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Biomedical subjects

A P Slagter

Publications and source records attributed to A P Slagter.

At least 19 recordsLinked to original sources
PubMed2006

Effect of postoperative radiotherapy on the functional result of implants placed during ablative surgery for oral cancer.

The purpose of this retrospective study was to evaluate the survival of dental implants placed during ablative surgery in the interforaminal region of the original edentulous mandible in patients with squamous cell carcinoma of the oral cavity in relation to postoperative radiotherapy. Forty-eight patients treated in 1996-2003 with surgery alone or in combination with postoperative radiotherapy were analysed. In all patients, 2 to 4 Brånemark Mk II/III 2-phase implants were placed during tumour resection. A total of 139 implants were placed of which 61 (21 patients) received postoperative radiotherapy: 60-68 Gy as a boost dose on the primary tumour site and 10-68 Gy on the symphyseal area. No difference was found in percentage of functional dentures on implants between the radiated and non-radiated groups. The success rate of osseointegration was 97% in the postoperative irradiated group and 100% in the non-irradiated group. The prosthetic success rate (75%) was lower because in 12 of the 48 patients (34 implants) a functional denture could not be fitted due to tumour recurrence or metastasis (7 patients, 22 implants) or for psychological reasons (4 patients, 12 implants), independent of whether radiotherapy was administered. Postoperative radiotherapy does not affect the osseointegration of dental implants placed during tumour ablation and the ultimate number of functional dentures. Primary implant placement in edentulous mandibles may have advantages over secondary implant placement in patients with oral squamous cell carcinoma.

Aged↗
PubMed2005

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

The objective of the present study was to analyse the effects of implant supported overdentures on masticatory function in patients with an extremely resorbed mandible, and to compare the masticatory function in these patients using three differing types of implant treatment protocols. The mandibular overdentures were retained by a transmandibular implant, by four endosseous implants following augmentation of the mandible, and by four short endosseous implants, respectively. Sixty patients (50 women, 10 men, mean age 59.4 years) were randomly allocated to one of the three treatment groups. Masticatory function was assessed before and after treatment using a questionnaire, a masticatory performance test, and a structured interview. The patient-based masticatory function improved significantly. Concerning these parameters there were no significant differences between the three groups before and after treatment. A significant difference existed between the three groups for the laboratory-assessed masticatory function before treatment, but after treatment this difference was no longer significant. From this study it can be concluded that patients with an extremely resorbed mandible and functional complaints of their lower denture report significant improvement in masticatory function after implant-overdenture treatment. Differences in masticatory function between the three studied modalities were not significant after treatment.

Aged↗
PubMed2001

Pain and instability during biting with mandibular implant-retained overdentures.

We tested in a randomized controlled clinical trial the effect of pain and instability of dentures on bite force with different degrees of mucosal support. The trial involved 3 groups who had received: 1) a new conventional denture (CD-group), 2) an implant-mucosa-borne overdenture on 2 IMZ implants (IMZ-group) or 3) a mainly implant-borne overdenture retained by a transmandibular implant (TMI-group). Fifty-three women and 15 men, mean age 59 years, participated in this study. Bite force measurements were made unilaterally with a transducer and bilaterally with a bite fork. After the measurements, subjects were asked whether or not biting had caused pain or tilting of one of the dentures. Significantly more complete-denture wearers reported pain. They reported more frequent pain in the mandible than in the maxilla (P < 0.001), whereas implant-groups seemed to experience more often pain in the maxilla. On the transducer, maxillary dentures of the CD-group tilted less (P < 0.01) and mandibular dentures more (P < 0.05) compared to the implant-groups. With the bite fork, tilting occurred more often in the incisal-cuspid area than in the molar region (P < 0.001). No effect of pain and tilting was observed on maximum bite force. It appears that oral implants used to stabilize mandibular dentures permit subjects to exert higher bite forces and reduce the pain as otherwise felt in the mandible during maximum biting. Due to this stabilization, pain and instability of the maxillary denture can become the limiting factor for a further increase in bite force.

Adult↗
PubMed2000

Biting and chewing in overdentures, full dentures, and natural dentitions.

It has been suggested that the provision of dental implants can improve the oral function of subjects with severely resorbed mandibles, possibly restoring function to the level experienced by satisfied wearers of conventional complete dentures. Nevertheless, a quantitative comparison has never been made and can be drawn from the literature only with difficulty, since studies differ greatly in methodology. To make such a comparison, we measured bite force and chewing efficiency by using identical methods in subjects with overdentures, complete full dentures, and natural dentitions. Our results indicated that bite forces achieved with overdentures on dental implants were between those achieved with artificial and natural dentitions. Chewing efficiency was significantly greater than that of subjects with full dentures (low mandible), but was still lower than that of subjects with full dentures (high mandible) and overdentures on bare roots. Differences in the height of the mandible revealed significant differences in chewing efficiency between the two full-denture groups. Furthermore, subjects with a shortened dental arch exerted bite forces similar to those of subjects with a complete-natural dentition, but their chewing efficiency was limited due to the reduced occlusal area. For all groups combined, a significant correlation was found between maximum bite force and chewing efficiency. Nearly half of the variation in chewing efficiency was explained by bite force alone.

Adult↗
PubMed2000

Rehabilitation of patients with severe (Class VI) maxillary resorption using Le Fort I osteotomy, interposed bone grafts and endosteal implants: 1-8 years follow-up on a two-stage procedure.

The 1 to 8 years follow-up results on a group of 15 patients who underwent a Le Fort I osteotomy with interposed bone grafts and who received implants at a second stage, are reported. The procedure proved to be extremely reliable in that sufficient bone was present for maximum size implants, whilst implant survival appeared to be high (94.6%). The forward advancement was stable and no discernible relapse occurred after prosthesis placement. All patients but one were highly satisfied with the aesthetic result and the rehabilitation of function.

Adult↗
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

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↗
PubMed1997

Professional hygiene care, adjustments and complications of mandibular implant-retained overdentures: a three-year retrospective study.

PURPOSE: This report presents a retrospective evaluation of postinsertion care required by 104 edentulous patients with advanced mandibular bone loss. MATERIAL AND METHODS: The patients were treated with new maxillary dentures and mandibular overdentures retained by two implants with a single bar-clip attachment. Distinction was made between professional hygiene care, adjustments, and treatment of complications. The follow-up period after insertion of dentures was 3 years for all patients. RESULTS: Approximately a third of the patients needed professional hygiene care. The need for adjustments declined during the years of function. Complications were encountered in approximately a third of the patients. The majority of these were not related to the implants, but to the superstructure and both the maxillary and mandibular dentures. CONCLUSIONS: Many edentulous patients with advanced mandibular bone loss who were treated with mandibular implant-retained overdentures need professional hygiene care, adjustments, and treatment of complications.

Bone Resorption↗
PubMed1997

Interposed bone grafts to accommodate endosteal implants for retaining mandibular overdentures. A 1-7 year follow-up study.

The results are reported on 34 edentulous patients, who underwent interposed autogenous bone graft augmentation in the symphysis of the mandible, combined with bone-hydroxylapatite onlay augmentation of the area posterior to the mental foramina. Two to four implants were placed in the grafted symphysis after 3-5 months. An overdenture was constructed three months later. The follow-up period ranged from one to seven years. An average loss of mandibular bone height of 10-13% was observed. The data provided no evidence of a further time-dependent resorption from two-and-half to seven years.

Adult↗
PubMed1997

[Surgical correction of the intermaxillary relation for placement of implants].

The loss of teeth is associated with alveolar bone resorption. Severe resorption of the maxillary alveolar process may cause persistent instability and loss of retention of the upper denture. Large intermaxillary discrepancies may complicate the treatment with implants to retain maxillary overdentures. Reconstructive surgical treatment methods that create sufficient bone volume for the placement of implants and at the same time normalize intermaxillary relationships, provide the basis for adequate oral rehabilitation.

Alveolar Bone Loss↗
PubMed1996

The state of dentition in relation to nutrition in elderly Europeans in the SENECA Study of 1993.

OBJECTIVE: To analyse the state of dentition and related aspects and to study their influence on the dietary intake of nutrients. DESIGN AND SUBJECTS: In the second cross-sectional measurement of SENECA's follow-up study, 12 research towns in 10 European countries and one town in Connecticut (USA) participated, involving 1424 elderly men and women born between 1913 and 1918. Dentition-related data were obtained from a general questionnaire; nutritional data were collected using a standardized modified dietary history. RESULTS: A large variation in the dental state existed among the towns. Women were more often edentulous and had fewer teeth. Self-reported chewing difficulties varied enormously. Most complaints were found in: women, edentulous subjects without dentures and in the towns in Spain, Portugal and Poland. More dentate women reported having visited their dentist. In the edentulous groups, differences between towns were small; for the dentate groups the percentage of dental visits varied from 0 in Coimbra (Portugal) to 96 in Mansfield (Connecticut/USA). For the edentulous subjects without any prosthetic supply, intakes of carbohydrate and vitamin B6 were significantly reduced. Also intakes of vitamin B1, vitamin C, dietary fibre, calcium and iron tended to be lower in this group. Town-dentition interactions existed for most nutrients. CONCLUSIONS: Substantial differences existed between towns in the influence of dentition on dietary intake.

Aged↗
PubMed1995

[Chewing with shortened dental arches].

Masticatory performance as measured with (objective) chewing tests is correlated with the number of teeth (the food platform area). In general, however, the masticatory ability (the subjective chewing experience) is sufficient as long as 20 or more 'well-distributed' teeth remain, such as is the case with an SDA, when the anterior teeth and the premolar teeth are present. Research indicates that an SDA does not lead to altered food selection. Studies have shown that a free-end removable partial denture generally does not improve the oral function in terms of masticatory ability or chewing comfort, unless in case of extreme shortened dental arches with only the anterior teeth present.

Dental Arch↗
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↗
PubMed1993

Human jaw-elevator muscle activity and food comminution in the dentate and edentulous state.

Masseter and temporal surface electromyograms were obtained from seven dentate subjects and six complete-denture wearers during mastication, maximal voluntary clenching and measurements of bite force. The participants chewed two artificial test foods with different textures. The dentate subjects comminuted both foods much better than the denture wearers. In both groups, the softer food was comminuted better than the firmer food. The differences in particle-size reduction originated largely from differences in the numbers of particles fragmented per chewing stroke. The rhythm of mandibular movement was unaffected by food texture and dental state. No significant differences in the duration of bursts of electric muscle activity were found between either group. Peak amplitudes of activity during mastication and maximal voluntary clenching were more than twice as large in the dentate subjects as in the denture wearers. In both groups, chewing the softer food was associated with lower peaks of activity than with the firmer food. The peak amplitudes were weakly related to the reduction in particle size. In both groups, the peak forces determined from electromyographic activity were larger than the estimated forces required for fragmenting the particles between the teeth.

Adult↗
PubMed1993

Comminution of two artificial test foods by dentate and edentulous subjects.

An experimental artificial test food with low fracture strength (Optocal) was compared with Optosil with respect to the comminution during mastication by complete denture wearers and subjects with natural dentitions. The comminution of both test foods revealed large differences between the denture wearers and the dentate subjects. These differences were larger with Optosil than with Optocal. The differences in comminution between Optocal and Optosil were larger in the denture wearers than in the dentate subjects. The differences in comminution between the denture wearers and the dentate subjects as well as the differences in comminution between Optocal and Optosil within each group were largely established in less than 20 chewing strokes. The results indicate that differences in selection contributed substantially to the differences in comminution. Since Optocal appeared to be much easier to chew than Optosil, it may be preferred to Optosil for measuring masticatory performance in complete denture wearers.

Adult↗