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Biomedical subjects

C de Putter

Publications and source records attributed to C de Putter.

At least 19 recordsLinked to original sources
PubMed2001

[Clinical evaluation of the Biocomp-implant system. Results after 1,3 and 5 years in a general practice].

A population of 107 consecutive patients was treated with a new HA-coated, screw-type dental implant (n = 384 implants), the Biocomp implant. Treatment was performed in a general dental practice by one and the same dentist. The implants were utilized for various types of prosthetic constructions, sometimes in challenging conditions with respect to patient selection, jaw bone quantity and quality. A clinical and radiographical evaluation was performed after 1, 3 and 5 years. After 5 years, the chance on implant survival was 87.1% (standard error 3.4%). Implant loss occurred predominantly within the first 1.5 year after implant placement. Particularly short implants, placed in the atrofic maxilla, frequently failed. Biocomp implants that served as abutments for an overdenture in the edentulous mandible or as a single tooth replacement in the upper anterior region had an excellent prognosis.

Adolescent↗
PubMed2000

Reliability of some clinical parameters of evaluation in implant dentistry.

Clinical tests that are commonly used to evaluate tissues surrounding natural teeth are also used in implant dentistry. It is unclear if they are equally valid and reflect the condition of the bone surrounding an implant reliably. This study evaluates the use of a plaque index, a gingiva index, the assessment of a probing depth and the Periotest value and relates the findings to the image on a radiograph in 16 patients, involving 32 IMZ implants. All four clinical tests showed poor sensitivity and, in general, only fair specificity when observations from the image on the radiograph were interpreted as the 'golden standard' for the presence or absence of pathology adjacent to the implant. Frequently, based on any clinical parameter, disease was not diagnosed, while the radiograph did show pathological loss of bone at the bone-implant contact area. It is concluded that the aforementioned parameters are unreliable and unfit for clinical evaluation in implant dentistry. Radiographs are needed to evaluate critical marginal bone changes surrounding dental implants.

Adult↗
PubMed1998

Survival of cylindrical implants in composite grafted maxillary sinuses.

PURPOSE: This retrospective study investigated the survival of dental implants placed in the maxilla after composite grafting of the sinus and an average of 55 months of loading. PATIENTS AND METHODS: Maxillary sinuses of 88 patients were grafted with autogenous cancellous bone combined with dense hydroxyapatite particles. After an average healing period of 3.4 months, hydroxyapatite-coated titanium endosseous implants were placed. A total of 388 implants were placed in grafted sinus floors, and 82 were placed in onlay grafted nonsinus position in the canine region. The implants were loaded with overdentures and fixed bridges 4 months (mean) after implantation, with a follow-up for a mean of 55 months. RESULTS: The cumulative implant survival was calculated according to the Kaplan-Meier method. Implant survival from the time of loading was 89% in full reconstructed cases and 90% in partially edentulous cases. The overall cumulative implant survival rate, including the loss in the surgical stage, was 82%. CONCLUSION: Implant loss in composite grafted maxillae after 70 months of follow-up was similar to loss in nongrafted maxillae.

Adult↗
PubMed1998

Dental implants in the atrophic maxilla: measurements of patients' satisfaction and treatment experience.

Maxillary bone reconstruction in combination with placement of dental implants is a treatment modality reported since 1980 for patients suffering from maxillary atrophy and difficulties with wearing removable prosthesis. This study reports on patient experience and satisfaction among 88 consecutive patients concerning surgical and prosthetic aspects of their treatment. A questionnaire was used to gather the data. Patient satisfaction was measured on a scale from 1 to 5 (1 = bad/few, 5 = very good/much). The satisfaction index with regard to the total treatment was 4.1 +/- 0.9. A total of 90% of the patients responded that they would go through the treatment again or recommend the treatment to a friend if necessary. The post-operative pain index scored 2.6 +/- 1.2. The acceptation of the post-operative pain at the crista iliaca was 86.1% and of the maxilla 89.9%. It is concluded that the results of measurements of patient satisfaction after maxillary bone reconstruction in combination with placement of dental implants were acceptable.

Adult↗
PubMed1998

Densitometric measurements of the mandible: accuracy and validity of intraoral versus extraoral radiographical techniques in an in vitro study.

In this study a comparison is made between intraoral and extraoral radiographical techniques for quantitative measurements of bone density in the edentulous mandible. A phantom model, composed of a dry mandible surrounded by a soft tissue substitute was used. Radiographs were made of aluminium implants of known volumes. Intra- and extraorally placed reference wedges of aluminium or a combination of aluminium and plexiglas were used for the measurement of the aluminium volume of the above-mentioned implants and compared with the real volume. The IBAS image analysis system was used for image processing and measurements. A systematic deficit in the measured volume of 15 to 29% was found. This error was irrespective of the radiographical technique and indicates a constant underestimation of the aluminium volumes. The differential influence of the secondary radiation on the images of the jaw and the wedge is proposed to be a possible cause of this constant underestimation. The intraoral and extraoral techniques do not display significant statistical differences in the levels of validity or accuracy. Obtaining serial intraoral radiographs of adequate quality in the atrophic edentulous mandible can be problematic. It is concluded from this in vitro study that in these cases Oblique Lateral Cephalometric Radiographs may provide a valuable alternative for quantitative image analysis.

Absorptiometry, Photon↗
PubMed1998

[Reliability of some clinical parameters in implant dentistry].

OBJECTIVE: This study evaluates if clinical tests that are commonly used to evaluate tissues surrounding natural teeth are equally valid in clinical evaluation of dental implants. DESIGN: A retrospective clinical study. SETTING: Department of Oral and Maxillofacial Surgery, Prosthodontics and Special Dental Care of the University of Utrecht. METHOD: The use of a plaque index, a gingival index, probing depth measurements and the Periotest was evaluated by relating the findings to the image on a radiograph in 16 patients, involving 32 IMZ implants. RESULTS: The four clinical tests show poor sensitivity and in general only fair specificity. CONCLUSION: The parameters are unreliable and unfit for clinical evaluation in implant dentistry during regular recall visits. Radiographs are needed to evaluate the condition of a dental implant and to detect critical marginal bone changes surrounding dental implants at an early stage.

Dental Implants↗
PubMed1997

A nationwide evaluative study on implant-retained overdentures.

OBJECTIVES: In the Netherlands, dental implants have been included in the National Dental Insurance Scheme (NDIS) since 1989. Nowadays, out-of-pocket expenditure is low, making implant treatment financially feasible for a large group of edentulous, potential implant candidates. Treatment can be performed by both oral surgeons and general dentists. Results of implant treatment in the literature are usually obtained in academic and specialized centers. In contrast to this, the present study evaluates the quantitative and qualitative aspects of rehabilitation with oral implants in combination with an overdenture when applied on a nationwide scale. METHODS: For this purpose all patients (n = 5410) treated between January 1989 and July 1992 were extensively documented pre-operatively, implant patients (n = 429) were clinically investigated by two independent observers and the effect of treatment on denture complaints was assessed by means of a questionnaire (n = 460). RESULTS: Only a small proportion of the potential pool of implant candidates is actually being treated, to a constant number of approximately 2000 patients a year. The selected patients have major denture problems and have received relatively high levels of prosthetic care during the last decade. Clinical results are comparable to those reported in the literature, implant survival after 3 years for the lower jaw being 96.3% and for the upper jaw 70.4%. Oral hygiene was frequently considered suboptimal and seen in conjunction with marginal inflammation of the peri-implant mucosa. Subjective results were excellent, patients were quite satisfied with the improvements in the comfort and esthetics of their lower denture. CONCLUSIONS: Implant-overdenture treatment, within the guidelines and regulations set by the Dutch NDIS, is a safe and effective treatment alternative, in particular for the rehabilitation of the lower jaw.

Dental Health Surveys↗
PubMed1997

The combined use of endosteal implants and iliac crest onlay grafts in the severely atrophic mandible: a longitudinal study.

Thirteen patients, who received an onlay bone graft augmentation to their severely atrophic mandible in combination with a simultaneous implant insertion, were studied prospectively. A reproducible method that allowed for accurate assessment of graft resorption, consisting of lateral and oblique-lateral cephalometric radiographs in combination with an image analysis system, was used to assess the resorption rate in all patients and between subgroups of patients, according to selected patient and treatment characteristics. Thirty implants were placed, none of which were lost, and all patients expressed satisfaction after a mean observation period of 877 days. A mean resorption rate of 36% of the grafted bone height occurred, mainly during the first year and with some degree of individual variance. After three years the resorption had virtually stopped. No statistically significant differences between any of the subgroups of patients could be distinguished. Peri-implantitis was found around eight implants in seven patients. It is concluded that the described surgical technique should be used only if there are stringent indications.

Aged↗
PubMed1997

A comparative study of flexible (Polyactive) versus rigid (hydroxylapatite) permucosal dental implants. II. Histological aspects.

Of the many materials that are applied in dental implantology, most have a high Young's modulus. In the concept of osseointegration, which is generally preferred, chewing forces are therefore directly transmitted from rigid implant materials to the relatively flexible surrounding bone. Polyactive is an elastomeric polyethylene-oxide polybutylene-terephthalate (PEO:PBT) copolymer, with a low modulus of elasticity, that exhibits bone-bonding characteristics. Previous finite-element analysis emphasized the benefit of the application of flexible implant materials. To assess the validity of this finite element model, one dense and two porous types of flexible Polyactive permucosal dental implants and one rigid hydroxylapatite (HA) implant were clinically tested in a beagle dog study and were compared during 30 weeks of loading. In an earlier report, it was concluded that dense Polyactive implants function clinically adequately and resemble the mobility of natural teeth. In the current study, the amount of bone contact was quantitatively assessed. Polyactive implants showed a statistically significantly higher bone contact, as compared to the HA implants, probably due to a significant water uptake and a subsequent increase in the volume of the denser Polyactive. Morphological analysis, based on back-scatter electron microscopy and light microscopy, revealed little remodelling activity of the bone surrounding the Polyactive implants. Few remodelling lacunae were seen and de novo bone formation was rarely observed. At some locations, a continuity between calcification zones with the polymer surface and the surrounding interfacial bone was observed, indicating the occurrence of bone-bonding. Also, the bone surrounding the HA implants showed little remodelling activity, although large resorption lacunae were observed, in which HA particles were present. Based on the observations of this study, flexible bone bonding implants might be more capable of transferring stresses to the surrounding bone and are therefore promising alternatives to "routine' rigid implants.

Alveolar Process↗
PubMed1997

A comparative study of flexible (Polyactive) versus rigid (hydroxylapatite) permucosal dental implants. I. Clinical aspects.

Recently, an elastomeric polyethyleneoxide polybutylene-terephthalate (PEO:PBT) copolymer (Polyactive) was introduced, which exhibits bone-bonding characteristics. In contrast to ceramics, bioglass, titanium and other metals, PEO:PBT copolymers are flexible materials that could reduce undesirable peak stresses along the neck of a permucosal implant. The application of three types of Polyactive permucosal dental implants (one dense and two porous types) and one dense hydroxylapatite (HA) implant were clinically tested and compared during 30 weeks of loading in a dog experiment. With respect to the porous Polyactive implants, it was observed that the pore diameter had decreased to such an extent that optimal bone ingrowth was not achieved. Polyactive is known to expand due to water uptake, and, as a consequence, the sizes of the pores of the press-fit inserted implants had decreased to a large extent. This feature explained the high loss of the implants with the porous outer layer (6 out of 22). None of the dense Polyactive implants and only one of the HA implants were lost. Statistical analysis was performed solely on the dense Polyactive and the HA implants. At the lingual sites, plaque scores, gingiva indices, bleeding indices and corresponding pocket depths were statistically significantly lower for both implant types, when compared to the corresponding values at the buccal, mesial and distal sites, irrespective of the observation period. Differences between the dense Polyactive and the HA implants were not observed. A considerable difference in mobility was registered between the Polyactive and the hydroxylapatite implants, as measured by the Periotest. The dense Polyactive implants functioned adequately and had mobility resembling natural teeth. As such, these dense flexible materials showed a favourable clinical function and they seem promising for reducing undesired peak stresses when applied as a dental implant.

Analysis of Variance↗
PubMed1996

Polyactive as a bone-filler in a beagle dog model.

Calcification is a crucial step in the bone-bonding mechanism of PEO/PBT hydrogel copolymers (Polyactive, a new generation of bone-fillers. A beagle dog study was conducted to determine whether the preoperative presence of a calcium phosphate layer (precalcification) on a PEO/PBT 80/20 copolymer would further increase the bone-bonding rate. Standard bone cavities were filled with either precalcified or nonprecalcified porous cylindric PEO/PBT 80/20 implants, or hydroxyapatite granules held together with PEO/PBT 70/30, or were left unfilled. A significantly higher percentage of mineralized component was present in the cavities filled with the precalcified PEO/PBT 80/20 copolymer than in the control defects. As a result of swelling by fluid-uptake, the press-fit inserted copolymer implants showed a significant reduction in pore size, thus preventing optimal bone ingrowth. Both precalcification of the copolymer and underfilling of the defect, to create space for the copolymer to increase in diameter, stimulate postoperative calcification and bone ingrowth in PEO/PBT 80/20 copolymers.

Alveolectomy↗
PubMed1996

A clinical retrospective evaluation of FA/HA coated (Biocomp) dental implants. Results after 1 year.

In this retrospective clinical evaluation, the performance of loaded titanium implants with a bilayer bioactive surface coating of the relatively reactive hydroxylapatite (HA, outer layer) and the more stable fluorapatite (FA, inner layer) was evaluated. 98 consecutive patients were included in the study for a total of 354 implants, loaded by overdentures, fixed partial dentures and single tooth replacements. Statistical analyses revealed a cumulative probability of implant survival on a per patient basis of 94.5% (s.e. 2.7%), one year after implant installation. On implants that were lost parts of the bilayer FA/HA coating had vanished as a result of primary or secondary infection and subsequently epithelial down growth. Most complications were associated with implants placed in the maxilla. Periotest values (PTV) were generally high, indicating adequate osseointegration. The PTV's were statistically significantly less favorable in implants placed in the maxilla. The most favorable PTV's and gingival index scores were found around implants servicing overdentures. Marginal bone loss averaged approximately 2mm during the observation period. The amount of marginal bone loss corresponded with the distance from the neck of the implant to the first thread of the implant's cervical screw-section. It is concluded that, during the relatively short observation period, the FA/HA coated implants function adequately. However, in the absence of a direct implant-to-bone contact preceding implant loss, part of the FA/HA coating on the titanium implants generally dissolves.

Adult↗
PubMed1996

A single dimension statistical evaluation of predictors in implant-overdenture treatment.

This retrospective study aims to identify factors that contribute to either a poor or excellent treatment result in implant-overdenture treatment. A total of 375 implants, in an equal number of patients were included in the study. A clinical examination was performed by 2 observers. Gingival health and oral hygiene were assessed and additional complications were noted, including implant loss. 2 outcome variables, STATUS1 and STATUS2, were constructed that were different with respect to treatment outcome, representing a poor and an excellent result, respectively. Patient variables such as age, gender, medical status and prosthetic history were collected pre-operatively with a questionnaire. Life table analyses were used to test subsets of patient and treatment variables for differences in survival distribution, both for poor or excellent results. With regard to predictors of poor results; implants in the upper jaw were associated with a poorer outcome than those placed in the lower jaw (p = 0.01). When more than 2 implants were placed, the quality of survival was also impaired (p = 0.03). Interestingly, implants in patients with a self-proclaimed history of tooth loss due to periodontitis appear to have a far poorer treatment outcome than implants placed in patients without such a history (p = 0.01). No other variables could be related to a poor result after 3 years. None of the variables could predict an excellent treatment outcome.

Age Factors↗
PubMed1995

Delayed implants in the anterior maxilla with the IMZ-implant system: a radiographical evaluation.

One hundred and seventy-three IMZ-implants in 81 patients, placed in the anterior region of the maxilla, were evaluated radiographically by two observers. Radiographs were evaluated at three intervals, namely at the time of implant placement, the time of prosthetic restoration and at the latest available radiograph, on average 2 1/2 years after implant placement. In this study marginal bone height and the type of radiolucency adjacent to the implant were determined. Both observers were able to classify the marginal bone height (mesial and distal) and the distinctive type of resorptive defects to an acceptable level of agreement, with Cohen's kappa ranging between 0.48 and 0.69. It was found that, at the most recent visit to the clinic, angular-shaped resorptive defects are found mesially and/or distally of the implants at approximately 25% of the implants. At this stage 20.7% of the mesial implant sites and 27.9% of the distal implant sites show marginal bone heights less than three-quarters of the implant length. These findings do not fully underscore and sometimes even contradict the clinical observations which were considered highly satisfactory.

Alveolar Bone Loss↗
PubMed1995

The influence of a flexible coating on the bone stress around dental implants.

The influence of a three-layered flexible coating of Polyactive on bone stress distribution was investigated by three-dimensional finite element models of mandibular bone, in which a titanium implant (coated or uncoated) was located. Polyactive is a system of poly(ethylene oxide) poly(butylene terephthalate) segmented co-polymers with bone-bonding capacity. In the case of sagittal and transversal loading, the use of a Polyactive coating reduced both the minimum principal stress in the bone and the compressive radial stress at the bone-implant interface. However, it raised the maximum principal and the tensile radial stress. In the case of vertical loading, the application of a flexible coating reduced the compressive radial stress at the bone-implant interface around the neck of the implant by a factor of 6.6 and the tensile radial stress by a factor of 3.6. Variations in composition and thickness of the coating did not affect the results significantly.

Alveolar Process↗
PubMed1995

Observations of the bone activity adjacent to unloaded dental implants coated with Polyactive or HA.

In addition to bone-bonding biomaterials such as calcium phosphate ceramics and Bioglass/glass ceramics, an elastomeric poly(ethylene oxide) poly(butylene terephthalate) (PEO/PBT) segmented block co-polymer (Polyactive) was recently introduced. In contrast to ceramic biomaterials, Polyactive is a flexible material. In a previous three-dimensional finite element analysis study, it was stated that application of a flexible Polyactive coating simulates the function of the periodontal ligament. The topic of this investigation was to compare the bone-bonding capacity of Polyactive-coated titanium implants with hydroxylapatite (HA) coated implants. The implants were inserted bilaterally in the edentulous part of the mandibular bone of 12 goats. After 3 weeks, the implants were in close contact with the cortical bone, but no cortical bone reaction or remodelling was observed. After 9 weeks, an extensive bone reaction was seen around the HA and Polyactive-coated implants and contact was frequently encountered between newly formed bone and the implants. Within the surface of the Polyactive coating, a considerable amount of calcification was present. After 25 weeks, cortical remodelling was still apparent. A striking finding was the apparent association between osteon formation and calcification within the surface of the Polyactive layer. Back-scatter analysis of the non-decalcified Polyactive bone interface showed the presence of a calcium phosphate layer in the implant material that apparently formed a continuity with the mineral matrix of bone, suggesting bone-bonding. In general, it was observed that the bone reactions to HA and Polyactive were comparable. A swelling of the coating, just beneath the cortical layer (champagne-cork effect) was often seen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Characteristics of 5410 edentulous implant candidates and the treatment they receive.

Since 1989 implant dentistry in the Netherlands is a National Dental Insurance (NDI) benefit, thus reducing out-of-pocket expenditures for implant candidates considerably. A nationwide investigation was set up in order to evaluate quantitative, qualitative and financial effects of this new provision. The patient and treatment characteristics of 5410 edentulous implant candidates are discussed. Intensive monitoring of the usage of these new regulations facilitates health care policy making, including future planning. Over a 3 1/2 yr period, two out of every thousand totally edentulous NDI patients were treated in combination with dental implants. This number is being considered small, bearing in mind the number of edentulous patients in the Netherlands and the proportion of dissatisfied denture wearers. Demographic data, prosthetic and pre-prosthetic surgical history reveal that these patients, mostly female and middle-aged, experience severe denture-related problems. In the majority of cases the implants are placed by an oral surgeon and the suprastructure is made by a general dentist or at a centre for special dental care. The treatment itself mostly consists of an implant retained overdenture on two or four permucosal implants and a bar-construction.

Adolescent↗