Biomedical subjects

Arjan Vissink

Publications and source records attributed to Arjan Vissink.

28 records · Page 2Linked to original sources

PubMed2002

Comparison of radiosensitivity of rat parotid and submandibular glands after different radiation schedules.

BACKGROUND AND PURPOSE: To investigate the radiosensitivity of rat parotid and submandibular gland functioning after local single dose, conventional fractionated and accelerated fractionated irradiation. METHODS: The salivary glands of male albino Wistar rats were locally irradiated with a single dose (15 Gy) or a calculated (alpha/beta; 9.6) biological effective dose of fractionated irradiation equal to this, viz. conventional fractionation (32 Gy in 16 fractions of 2 Gy/day, five times/week) or accelerated fractionation (32 Gy in 16 fractions of 2 Gy, two fractions/day). Parotid and submandibular/sublingual saliva samples were collected by means of miniaturized Lashley cups before and up to 240 days after irradiation. Salivary flow rate, lag phase and amylase secretion were used as parameters for the assessment of salivary gland function. At the end of the experiments the animals were sacrificed and the glands processed for histopathological examination. RESULTS: Up to 120 days after irradiation no differences were observed between the glands or between the different irradiation schedules. Beyond 120 days, however, the parotid gland performed better in flow rate and lag phase after fractionated irradiation, when compared to the submandibular gland. The observed differences in function corresponded with the observed late histopathological changes. The parotid gland contained more acinar cells and had a higher gland weight. No differences were observed between both fractionation schedules on each gland. CONCLUSIONS: The main observation from this study is the higher radiosensitivity of the submandibular gland compared to the parotid gland for late effects after fractionated irradiation. This may have implications for the treatment planning in case of radiotherapy for head and neck cancer.

Animals↗

PubMed2002

Vertical distraction of the severely resorbed edentulous mandible: a clinical, histological and electron microscopic study of 10 treated cases.

The aim of this study was to evaluate the clinical and histomorphological results of distraction of the severely resorbed edentulous mandible. In a group of 10 edentulous patients suffering from insufficient retention of their mandibular denture related to a severely resorbed mandible, the anterior segment was augmented as a preimplant surgical procedure using the nonvoluminous Groningen Distraction Device (GDD). Two months after the last day of distraction, a bone biopsy was taken with a trephine, both distraction screws were replaced by endosseous implants and the guide screw was removed. The biopsies were examined by means of light microscopy (LM) and transmission electron microscopy (TEM). Radiographical and histomorphological examination of the biopsies revealed the presence of two cortical zones, one at each end of the biopsies, a poorly mineralized, fibrous interzone in the middle of the distraction gap, and two zones of mineralization between the central fibrous and the peripheral cortical zones. Formation of lamellar bone parallel to the distraction vector was clearly visible in the mineralization zone as well as signs of remodelling at the borderline between the native cortical bone and the generate. Clinical examination showed in all patients that the anterior segment distracted from the mandible body was sufficiently enlarged to enable insertion of endosseous implants with a length of at least 12 mm. One implant was lost during the healing phase, but was successfully replaced thereafter. Implant retained overdentures were fabricated 3 months after implantation. All patients have good function 11.2 +/- 4.3 months after the end of treatment. From this study it is concluded that the GDD has proven to be a reliable tool for augmentation of the anterior segment of a severely resorbed edentulous mandible enabling osseointegration of endosseous load-bearing implants.

Aged↗

PubMed2002

The value of Waters' projection for assessing maxillary sinus inflammatory disease.

OBJECTIVE: The significance of the Waters' projection for judging maxillary mucosal disease is, at the least, questionable. The aim of this study was to evaluate the diagnostic use of Waters' projection of the maxillary sinus with particular regard to sinus mucosal swelling as a consistent sign of maxillary sinusitis. STUDY DESIGN: Forty consecutive adult patients were referred to an ear, nose, and throat surgeon for pain in the region of the paranasal sinus, recurrent mucopurulent rhinorrhea, and nasal congestion or obstruction for at least 3 months without any response to conservative treatment. Both conventional radiographs (Waters' projection) and coronal and axial computed tomography (CT) scanning of the maxillary sinuses were recorded. The conventional radiographs and CT scans, all made within an hour, were blinded and assessed in random order by 2 independent well-trained observers with standard radiodiagnostic criteria for sinus mucosal swelling. Intraobserver and interobserver agreements were quantified by calculating Cohen's kappa. The diagnostic significance of the Waters' projection was assessed with the CT scan images as criterion standard by calculating sensitivity and specificity, positive predictive value, likelihood ratio, and diagnostic odds ratio. RESULTS: Cohen's kappa for the intraobserver agreement of Waters' examination was 0.96, and the intraobserver agreement for CT scanning was 0.92. The interobserver agreement for Waters' projection and CT scanning was 0.76 and 0.92, respectively. With CT scanning as criterion standard, the sensitivity and specificity of Waters' projections to detect maxillary sinus mucosal swelling were 83.3% and 69.2%, respectively. The positive predictive (diagnostic) value of Waters' projections was 83.3%, the positive likelihood ratio 2.7, and the diagnostic odds ratio 11.25. CONCLUSIONS: From this study it can be concluded that Waters' projections do not necessarily rule out the presence of maxillary sinus mucosal swelling. Additional examinations may be indicated, especially in patients with compromised sinus clearance.

Adult↗

PubMed2002

Parotid sialography for diagnosing Sjögren syndrome.

OBJECTIVE: Despite the availability of many new imaging procedures, sialography has, after decades of use, maintained its status as the imaging procedure of choice for evaluating the oral component of Sjögren syndrome (SS). In this study, the clinical value of sialography as a diagnostic tool in SS was explored by assessing its diagnostic accuracy, observer bias, and staging potential. METHODS: One hundred parotid sialograms were interpreted independently in a blinded fashion by 2 trained and 2 expert observers. Sialograms were derived from a group of consecutive patients referred for diagnostics of SS. Patients were categorized as SS and non-SS by the revised European classification criteria. RESULTS: Trained observers reached a sensitivity of 95 and a specificity of 33% for SS by sialogram, whereas expert observers reached a sensitivity of 87 and a specificity of 84%. There was only "fair" interobserver agreement between trained and expert observers, whereas both expert observers showed "good" agreement with one another, according to Cohen's kappa. Intraobserver agreement was "good" to "very good" for all observers. The 4 different gradations of sialectasia, ie, punctate, globular, cavitary, and destructive, showed a weak but significant correlation with the duration of oral symptoms. CONCLUSIONS: This study markedly shows that the diagnostic value of parotid sialography for diagnosing SS greatly depends on the skills of the observer, implying that sialography lacks general applicability as a diagnostic tool in SS and requires specific expertise. Nevertheless, given its potentially high sensitivity and specificity in diagnosing SS as well as its useful staging potential, sialography still has its use in the evaluation of the oral component of SS.

Adult↗

PubMed2002

Oral and ocular manifestations in Sjögren's syndrome.

OBJECTIVE: Little is known about the relationship between lachrymal and salivary gland involvement in Sjögren's syndrome (SS). It is also of interest to know which eye test contributes most to the diagnosis of SS. We investigated the performance of different tear tests and how these tests relate to common serologic and salivary tests in SS. METHODS: In patients suspected of SS, the tear breakup time and the tear mucus score were evaluated in addition to the routine tests. Eighty consecutive patients were included, categorized into primary SS (pSS), secondary SS (sSS), and negative for SS. RESULTS: The tear breakup time and mucus score both performed insufficiently in diagnosing SS, in contrast to the Rose Bengal score. In pSS and sSS patients, a clear correlation was noted between tear and saliva quality and secretion rate, and between the Rose Bengal score and parotid sialography. Increased Rose Bengal scores also correlated significantly with hyperglobulinemia and presence of SSB antibodies in serum, with duration of subjective eye dryness, and with decreased tear gland function. CONCLUSION: The Rose Bengal score remains the eye test of choice having the highest specificity for SS. Hyperglobulinemia and especially positive SSB serology may warrant close monitoring of the eyes, since these serum findings appear to relate to the severity of ocular surface damage. Theoretically, a positive evaluation of either the ocular or oral component, in addition to positive serology or histopathology, could be sufficient to diagnose the syndrome for clinical purposes.

Adult↗

PubMedDate not supplied

Microbiota around root-form endosseous implants: a review of the literature.

Although high success rates for root-form endosseous implants have been reported, failures occasionally occur, and these implants must be removed. At least 10% of the failures have been suggested to be the result of peri-implantitis. There is some evidence that periodontal pathogens, mainly those belonging to the group of gram-negative anaerobic rods, play a role in the etiology of peri-implantitis. This article provides an overview of the literature associated with common peri-implant microbiology and an assessment as to whether bacteria associated with periodontitis exert a possible risk for peri-implant tissue breakdown. The peri-implant area is colonized by a large variety of oral microbial complexes. The microflora of the oral cavity prior to implant placement determines the composition of the microflora in the peri-implant area. Implants involved in peri-implantitis are colonized with large amounts of gram-negative anaerobic bacteria, including Fusobacteria, spirochetes, Bacteroides forsythus, and "black-pigmented bacteria" such as Prevotella intermedia, Prevotella nigrescens, and Porphyromonas gingivalis. Also, Actinobacillus actinomycetemcomitans can be isolated from these lesions. Thus, the microflora of peri-implantitis lesions resembles that of adult or refractory periodontitis. However, the presence of periodontal pathogens does not always lead to a destructive process. Therefore, the etiologic role of specific microorganisms in implant failure related to infection is still not resolved. Controversy remains as to whether organisms recovered from the original microflora cause the failure (and if so to what extent) or merely result from the infection. Nevertheless, there is accumulating evidence that bacteria cause the disease, while the individual's genetic makeup and environmental influences determine the severity of the disease.

Dental Implantation, Endosseous↗

PubMedDate not supplied

Treatment for an endosseous implant migrated into the maxillary sinus not causing maxillary sinusitis: case report.

Placement of endosseous implants in the maxilla has been proven to be a reliable treatment modality. If there is lack of supporting bone, the placed implant may not have enough primary stability and may migrate into the maxillary sinus. Displaced implants must be removed. If there are no signs of maxillary sinusitis, augmentation of the resulting alveolar defect can be performed during the same procedure.

Alveolar Ridge Augmentation↗

PubMedDate not supplied

Oral rehabilitation with dental implants in oligodontia patients.

PURPOSE: The aim of this retrospective report was to evaluate the treatment outcome of oral rehabilitation with dental implants in oligodontia patients. MATERIALS AND METHODS: Thirteen oligodontia patients treated with dental implants were examined clinically and radiographically (follow-up 3 +/- 2 years, range 1 to 8 years). In addition, patient-mediated concerns of satisfaction, treatment experience, and level of impairment of oral functions were assessed with questionnaires. RESULTS: In general, all patients were satisfied with the implant treatment and experienced the treatment as nonaggravating. There was significant functional improvement, with an implant survival rate of 86% and 96% for the maxilla and mandible, respectively. CONCLUSION: Dental implants can play an important role in the oral rehabilitation of patients with oligodontia. Patients were generally satisfied with the overall treatment experience and reported significant functional improvement. Implant survival rate was comparable with previous reports.

Adolescent↗

PubMedDate not supplied

Correction of a malpositioned endosseous implant by a segmental osteotomy: a case report.

A mandibular overdenture supported by 2 or 4 endosseous implants has been proven to be a reliable treatment modality for patients suffering from conventional denture problems. However, fabrication of an implant-retained mesostructure to support an overdenture is not possible in all cases. Malpositioning of implants is a common cause of failure in such cases. A case is presented in which a ball attachment caused pain and severe swelling of the floor of the mouth because of the lingual inclination of an endosseous implant. The lingual inclination of the implant was corrected by a segmental osteotomy. Six weeks later, prosthodontic treatment began, and the resultant overdenture supported by a Dolder bar was quite acceptable for the patient.

Bone Plates↗

PubMedDate not supplied

Implant-retained mandibular overdentures versus conventional dentures: 10 years of care and aftercare.

PURPOSE: This 10-year prospective, randomized, clinical trial investigated the treatment outcome of edentulous patients treated with mandibular overdentures retained by 2 endosseous implants compared with conventional dentures in patients with or without vestibuloplasty. MATERIALS AND METHODS: One hundred fifty-one edentulous patients (5 groups) with a symphyseal mandibular bone height between 8 and 25 mm participated. Sixty-two patients were treated with an overdenture retained by 2 implants (groups 1 and 3), 59 patients were treated with a conventional denture (groups 2 and 5), and 30 patients were treated with a conventional denture after preprosthetic vestibuloplasty (group 4). Patients who received conventional dentures but preferred implants later on could undergo implant surgery after 1 year of their initial treatment, but were analyzed in their original group. The prosthetic and surgical care and aftercare were scored during a 10-year evaluation period. RESULTS: One hundred thirty-three patients completed the 10-year follow-up evaluations. Forty-four percent of patients treated with conventional dentures switched within 10 years to implant-retained overdentures, versus 16% of the patients who were treated with conventional dentures after vestibuloplasty. On average, a greater time investment and more treatment sessions were needed in patients treated with implant-retained overdentures compared to patients treated with conventional dentures. CONCLUSION: Patients treated with an implant-retained overdenture need more treatment interventions and treatment time than patients treated with conventional dentures.

Adult↗