Biomedical subjects

M E Geertman

Publications and source records attributed to M E Geertman.

At least 19 recordsLinked to original sources

PubMed2002

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

The purpose of this multicentre randomized clinical trial was to analyse surgical and prosthetic aftercare and clinical implant performance of edentulous patients with implant-retained mandibular overdentures and of patients with conventional dentures, either or not after pre-prosthetic vestibuloplasty and deepening of the floor of the mouth. The evaluation period was 5 years. The implant systems evaluated were the IMZ implant system, the Brånemark implant system and the Transmandibular Implant system. The centre in Groningen had five groups (n=149) and the centre in Nijmegen had three groups (n=86). The evaluation comprised of surgical and prosthetic aftercare, together with clinical implant performance (CIP). The highest implant loss (29%) is found in the Transmandibular Implant group. All groups had prosthetic revisions and complications according to the CIP-scale. The majority of the patients in the endosseous implant groups were subject to minor complications. The CIP-score of the Transmandibular Implant group is significantly higher than the scores of the other groups, because of the high number of lost posts. In 26;1% of the patients in this group score 4 is given, which means failure of the implant system. From this study it can be concluded that the endosseous implant systems used in this study have less surgical aftercare and a better clinical implant performance than the Transmandibular Implant system and are therefore the systems of choice for the edentulous mandible.

Aftercare↗

PubMed2002

[Implant-retained overdentures compared with complete dentures with or without preprosthetic surgery. Satisfaction and subjective chewing capabilities].

The aim of this prospective randomized clinical trial was to evaluate and compare a set of clinical items and satisfaction of a group of edentulous patients during a 5-year follow-up. They were treated according to one of the following modalities: 61 patients with a mandibular overdenture on two implants (IMP-group), 60 patients with a conventional complete denture (VP-group) and 28 patients with a complete denture after preprosthetic surgery (MVP-group). It can be concluded that endosseous implants, serving as retention for a mandibular overdenture, have a high survival rate after 5 years of follow-up (93%). The mean satisfaction score of the VP-group was lower than of the IMP-group. The mean satisfaction score of the MVP-group is lower than of the IMP-group.

Dental Implantation, Endosseous↗

PubMed2001

Implant-retained mandibular overdentures: 6-year results of a multicenter clinical trial on 3 different implant systems.

PURPOSE: The goal of this multicenter prospective clinical trial was to compare clinical outcome and post-treatment care and patient satisfaction with different implant systems used for mandibular overdenture treatment during a 6-year follow-up period. PATIENTS AND METHODS: A total of 87 edentulous patients with a severely resorbed mandible (bone height, 8 to 15 mm) received treatment involving either 2 Intra Mobiele Zylinder implants (IMZ group, n = 41) (Friedrichsfeld AG, Mannheim, Germany), 2 Brånemark implants (Brå group, n = 17) (Nobel Biocare AB, Gothenburg, Sweden) or a Transmandibular Implant (TMI; Krijnen Medical, Beesd, The Netherlands) (TMI group, n = 29). The evaluation involved clinical parameters, radiographs, surgical and prosthetic post-treatment care, clinical implant performance (CIP scale), and patient satisfaction. RESULTS: After 6 years, there was a significant difference in the mean plaque index:the mean plaque index of the TMI group was significantly higher than that of the IMZ and Brå groups. Other clinical parameters showed no significant differences. The implant survival rate of 97.5% was noted in the IMZ group, 97.1% in the Brå group, and 72.0% in the TMI group. The CIP scale were significantly worse for the TMI group. CONCLUSION: It was concluded that the IMZ and the Brånemark implant systems have a better survival rate and clinical implant performance than the TMI system. Based on these data, these systems should be the choice for the edentulous mandible with a height between 8 and 15 mm.

Alveolar Bone Loss↗

PubMed2000

A controlled clinical trial of implant-retained mandibular overdentures; five-years' results of clinical aspects and aftercare of IMZ implants and Brånemark implants.

The aim of this prospective randomized controlled clinical trial was to evaluate a set of clinical items and prosthetic aftercare of edentulous patients with a mandibular overdenture retained by 2 IMZ implants or 2 Brånemark implants during a 5-years' 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 4 implants were lost during the 5-years' follow-up (survival rate: 93%). In the Brånemark group 9 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 was subject to frequent fracture or loosening. From this study can be concluded that there is no difference in clinical state, radiographical state, survival rate and clinical implant performance between the IMZ implant system and the Brånemark implant system supporting an overdenture on 2 implants after 5 years of follow-up.

Chi-Square Distribution↗

PubMed2000

Changes in the edentulous maxilla in persons wearing implant-retained mandibular overdentures.

STATEMENT OF PROBLEM: It has been suggested that risk for severe resorption in the anterior maxilla is increased in persons wearing mandibular implant-retained overdentures. However, little information is available about the changes in the edentulous maxilla after mandibular implant treatment. PURPOSE: This study determined the possible changes in the width of the maxillary residual ridge 6 years after receiving mandibular implant-supported or implant-mucosa-supported overdentures and evaluated the association between the anatomic changes and subjective complaints with maxillary complete dentures. METHODS AND MATERIAL: The subjects for this study (n = 55), enrolled among the participants of a prospective clinical trial, were randomly assigned into 3 groups treated with: (a) implant-supported overdentures on a transmandibular implant system (n = 21); (b) implant-mucosa-supported overdentures on 2 IMZ implants (n = 20); or (c) conventional complete dentures (n = 14). A lingual contact occlusion concept with anterior open bite was used for tooth arrangement in all subjects. Diagnostic casts were made at baseline, and again at the 6-year follow-up. Most prominent points perpendicular to the crest of residual ridge were located in the incisor, canine, and premolar regions, after which the width of the ridge was recorded at these points with a Boley gage. Subjects' opinions on their dentures were evaluated with a questionnaire. RESULTS: Significant reduction in the width of the ridge was found in all measurement areas (mean difference = 0.4 to 0.6 mm; P <.0001). However, changes were small and not associated with the type of prosthetic restoration in the mandible. In subjects with implant-mucosa-supported overdentures, complaint of loose maxillary denture correlated with the decrement of residual ridge width. CONCLUSION: The width of residual ridge decreases with time, despite the type of mandibular prosthetic restoration.

Aged↗

PubMed1999

Implant-retained mandibular overdentures compared with complete dentures; a 5-years' follow-up study of clinical aspects and patient satisfaction.

The aim of this prospective randomized controlled clinical trial was to evaluate and compare clinical aspects and satisfaction during the first year following treatment and consecutively the change in treatment during the next 4 years of follow-up. Patients were allocated to one of the following treatment modalities: an implant-retained overdenture (IRO-group, 2 endosseous implants, n = 61) or a complete denture (CD-group, n = 60). One year after placement of the denture, unsatisfied patients of the CD-group got the opportunity for a retreatment including an implant-retained overdenture. In the IRO-group 4 implants were lost during the first year and again 4 implants were lost during the next 4 years (survival rate: 93%). All patients could be re-operated successfully. In the CD-group 14 patients (23%) chose an implant-retained overdenture after 1 year. Patients of the IRO-group were significantly more satisfied than patients of the CD-group after 1 year (satisfaction score 8.3 versus 6.6, scale 1-10) and after 5 years (7.4 versus 6.4). From this study it can be concluded that endosseous implants have a high survival rate after 5-years' follow-up. Satisfaction score of the IRO-group is diminishing in time, probably because patients get used to an improved situation. After 5 years, the mean satisfaction score of the CD-group (including patients who got implants) was still lower than of the IRO-group, in spite of the opportunity to a retreatment and have implant-retained overdentures.

Alveolar Bone Loss↗

PubMed1999

Masticatory performance and chewing experience with implant-retained mandibular overdentures.

The relationship between masticatory performance and chewing experience has not yet been explored for patients with implant-retained overdentures. Although many relationships have been found between parameters of objective and subjective oral function, the structure of these relationships remain unclear. Therefore, we studied in a randomized clinical trial the relationship between the comminution of an artificial test food, i.e. masticatory performance, and the subjective chewing experience. The trial involved a comparison between two groups receiving implant treatment and one group receiving conventional complete dentures (CD). The implant treatment involved either a mainly implant-supported mandibular overdenture on a transmandibular implant (TMI) or an implant-tissue-supported mandibular overdenture on two IMZ implants (IMZ). Masticatory performance as well as chewing experience were substantially better for the implant-retained overdentures compared with the complete denture group. No significant differences emerged between the TMI and the IMZ group. A multiple regression analysis did not provide any comprehensibility in the relationship between masticatory performance and the variables of chewing experience. In the linear structural relation analysis (LISREL) no direct relationship was found between masticatory performance and functional complaints mandibular denture. The results show that an improvement in masticatory performance does not imply the same improvement in chewing experience and vice versa.

Adult↗

PubMed1998

Randomized prospective clinical trial of two implant systems for overdenture treatment: a comparison of the 2-year and 5-year results using the clinical implant performance scale.

In a prospective randomized clinical trial, edentulous patients were treated with dental implants and overdentures. The results of treatment with two IMZ implants connected by a Dolderbar, and a transmandibular implant (TMI) were compared. By using the clinical implant performance scale, the clinical and radiographic data were evaluated and compared after a two-year and five-year follow up. After the five-year follow up, significantly less problems and complications were recorded in the IMZ group than in the TMI group (Wilcoxon, P=0.03). When compared to the two-year follow up, there was, however, a gradual increase of scores on the clinical implant performance scale in the IMZ group, while in the TMI group only a slight increase was recorded.

Adult↗

PubMed1998

Bite forces with mandibular implant-retained overdentures.

Sensitivity or pain of the mucoperiosteum covering the mandibular edentulous ridge is often thought to limit bite forces in complete-denture wearers. Therefore, bite forces with mandibular implant-retained overdentures may depend on the degree of implant support. This study analyzed the effects of different degrees of support for the mandibular denture on bite forces measured four years after denture treatment as part of a randomized controlled clinical trial. All subjects had received new maxillary dentures and (1) mainly implant-borne overdentures on a transmandibular implant (TMI), (2) mucosa-borne overdentures on two cylindric permucosal IMZ implants, or (3) new conventional dentures in the mandible. Fifty-three women and 15 men (mean age, 59.1 yrs; range, 41 to 77) participated in this trial. Both unilateral and bilateral bite forces were recorded at different positions with a miniature strain gauge transducer and a mechanical bite fork, respectively. The subjects were asked to bite at three force levels. Results indicated that women had significantly lower maximum bite forces than men. Persons with mandibular implant-retained overdentures had significantly higher unilateral and bilateral maximum bite forces than complete-denture wearers. However, bite forces did not differ between the mainly implant-borne (TMI) and mucosa-implant-borne (IMZ) implant systems. Therefore, it appears that differences in support for the mandibular overdenture by dental implants are not reflected in bite force capabilities.

Adult↗

PubMed1998

[Comparison of dental implant systems for mandibular overdentures].

OBJECTIVE: To compare three implant systems in patients with severely resorbed mandibles 1 year after insertion of the mandibular denture. DESIGN: A prospective multicenter randomized clinical trial. SETTING: Centers at University of Nijmegen and Groningen. METHODS: Three different implant systems were used: the transmandibular implant, the IMZ and the Brånemark system. Treatment was assigned to 88 patients according to a balanced allocation method. Evaluation included clinical and radiographic parameters. A Clinical Implant Performance scale (CIP) was constructed based on all conceivable complications of the different implant systems. RESULTS: During the healing period 1 IMZ- and 1 BRA-implant were lost. One TMI was removed after functional loading. The results of the clinical and radiographic parameters and the CIP-scale showed no significant differences between the three implant systems. CONCLUSION: Taking the one year evaluation into account the three systems used did not differ in clinical and radiographic performance.

Dental Implantation, Endosseous↗

PubMed1998

[Overdenture prostheses on implants versus complete dentures].

OBJECTIVE: To establish the treatment outcome of implant retained overdentures (IRD) versus complete dentures (CD) in which the outcome assessment focuses on the patient's subjective evaluation ('denture-satisfaction and chewing ability'). DESIGN: A multicenter randomized clinical trial (prospective). SETTING: The department of Oral Function and Prosthetic Dentistry of the University of Nijmegen, the department of Oral and Maxillofacial Surgery of the University Hospital Nijmegen and the department of Oral and Maxillofacial Surgery and Maxillofacial Prosthodontics of the University Hospital Groningen. METHODS: In this study 151 patients with severely resorbed mandibles participated, treatment had been assigned according to a balanced allocation method. Denture satisfaction and chewing ability were assessed using questionnaires before and 1 year after treatment. RESULTS: Before treatment all patients were dissatisfied with their mandibular denture and they could hardly chew tough or had food. One year after treatment the IRD-group was satisfied with their mandibular denture, whereas only one third of the CD-group was satisfied. With respect to the chewing ability the IRO-group scored significantly better than the CD-group (p < or = 0.0001). CONCLUSION: For patients with a severely resorbed mandible, overdentures retained by dental implants appear to provide a more satisfactory solution to their denture-related problems.

Alveolar Bone Loss↗

PubMed1997

Construction of a clinical implant performance scale for implant systems with overdentures with the Delphi method.

STATEMENT OF PROBLEM: The success of an implant system is often judged on the survival rate of the separate implants. This does not give a complete view of the "real" success of a system. To make that possible the total clinical performance, surgical and prosthetic, has to be considered. PURPOSE: This study aimed to set up a clinical performance scale for different implant systems retaining mandibular overdentures. MATERIAL AND METHODS: All data regarding surgical and prosthetic complications incurred and treatment procedures needed after implant placement were collected from a group of 90 patients who were treated either with two root form implants connected with a bar and supporting a mandibular overdenture or with a transmandibular implant system that supported an overdenture. All items were scored into five categories on the scale, defined as the "clinical implant performance" scale. The Delphi method was applied to categorize each item. A panel of experts assessed the items. RESULTS: After three rounds there was complete consensus between the experts for 65% of the items for the root form implant systems, and for 87% of the items at least five out of six experts gave the same score. For 55% of the items for the transmandibular implants systems there was complete consensus, and for 85% of the items at least five out of six experts scored in the same way. CONCLUSIONS: The Delphi method provides a useful scale for evaluating the clinical performance of implant systems retaining mandibular overdentures. The presented scale makes it possible to compare the overall performance of different implant systems for overdentures.

Delphi Technique↗

PubMed1996

Clinical aspects of a multicenter clinical trial of implant-retained mandibular overdentures in patients with severely resorbed mandibles.

In a multicenter clinical trial treatment, the effects of overdentures on different implant systems in patients with severely resorbed mandibles were compared 1 year after the insertion of new dentures. The implant systems used were the transmandibular implant (TMI), the IMZ (IMZ), and the Brånemark system (BRA). Treatment was randomly assigned to 88 patients according to a balanced allocation method. Evaluation included peri-implant and radiographic parameters. According to the Delphi method a Clinical Implant Performance scale (CIP) was constructed based on all conceivable complications of the different implant systems. During the healing period, one IMZ and one BRA implant were lost, and one TMI implant was removed after functional loading. The results of the peri-implant and radiographic parameters and the CIP scale revealed no significant differences between the three implant systems.

Adult↗

PubMed1996

Transmandibular implant versus intramobile cylinder implants: a randomized, prospective clinical trial.

A randomized, controlled clinical trial was conducted to compare two different implant treatment modalities for edentulous patients with severely resorbed mandibles. In one modality (the IMZ group), two intramobile cylinder implants were placed, connected by a Dolder bar and provided with an overdenture, and in the other (the TMI group), a transmandibular implant with a triple bar and cantilever extensions was placed, likewise provided with an overdenture. The conditions of the overdentures, the peri-implant tissues, and the implants were evaluated. Orthopantomograms were taken for radiologic evaluation. An overall complication scale which took account of all aspects was devised to compare the results. The follow-up period was 2-4 years, with a mean follow-up of 3 years. The condition of dentures and oral hygiene aspects were comparable for both groups. The complication rate in the TMI group was significantly higher than that in the IMZ group. The scores on the complication scale resulted in a significant difference between the TMI and the IMZ groups (Wilcoxon, P = 0.0044).

Alveolar Bone Loss↗

PubMed1996

Two-center clinical trial of implant-retained mandibular overdentures versus complete dentures-chewing ability.

This study is a two-center clinical trial with the aim to assess the treatment effects of implant-retained mandibular overdentures versus conventional complete dentures. Treatment had been assigned according to a balanced allocation method. The following criteria were used to enhance the comparability of the treatment groups: age, gender, the edentulous period of the mandible, the number of previously made mandibular dentures, the number of years having worn the present mandibular denture and the symphyseal bone height. 151 patients with severely resorbed mandibles participated in the study, they were treated at two centers. Ninety-one patients received an implant-retained mandibular overdenture (IRO) and 60 patients a conventional complete denture (CD). Since some patients refused the allocated treatment the "Intention To Treat" principle was applied. This implies that patients are evaluated in the originally allocated treatment group regardless of the actual treatment they received. Patient's experiences were evaluated before treatment and 1 yr after insertion of the new dentures. Results before treatment showed that both treatment groups were comparable: they were dissatisfied with their mandibular denture and they could hardly chew tough or hard foods. One year after insertion of the new dentures the IRO-group was satisfied with their mandibular denture, whereas only one third of the CD-group was satisfied. With respect to the chewing ability the IRO-group scored significantly better than the CD-group(P<0.0001).

Adult↗

PubMed1995

Patient satisfaction with implant-retained mandibular overdentures. A comparison with new complete dentures not retained by implants--a multicentre randomized clinical trial.

OBJECTIVES: The aim of this study was to establish the treatment outcome of full denture treatment with or without implant support, in which the outcome assessment focuses on the patient's subjective evaluation ('denture-satisfaction'). DESIGN: A multicenter randomized clinical trial. SUBJECTS: Thirty-two men and 118 women (mean age 56 +/- 9, range 35-84 years) participated in the study. The mean height of the mandible was 13 +/- 2 mm, measured on a lateral cephalometric radiograph. The patients were randomly assigned to either a group treated with implant-retained mandibular overdentures and a new maxillary denture, or to a control group treated with a new set of complete dentures. MAIN OUTCOME MEASURES: Denture satisfaction was assessed using questionnaires focusing on denture-related complaints and 'a general satisfaction rate'. RESULTS: Based on the baseline data, from the 'denture complaints' questionnaire six interpretable factors could be extracted. One factor did not vary following treatment and was excluded from the outcome analysis. At the 1-year evaluation three out of five factors showed significantly better scores for the group treated with implants than for the control-group. The same was found for the general satisfaction rate. CONCLUSION: For patients with a severely resorbed mandible, overdentures retained by dental implants appear to provide a more satisfactory solution to their denture-related problems.

Adult↗

PubMed1995

[Masticatory performance with mandibular implant-retained overdentures].

It was investigated in a clinical trial whether the masticatory performance of complete-denture wearers depended on the support for their mandibular dentures by implants or mucosa. The trial involved the provision of a new maxillary denture and either a new conventional mandibular denture (mucosa-borne), a mandibular overdenture retained by two IMZ-implants (implant-mucosa-borne), or a mandibular overdenture on a transmandibular implant (TMI; mainly implant-borne). In comparison with mandibular implant-retained overdentures, subjects with conventional dentures needed 1.5 to 3.6 times more chewing strokes for an equivalent reduction in particle size. No differences in masticatory performance were found between subjects with IMZ-implants and those with TMI. This suggests that the increased stability of the mandibular denture with implants determines the wearer's masticatory performance, rather than the support by implants.

Adult↗

PubMed1994

Comminution of food with mandibular implant-retained overdentures.

When complete-denture wearers are treated with from four to six implants and mandibular implant-borne prostheses, masticatory performance improves. No significant improvement has been observed with two implants and implant-mucosa-borne overdentures, suggesting that the masticatory performance of edentulous subjects depends on the degree of support for their mandibular prostheses by implants or alveolar mucosa. To verify this hypothesis, we studied, in a randomized clinical trial, the comminution of an artificial test food during mastication. The trial involved the provision of a new maxillary denture and either a new conventional mandibular denture, a mandibular overdenture retained by two permucosal cylindric implants through a single bar-clip attachment, or a mandibular overdenture retained by a transmandibular implant through five clips on a triple-bar construction with cantilever extensions. In comparison with the subjects wearing mandibular implant-retained overdentures, the subjects with conventional complete dentures needed between 1.5 and 3.6 times more chewing strokes to achieve an equivalent reduction in particle size. No differences in masticatory performance and efficiency were found between the subjects who had received two permucosal cylindric implants and those who had received a transmandibular implant. The results suggest that the increased retention and stability of the mandibular denture, rather than the degree of support by implants or alveolar mucosa, determine the wearer's ability to comminute food during mastication.

Adult↗