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Biomedical subjects

A Lussi

Publications and source records attributed to A Lussi.

At least 55 records · Page 3Linked to original sources
PubMed1999

Caries-risk assessment.

Dental caries has a multifactorial aetiology in which there is an interplay of three principal factors: the host (saliva and teeth), the microflora (plaque), and the substrate (diet), and a fourth factor: time. There is no single test that takes into consideration all these factors and can accurately predict an individual's susceptibility to caries. The risk of dental caries can be evaluated by analysing and integrating several causative factors. These include caries experience (initial caries lesions and established caries defects, secondary caries and present caries activity), fluoride use, extent of plaque present, diet, bacterial and salivary activity and social and behavioural factors.

Adolescent↗
PubMed1999

A retrospective study of dental conditions of captive brown bears (Ursus arctos spp.) compared with free-ranging Alaskan grizzlies (Ursus arctos horribilis).

The teeth of 63 skulls of brown bears (Ursus arctos spp.) that had lived in the Bernese bear pit between 1850 and 1995 were examined and radiographed for occlusion, loss of teeth, calcified dental plaque and calculus, attrition, and caries. Dental pathology and periodontal status were evaluated with respect to age and location in the dentition. Further techniques such as computed tomography, microhardness testing, histologic sectioning, and scanning electron microscopy were used in selected cases to verify the macroscopic and radiographic diagnoses. Fourteen skulls originating from free-ranging wild Alaskan brown bears (Ursus arctos horribilis) were examined as a control group. For zoo bears over 10 yr old, severe enamel and dentinal attrition has been observed in canine teeth, with exposed pulp and proximal lesions in molar teeth. Deposits of calcified dental calculus were found in various locations and increased with age. A much lower degree of calculus deposition was found in the Alaskan grizzlies, whose average caries frequency was higher but with large individual variation and different locations in canine teeth and occlusal lesions in molar and premolar teeth. Radiographic evaluation of perialveolar osteolytic processes revealed a greater frequency of apical and combined apical-marginal lesions of the alveoli in zoo bears over 10 yr old. Stereotypical behavior like cage chewing is a suspected cause of canine tooth and secondary alveolar lesions, whereas a nutritionally inappropriate diet and inadequate opportunities for tooth-cleaning activities are responsible for the lack of natural cleaning and the extensive calculus formation that results. The methods used in this study are useful in assessing and comparing the dental health status of free-ranging bears, and those living in zoological gardens, by evaluating anesthetized bears or bear skull collections representing both groups.

Age Factors↗
PubMed1998

Bone response to unloaded and loaded titanium implants with a sandblasted and acid-etched surface: a histometric study in the canine mandible.

Many dental clinical implant studies have focused on the success of endosseous implants with a variety of surface characteristics. Most of the surface alterations have been aimed at achieving greater bone-to-implant contact as determined histometrically at the light microscopic level. A previous investigation in non-oral bone under short-term healing periods (3 and 6 weeks) indicated that a sandblasted and acid-etched titanium (SLA) implant had a greater bone-to-implant contact than did a comparably-shaped implant with a titanium plasma-sprayed (TPS) surface. In this canine mandible study, nonsubmerged implants with a SLA surface were compared to TPS-coated implants under loaded and nonloaded conditions for up to 15 months. Six foxhound dogs had 69 implants placed in an alternating pattern with six implants placed bilaterally in each dog. Gold crowns that mimicked the natural occlusion were fabricated for four dogs. Histometric analysis of bone contact with the implants was made for two dogs after 3 months of healing (unloaded group), 6 months of healing (3 months loaded), and after 15 months of healing (12 months loaded). The SLA implants had a significantly higher (p < 0.001) percentage of bone-to-implant contact than did the TPS implants after 3 months of healing (72.33 +/- 7.16 versus 52.15 +/- 9.19; mean +/- SD). After 3 months of loading (6 months of healing) no significant difference was found between the SLA and TPS surfaced implants (68.21 +/- 10.44 and 78.18 +/- 6.81, respectively). After 12 months of loading (15 months of healing) the SLA implants had a significantly greater percentage (p < 0.001) of bone-to-implant contact than did the TPS implants (71.68 +/- 6.64 and 58.88 +/- 4.62, respectively). No qualitative differences in bone tissue were observed between the two groups of implants nor was there any difference between the implants at the clinical level. These results are consistent with earlier studies on SLA implants and suggest that this surface promotes greater osseous contact at earlier time points compared to TPS-coated implants.

Acid Etching, Dental↗
PubMed1998

Evaluation of filling materials in membrane--protected bone defects. A comparative histomorphometric study in the mandible of miniature pigs.

In recent years, bone grafts and bone substitutes have been increasingly utilized underneath barrier membranes to optimize the treatment outcome of bone reconstructive therapy for defects in the alveolar process. In the present study, 4 different filling materials were evaluated in bone defects of similar dimensions in the mandible of miniature pigs. Blood clots and autografts were used as controls. The defects were covered with barrier membranes and allowed to heal for 4, 12 or 24 weeks. Histologic examination demonstrated that bone repair progressed through a programmed sequence of maturation steps closely resembling the pattern of bone development and growth regardless of whether bone grafts or substitutes were present or not. Histomorphometric analysis showed that autologous bone grafts (autografts) had the best osteoconductive properties during the initial healing period, with 39% of newly formed bone inside the membrane-covered defects at 4 weeks of healing. In addition, 87% of the graft surfaces were already covered by bone at this time. Both values were significantly higher for autografts than for the 4 alternative bone fillers (P < or = 0.05). At 12 weeks, these differences were no longer apparent, with all 5 filling materials showing similar values. Among the tested bone substitutes, tricalcium phosphate (TCP) showed a significantly higher percentage of bone fill at 24 weeks of healing. It can be concluded that sites filled with autografts clearly demonstrated the best results underneath barrier membranes in the early phase of healing. As far as degradation and substitution are concerned, TCP showed the most promising results. This filler, however, needs to be tested further in a more demanding animal model. Less favorable results were obtained for coral-derived hydroxyapatite granules and for demineralized freeze-dried bone allografts.

Alveolar Bone Loss↗
PubMed1998

Dental health status and endodontic treatment of captive brown bears (Ursus arctos ssp.) living in the Bernese bear pit.

The teeth of five adult captive brown bears (Ursus arctos ssp.) were examined and radiographed for occlusion, loss of teeth, dental plaque and calculus, and attrition under general anesthesia. Deposits of dental calculus were found in various locations with an overall prevalence of 8% to 15% of all tooth surfaces. In all five animals, severe enamel and dentinal attrition defects were observed in canine teeth with exposed pulp. Cage-chewing behavior is probably the main cause for the dental attrition. The composition of the food and feeding management are most likely responsible for the lack of natural cleaning and the resulting plaque and calculus formation. All affected canine teeth were treated with endodontic procedures using several materials and techniques, and evaluated one- to two-and-a-half years later by clinical examination, radiography, and scanning electron microscopy of silicone casts of the treated teeth. All coronal fillings were tight. The apices were not completely sealed in two teeth. We conclude that the use of adequate and specialized instrumentation and techniques for the treatment of these long, curved, large diameter root canals is more important than the particular endodontic and restorative materials used. The dental health status of zoo animals is an indicator of their general well-being. Preventive measures should be taken in their environment and management to minimize the risk of dental conditions.

Animals↗
PubMed1997

[Amalgam problems: recommendations on patient assessment and counseling].

Assessment of patients with alleged or supposed amalgam-associated problems is difficult. Various methods, classified as medical, dental and "traditional" are discussed. Medical methods comprise epicutaneous sensitivity testing and determination of the mercury concentration of various body fluids such as saliva, urine and blood. Patients with amalgam restorations regularly exhibit increased readings. However, such measurements are not very appropriate since there are no generally applicable threshold values. Dental examination focuses primarily on oral lichenoid lesions of the mucosa in the vicinity of alloy restorations. Aggravation of a patient's general health status and/or exacerbation of pre-existing symptoms following the insertion or removal of an alloy filling may be indicative for amalgam incompatibility. Recommendations for everyday practice are given.

Body Fluids↗
PubMed1997

Erosion on abraded dental hard tissues by acid lozenges: an in situ study.

The aim of this study was to analyse the erosive effect of acidic lozenges and to compare it with that of orange juice, known to have the capacity to cause erosion. Two acidic, sugar-free lozenges and orange juice were tested in situ in nine patients. Changes in surface Knoop microhardness and change in the surface texture were assessed. The results revealed that orange juice and one acidic lozenge were--under the conditions of this experiment--capable of significantly softening abraded enamel (P < or = 0.017). It was concluded that excessive consumption of acidic lozenges could have the potential to enhance existing dental erosion.

Adult↗
PubMed1997

Obturation of root canals in vivo with a new vacuum technique.

It was demonstrated in vitro that it is possible to achieve obturation of the root canal system with a system utilizing a reduced pressure of 15 hPa (15 mbar). The purpose of this study was to develop a procedure to reach a vacuum of at least 15 hPa within root canals in vivo. It was also determined if root canals could be obturated in daily practice with this vacuum technique. After hand instrumentation of the root canals a tooth was prepared for obturation of the canals with the new technique by obtaining a tightly fitting attachment to a vacuum pump. The result showed that it was possible in vivo to reach reduced absolute pressures of 10 hPa in roots and to fill the root canal system with the new system.

Dental Pulp Cavity↗
PubMed1996

Dental erosion clinical diagnosis and case history taking.

Dental erosion is not a very rare condition. Early correct diagnosis of this damage of dental hard tissue consequently is of clinical importance. The aim of this paper is to present an easy-to-learn rating scheme for the assessment of the severity of dental erosive lesions with high inter- and intra-examiner agreement. It differentiates between facial, occlusal and oral surfaces of a tooth and has already been used successfully in epidemiological studies. Further, anamnestic risk factors are discussed with respect to their relevance for the development of dental erosion. Guidelines are given for the clinician on how to elicit information from the patient about relevant risk factors.

Acids↗
PubMed1996

Impact of including or excluding cavitated lesions when evaluating methods for the diagnosis of occlusal caries.

The aim of this study was to assess different methods for the diagnosis of fissure caries when employed on 37 extracted teeth with cavitated occlusal surfaces. A further aim was to compare these results with a previous assessment of the same diagnostic methods on 63 non-cavitated teeth [Lussi, 1993]. The examinations were performed under standard conditions in a professional dental unit. The methods employed were: visual inspection (VI, 26 dentists), VI with magnification (VIM, x2, 26 dentists), bite-wing radiography (BW, 24 dentists), VI combined with BW (VI + BW, 10 dentists) and VI combined with light-pressure probing (VI + P, 23 dentists). For information about the reproducibility, the VI and the VI + BW were repeated. After the last inspection, the teeth were histologically prepared, serially sectioned perpendicular to the occlusal surface and diagnosed for the presence of caries. The agreement between histological and clinical diagnosis was assessed. Sensitivities were VI = 62%, VIM = 75%, BW = 79%, VI + BW = 90%, and VI + P = 82%. The sensitivities found by the same dentists diagnosing non-cavitated teeth were VI = 12%, VIM = 20%, BW = 45%, VI + BW = 49%, VI + P = 14%. The differences between these sensitivities have a direct impact on the DMFS reported for fissure caries. It was concluded that the significant influence of the surface status (cavitated/non-cavitated) should be taken into account when comparing different methods for the diagnosis of occlusal caries.

Analysis of Variance↗
PubMed1996

[Differential diagnosis of resorptive tooth diseases and caries].

Feline Odontoclastic Resorptive Lesions (FORL, previously known as "neck lesions") on cat teeth are compared to caries and differentiated with the use of new methods. Radiological examination reveals typical odontoclastic resorptive processes, which take place at the dental root and at the periodontium. These lesions demonstrate the destruction on the desmodontium and the following ankylosing reaction. The rhodamine B stain which is selective for caries, stains regions which are softened by caries in a dark red way. Fuchsin/Acetic-Light Green stained histological preparations demonstrate the resorptive lacunae, resorptive lagoons and resorptive canals. Giant cells with multiple nuclei and reparative cementum can also be shown with the same stain. Hardness measurements using a Knoop diamond (KHN Knoop hardness number) give information about the degree of hardness of the different tissues. Electron microscopic investigations are performed to show the dentinal tubules and allowing the differentiation between FORL and caries. Since FORL also has been found in wild cats we deduced that alimentation has no effect on the pathogenesis of the disease.

Animals↗
PubMed1995

Threshold of tactile sensitivity perceived with dental endosseous implants and natural teeth.

The aim of this study was to determine the threshold of tactile perception of endosseous dental implants and to assess the relative difference of that threshold between implants and teeth. Twenty-two subjects with implants of the ITI Dental Implant System were included in the study. All implants served as abutments for single tooth crowns and had been in function for a minimum of 1 year. A strain gauge glued to the shaft of an amalgam plugger served as a force sensor. It transformed the elastic deformation exerted onto the shaft into an electronic signal for recording. By use of the amalgam plugger, a continuously increasing force was exercised on the implants or teeth until the first sensation of touch was indicated by the patient. Statistical analysis revealed threshold values for the implants ranging from 13.2 to 189.4 g (1 g = 0.01 N) (mean 100.6; SD 47.7), while a range of 1.2 to 26.2 g (mean 11.5; SD 11.5) was found for control teeth. Thus, the mean threshold values for implants were 8.75 times higher than for teeth. This difference was highly statistically significant. A general linear models procedure was applied to determine the influence of patient age, jaw, implant position and the threshold values of teeth on the measurements obtained for implants. Only gender and the threshold values for contralateral teeth had a significant influence. These 2 parameters together explained 27% of the variability in threshold measurements. It is concluded that a more than 8-fold higher threshold value for tactile perception exists for implants compared with teeth.

Adolescent↗
PubMed1995

A new non-instrumental technique for cleaning and filling root canals.

The aim of this in vitro study was to test the ability of a novel non-instrumental technique to prepare and obturate root canals. Cleaning of the root canal system was achieved with a device which was able to develop, under reduced pressure, controlled cavitation. The same device was used for proper drying and subsequent obturation of the root canal system. A total of 55 freshly extracted molars with 120 canals were treated either by the step-back technique and lateral condensation of gutta-percha and AH26 as a sealer or by the new device. The teeth were then sectioned horizontal to the long axis of the root canal and examined by light microscopy. The cross-sectional area, area with residual pulpal tissue and voids were assessed morphometrically. Overall, the treatment with the new device resulted in similar cleanliness and obturation quality when compared with the control group. Total treatment time using the new non-instrumental technique, however, was less than half of that using hand instrumentation.

Analysis of Variance↗
PubMed1995

Condensation pressure during amalgam placement in patients.

The purpose of this study was to investigate the condensation pressure during amalgam placement in patients. Forty-four practitioners were asked to fill two class 2 cavities in the lower jaw on their patients in their own practice with the aid of a force-measuring plugger. This device, with semiconductor strain gauges, allowed the dentist to have an identical tactile feedback as with any other plugger. Three different amalgams, with different shapes of alloy particles, were tested. The results showed a maximum condensation pressure of 8.9+/-2.4 MPa and 5.5+/-1.8 MPa with a small and a large amalgam plugger, respectively. Average condensation pressures were 3.7+/-1.3 MPa for the small and 2.2+/-0.9 MPa for the large instrument. The total working time required to fill a cavity was on average 131 s; the amalgam was effectively condensed for 44 s. No significant differences between amalgams with different shapes of alloy particles, no influence of time of day, and no difference between female and male dentists were found. This study showed that the condensation pressure is lower than often recommended, and that it is not statistically different from the values obtained in a previous laboratory study.

Chemical Phenomena↗
PubMed1995

In vivo diagnosis of fissure caries using a new electrical resistance monitor.

The aim of this investigation was to study the accuracy of a newly developed electrical resistance monitor in diagnosing occlusal fissure caries in vivo in teeth without cavitation. The electrical resistance was measured in vivo on human third molars without existing restorations and without any macroscopic carious cavitation. Data from 41 sites on 26 occlusal surfaces were obtained. After measurement, the teeth were extracted, histologically prepared, and serially sectioned perpendicular to the occlusal surface and examined for the presence of caries. Nineteen sites had no caries, 7 had enamel caries, and 15 sites showed dentinal caries, 4 of which deep dentinal caries. For the diagnosis of occlusal caries with the electrical resistance monitor, the specificity was 0.77, the sensitivity 0.93, and the accuracy 0.83. Likelihood ratios for four diagnostic levels (no caries, enamel caries, dentinal caries, and deep dentinal caries) were 0.09, 0, 3.47, and 4.16, respectively. Diagnosis of occlusal caries using conventional bite-wing radiographs showed a specificity of 0.77, a sensitivity of 0.62, and an accuracy of 0.71. The electrical resistance monitor was well suited to detect in vivo occlusal caries under clinically intact fissures. The rather high value (0.23) of false-positive ratings, however, might lead to a substantial number of sound teeth being restored unnecessarily. Substantial improvement of occlusal, caries diagnosis may be achieved by combining this method with others.

Adult↗