System TiUnite MKIII implants at the time of implant placement.

Long-Term Evaluation of Hollow Screw and Hollow Cylinder Dental Implants: Clinical and Radiographic Results After 10 Years

BACKGROUND

In 1988, an implant manufacturer offered a new dental implant system, with a wide choice of hollow cylinder (HC) and hollow screw (HS) implants. The purpose of this retrospective study of HS and HC implants was to evaluate clinical and radiographic parameters of peri-implant tissue and to analyze surgical and prosthetic aftercare.

METHODS

A total of 89 HS and 26 HC implants in 38 edentulous patients were available for complete evaluation. The patients were treated with overdentures stabilized by two or four implants. The follow-up period was 10 years.

RESULTS

The results of the clinical evaluation showed a mean sulcus probing depth of 3.3+/-1.3 mm (range=2 to 10 mm). The mean radiographic bone loss was 2.2+/-2.1 mm (range=0.1 to 12.2 mm). One implant (HS) was removed during the osseointegration period. Three other implants (two HS and one HC) in three patients had to be removed after 10 years. The survival rate of the HS implant (96.6%) was comparable to the HC implant (96.1%). The success rate of the HS implant (93.3%) was slightly more favorable compared to the HC implant (88.5%). The HS and HC implants met the Albrektsson criteria of success.

CONCLUSIONS

HS and HC implants provide a stable base for long-term support of a mandibular overdenture. Furthermore, it is important to monitor peri-implant bone level by taking annual radiographs and measuring probing depth, especially after prolonged service.

A controlled clinical trial of implant-retained mandibular overdentures: 10 years' results of clinical aspects and aftercare of IMZ implants and Branemark implants

The aim of this prospective randomized controlled clinical trial was to evaluate the clinical outcomes and prosthetic aftercare of edentulous patients with a mandibular overdenture retained by two IMZ implants or two Brånemark implants during a 10-year period. Patients were allocated to the IMZ group (n=29) or the Brånemark group (n=32) by a computerized balancing method. In the IMZ group, four implants were lost during the 10-year follow-up (survival rate: 93%). In the Brånemark group, nine implants were lost (survival rate: 86%). All patients were re-operated successfully. Multiple prosthetic revisions were necessary in both groups; especially the precision attachment system in the overdenture (23% of the total number of revisions) and the denture base and teeth (26% of the total number of revisions) were subject to frequent fracture. From this study, it can be concluded that both the IMZ implant and the Brånemark implant systems supporting an overdenture are functioning well after 10 years of follow-up. There are no indications of a worsening of clinical or radiographical state after 10 years.