Evaluation of the surface damage of dental implants caused by different surgical protocols: an in vitro study.

The implant surface must withstand high insertion torque during implant insertion. The aim of this study was to investigate the damage to implant surfaces caused by two different insertion protocols in vitro. Fifteen titanium implants per group were inserted in standardized polyurethane foam models, group 1 according to a non-threaded surgical protocol and group 2 according to a threaded surgical protocol. Before and after insertion, the surfaces were visualized by scanning electron microscopy (SEM) and non-contact laser profilometry. Different surface area parameters were evaluated and maximum torque during insertion was determined. SEM detected topographical changes such as deposition of the test block and smoothening of the surface in the region of the thread crests in both groups. The laser profilometry analysis revealed significant changes in the surface topography of the implants in both groups, but no differences between the groups. Insertion torque was significantly decreased in the threaded group. Both types of surgical intervention resulted in surface damage. Less damage was detected to the thread crests with the use of a thread cutter, and most of the surface was not visibly affected by the surgical protocol at the microscopic level. The surgical protocol seems to have a minor influence on preservation of the implant surface.

[Development and validation of the Mini Dental Assessment : A procedure for improved estimation of need for dental treatment in geriatrics]. / Entwicklung und Validierung des "Mini Dental Assessment" : Ein Verfahren zur besseren Einschätzung des zahnärztlichen Behandlungsbedarfes in der Geriatrie.

BACKGROUND: In the future there will be an increasing demand for professional care with simultaneous retention of the dentition in older people. Due to inadequate dental knowledge, it is often not possible for caregivers to adequately assess dental deficits. OBJECTIVE: The aim of the study was to develop and validate a simple tool (Mini Dental Assessment, MDA) to assess possible dental treatment needs (DTN) of residential geriatric facilities by nursing personnel. MATERIAL AND METHODS: In the study 169 patients (51 from the University Hospital Giessen, 118 from the Bonifatius Hospital Lingen) underwent a dental examination. The dental status was evaluated based on the California Dental Association (CDA) criteria and the DTN determined. In addition, the time since the patients last visit to a dentist (TLVD) and denture age (DA) were documented and a chewing function test (carrot eating test, CET) was carried out. In a second study 155 patients were examined (115 from the University Hospital Giessen, 40 from the Bonifatius Hospital Lingen) corresponding to the reference sample and including a further chewing function test (after Schimmel und Slavicek) and questionnaires on quality of life (Oral Health Impact Profile (OHIP), Denatl Impact on Daily Living (DiDDL)). RESULTS: A total of 108 patients required dental treatment. The mean value (±SD) for the TLVD was 2.5 ± 3.8 years and 10.8 ± 8.9 years for the DA. There was a positive correlation (Spearman, P < 0.005) between the DTN and degree of comminution in the CET (3.4 ± 1.8 grade). Based on the results an assessment tool was developed using the variables CET, TLVD and DA weighted by the respective regression coefficients (10:3:1). The resulting mean total MDA score was 51.32 ± 28.14. A sensitivity/specificity analysis was conducted and a receiver operating characteristic (ROC) curve calculated (area under curve, AUC: 0.805; 95% CI: 0.738-0.873). The ROC curve from the follow-up study showed a good agreement with the ROC curve from the reference study (AUC 0.829, 95% CI: 0.751-0.907). CONCLUSION: Based on the results of the study it could be shown that the MDA is a suitable instrument for making a valid statement on the assessment of DTN of patients in long-term care facilities. The validation study revealed the validity of the MDA in its originally developed form and the addition of two further chewing function tests did not significantly improve the validity of the MDA. Overall, the MDA appears to be an appropriate tool to help nursing home personnel to assess the necessity for nursing home residents to visit a dentist.

Mini dental assessment: a simple screening test for non-dental staff.

OBJECTIVE: The objective of this study was to develop a simple tool for the assessment of possible dental treatment needs (DTN) for non-dental professionals (Mini Dental Assessment, MDA). To keep the assessment universal, we aimed to base it on the patient's history and a simple chewing efficiency test (CET) as the dental status is a known determinant for chewing efficiency. MATERIALS & METHODS: The assessment was developed using data from 169 patients from two sites (University Hospital Giessen, St. Bonifatius Hospital Lingen, both Germany). In all patients, a dental examination was performed, the denture status was evaluated (based on the California Dental Association criteria; CDA criteria), and the DTN was determined. In addition, the time since the patient's last visit to a dentist (TLVD) and denture age (DA) were assessed. Furthermore, a CET was carried out and the comminution score was determined (CETS). RESULTS: In total, 108 patients required dental treatment. The mean value (±SD) was 2.9 ± 0.9 score points for the DTN, 2.5 ± 3.8 years for the TLVD, and 10.8 ± 8.9 years for the DA. There was a significant correlation (Spearman, P < .05) between the DTN and degree of comminution (3.4 ± 1.8). Based on the results of the statistical analysis, the intended assessment tool was developed using the variables CETS, TLVD, and DA weighed by their respective regression coefficients (10:3:1). Subsequently, the resulting MDA score (51.32 ± 28.14) was calculated. A sensitivity/specificity analysis was conducted and a receiver operating characteristic curve was calculated (SPSS 17.0, area under curve 0.805; 95 % CI 0.738-0.873). CONCLUSION: It can be concluded that the dental status of elderly patients is reflected in the outcome of the MDA. However, ongoing validation is needed. TRIAL REGISTRATION: DRKS00003219.

A new method for assessing the accuracy of full arch impressions in patients.

OBJECTIVE: To evaluate a new method of measuring the real deviation (trueness) of full arch impressions intraorally and to investigate the trueness of digital full arch impressions in comparison to a conventional impression procedure in clinical use. METHODS: Four metal spheres were fixed with composite using a metal application aid to the lower teeth of 50 test subjects as reference structures. One conventional impression (Impregum Penta Soft) with subsequent type-IV gypsum model casting (CI) and three different digital impressions were performed in the lower jaw of each test person with the following intraoral scanners: Sirona CEREC Omnicam (OC), 3M True Definition (TD), Heraeus Cara TRIOS (cT). The digital and conventional (gypsum) models were analyzed relative to the spheres. Linear distance and angle measurements between the spheres, as well as digital superimpositions of the spheres with the reference data set were executed. RESULTS: With regard to the distance measurements, CI showed the smallest deviations followed by intraoral scanners TD, cT and OC. A digital superimposition procedure yielded the same order for the outcomes: CI (15±4µm), TD (23±9µm), cT (37±14µm), OC (214±38µm). Angle measurements revealed the smallest deviation for TD (0.06°±0,07°) followed by CI (0.07°±0.07°), cT (0.13°±0.15°) and OC (0.28°±0.21°). CONCLUSION: The new measuring method is suitable for measuring the dimensional accuracy of full arch impressions intraorally. CI is still significantly more accurate than full arch scans with intraoral scanners in clinical use. CLINICAL SIGNIFICANCE: Conventional full arch impressions with polyether impression materials are still more accurate than full arch digital impressions. Digital impression systems using powder application and active wavefront sampling technology achieve the most accurate results in comparison to other intraoral scanning systems (DRKS-ID: DRKS00009360, German Clinical Trials Register).

Alveolar echinococcosis in the zoological garden Basle.

Alveolar echinococcosis (AE) is a rare, but potentially severe zoonotic disease caused by Echinococcus (E.) multilocularis. Recent findings indicated an increasing importance of AE for non-human primates living in regions endemic for E. multilocularis. The death of five cynomolgus monkeys (Macaca fascicularis) and a lowland gorilla (Gorilla g. gorilla) due to AE raised concern about the incidence of this parasite in the Basle Zoo. Consequently, a project was initiated to investigate the prevalence amongst an affected group of cynomolgus monkeys, as well as in foxes and mice. Three out of 46 monkeys were seropositive for E. multilocularis antigen. In two of these monkeys and in another three animals, which were seronegative, structures compatible with metacestodal cysts were observed using ultrasonography. Seven out of 35 free roaming foxes caught at the zoo were positive for an intestinal E. multilocularis copro-antigen ELISA, four of them shed taeniid eggs simultaneously. No lesions compatible with AE were present in 50 necropsied mice from the zoo area. These results indicate that the fox population is a potential source to introduce E. multilocularis and may thus represent a risk for the zoo animals.

Hepatic alveolar echinococcosis in cynomolgus monkeys (Macaca fascicularis).

Alveolar echinococcosis was diagnosed in 12 cynomolgus monkeys (Macaca fascicularis) at postmortem examination within a period of 6 years. Besides consistent involvement of the liver, parasitic lesions were also present in mesenteric lymph nodes, pancreas, lung, and kidney. In the liver, various patterns of host's responses to parasitic tissue could be distinguished. Infiltration of macrophages, often multinucleated, around usually intact metacestodes was the main feature of one pattern. A second pattern was characterized by the presence of abundant, normally degenerate granulocytes in addition to macrophages surrounding collapsed laminated structures. Finally and as a third pattern, some cysts were surrounded by marked collagen deposition, which was usually not a significant feature of the other foci. Parasitic cysts with protoscolices were observed in foci with the first and third pattern but not in the second one. The simultaneous occurrence of all three patterns was observed in most animals. Type AA amyloid was identified either in the space of Dissé, macrophages or blood vessel walls in nine animals using immunohistochemistry. Identity of parasitic structures such as metacestodes of Echinococcus multilocularis was confirmed immunohistochemically. All animals that could be tested serologically (7/12) had detectable antibodies against the E. multilocularis-specific Em2 antigen. Liver lesions of six animals were additionally analyzed by polymerase chain reaction, yielding the amplification of a specific E. multilocularis DNA fragment in each case.

Echinococcus multilocularis in two lowland gorillas (Gorilla g. gorilla).

An unusual presentation of alveolar echinococcosis was observed in two lowland gorillas (Gorilla g. gorilla). Clinical signs included progressive abdominal enlargement, apathy and anorexia. Macroscopical changes consisted of severe peritonitis and foci of hepatic necrosis with large cavities replacing most of the normal tissue. Additionally, a few structures resembling hydatid cysts were present. Histologically, some necrotic areas contained fragments of a laminated wall characteristic of echinococcal metacestodes. Only a few areas showed the multiloculated architecture typical of Echinococcus multilocularis. Serum antibodies against E. multilocularis antigen were detected in both animals, and granulomatous and necrotizing hepatitis with severe peritonitis due to E. multilocularis was diagnosed. The pathological changes in alveolar echinococcosis in gorillas appear to resemble more closely those found in human beings than those in other non-human primates.