Biomedical subjects
A Lussi
Publications and source records attributed to A Lussi.
In vivo performance of the new non-instrumentation technology (NIT) for root canal obturation.
AIM: The aim of this in vivo study was to compare the radiographic quality of root fillings performed by the NIT-obturation method versus conventional mechanical obturation. METHODOLOGY: Sixty-six patients needing root canal treatment participated in this study. The treatments were performed by three private practitioners. The root canals were instrumented with K-Flexofiles to a master apical file between sizes 25 and 60, followed by step-back flaring up to size 70. Copious irrigation was used throughout the instrumentation procedure with NaOCl (3%). The teeth were obturated either by lateral condensation, the McSpadden technique (control) or by the new non-instrumentation technology (NIT) with and without using gutta-percha points. In the NIT method, a low pressure was created within the tooth, and AH 26 sealer was sucked into the root canal system. Radiographs of the root-filled teeth were analysed and the length of the root filling, the presence of voids and the area of any other fillings determined. RESULTS: The root canal fillings of the control group (0.1 +/- 0.1 mm) and those of the NIT/gutta-percha group (0.3 +/- 0.1 mm) were both overextended when taking the apical constriction as a reference point. Root canal fillings of the NIT/gutta-percha group were statistically (P < 0.05) significantly longer than those of the NIT without gutta-percha group. The latter showed slightly underextended root canal fillings (-0.14 +/- 0.1 mm). CONCLUSIONS: The present investigation demonstrated the performance of the NIT-obturation method in vivo. Root canals filled by the reduced-pressure-method using sealer combined with gutta-percha cones exhibited equivalent radiographic quality compared to conventionally filled canals.
Clinical evaluation of the cleansing properties of the noninstrumental technique for cleaning root canals.
AIM: The purpose of the present study was to evaluate noninstrumentation technology (NIT) for root-canal cleansing in vivo. METHODOLOGY: A total of 22 teeth that were to be extracted in 18 patients were treated with NIT for 30 min with 3.0% NaOCl. After extraction, the remaining organic debris in the root canals was evaluated histologically and categorized as the percentage of the corresponding canal length in the apical middle and coronal regions of the roots. Percentage of residual debris was categorized as follows: D1, 0%; D2, 1-50% and D3, 51-100%. RESULTS: In the coronal region, 55% of the roots were totally clean (Dl), whereas 12% and 33% were scored as D2 and D3, respectively. The middle section was evaluated as D1 in 27%, D2 in 18% and D3 in 55%. In the apical region, only 21% of the roots were totally cleaned: the remaining 79% were scored as D3. CONCLUSION: The results indicate that the noninstrumental technique for cleaning root canals needs further modifications for achieving acceptable results under clinical conditions.
Clinical performance of a laser fluorescence device for detection of occlusal caries lesions.
Children and adolescents must be examined often for occlusal caries. Diagnosis of fissure caries is difficult especially when the tooth surface appears seemingly intact. It has been shown that using traditional clinical methods, as little as 20% of teeth with fissure caries under intact surfaces were correctly recognised as such. Therefore, new methods for increasing the accuracy of diagnosis have been sought for years. Recently, a new device, based on fluorescence measurements, was introduced. The purpose of this study was to test the device under in vivo conditions in order to provide recommendations for its use in the dental office. Seven general dental practitioners examined a total of 332 occlusal surfaces in 240 patients. Caries extent was determined for each site after operative intervention (='gold standard'). Clinical inspection and analysis of bitewing radiographs exhibited statistically significant lower sensitivities (31-63%) than did the DIAGNOdent device (sensitivity > or = 92%). It is recommended that the laser device is used in the decision-making process in relation to the diagnosis of occlusal caries as a second opinion in cases of doubt after visual inspection.
Comparison of a new dental trauma splint device (TTS) with three commonly used splinting techniques.
Splinting is the standard of care for stabilization of replanted or repositioned permanent teeth following trauma. The present experimental study compared four dental trauma splints in 10 volunteers. The evaluated splints included a wire-composite splint (WCS), a button-bracket splint (BS), a resin splint (RS), and a new device (TTS=Titanium Trauma Splint) specifically developed for splinting traumatized teeth. All splints were bonded to the labial surfaces of the maxillary lateral and central incisors. Splints were left in place for 1 week. After splint removal, the next splint was placed after a 1-week rest period. The sequence of splint application was randomized for each individual. The following parameters were assessed: tooth mobility with horizontal and vertical Periotest values (PTV) before and after splint application and splint removal, respectively; probing depths, plaque and bleeding on probing indices before splint application and removal, and chair time needed for splint application and removal. After splint application, horizontal PTV were significantly lower in central incisors for BS compared to TTS (P=0.04), and for RS compared to TTS (P=0.005) and to WCS (P=0.006). Reduction of lateral tooth mobility (=splint effect) expressed by the difference between horizontal pre- and postoperative PTV was significantly greater in RS compared to TTS and WCS (P<0.05) for central as well as for lateral incisors. However, changes of vertical tooth mobility were not significant across the splinting techniques. Periodontal parameters remained unchanged, reflecting the excellent oral hygiene by the study subjects. The chair time needed for splint application was significantly shorter for TTS (P<0.01). In conclusion, all tested splints appeared to maintain physiologic vertical and horizontal tooth mobility. However, the latter was critically reduced in RS splints.
Erosive potential of oral care products.
Seven oral care products and orange juice as a positive control were tested for the erosive potential by immersing each enamel specimen (10 per group) into solutions of the various products for 10 and 20 min. Before and after the experiment Knoop surface hardness (SMH) was measured. The enamel microstructure before and after immersion was assessed by scanning electron microscopy and confocal laser scanning microscopy. Orange juice produced the most marked losses of hardness after 10 and 20 min. Among the dental hygiene products only the fluoride-free toothpaste produced a significant reduction of hardness after 10 as well as after 20 min. With the exception of Elmex gel, all tested oral care products led to a significant (p < 0.05) increase of enamel hardness. The results of the hardness measurements corresponded with the microstructure findings. It may, therefore, be concluded that the tested fluoride-containing oral care products do not exhibit any erosive potential, which could be picked up with the methodologies under study.
What is the optimum fluoride concentration needed for the remineralization process?
In vitro experiments could demonstrate that only negligible amounts of fluoride are necessary to promote remineralization of incipient caries lesions. From the clinical point of view, there is evidence that only under certain circumstances is a stabilization of the surface zone of an incipient caries lesion the true mechanism of action of topically applied fluorides. However, an optimum universally valid fluoride concentration needed for this process cannot be defined.
[Amalgam and other restoration materials. Opinion of dentists in 3 different language regions of Switzerland on their side effects. A survey of 1520 men and women dentists in Switzerland].
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[Prevalence and risk factors of root caries. A study of residents over 70 years old in the homes for the aged].
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[The erosive potential of various oral care products compared to foodstuffs and beverages].
The purpose of the present study was to investigate the erosive potential of various oral care products and to compare the results with those of various foodstuffs and beverages. Furthermore, the chosen method of surface hardness measurements was compared with scanning electron microscopy. Seven oral care products (toothpastes and mouth rinses), three foodstuffs and one beverage (as positive control) were tested for their erosive potential. After initial hardness testing 110 enamel specimens were distributed into 11 groups of 10 specimens each in such a way as to have a homogenous hardness distribution per group. The erosive potential of the products was tested by immersing the enamel specimens into solutions of the various products for 10 and 20 minutes. After the experimental period Knoop hardness was measured on the enamel specimens and the differences between before and after were calculated. The micromorphology of native enamel surfaces before and after immersion was determined by SEM on further enamel specimens treated identically for 20 minutes. Apple puree and orange juice produced the most marked losses of hardness after 10 and 20 minutes, respectively. Among the dental hygiene products only the fluoride-free Weleda toothpaste produced a significant reduction of hardness after 10 as well as after 20 minutes. With the exception of Elmex-Gel, all tested dental hygiene products led to a significant (p<0.05) increase of enamel hardness. The results of the hardness measurements corresponded with the micromorphological findings. It may, therefore, be concluded that the tested fluoride-containing oral care products do not exhibit any erosive potential which could be measured with the methodology used in this investigation.
[Dental knowledge and evaluation of school dental care by school graduates in Berne canton].
In 1996, a letter was written to 401 High-School level graduates of 20 randomly selected schools in the canton of Berne, Switzerland. Out of these 401, 343 individuals could be interviewed and subsequently be given a clinical examination comprising a plaque revealing test. The average plaque index was 70%. The assessment of the questionnaires showed a comprehensive basic dental knowledge of the students so that reasonable care of their teeth could be expected. Whereas almost everyone used a toothbrush regularly, flossing fell short in the majority of the cases. Outside the class-rooms, concentrated F-preparations were hardly used systematically. Besides parents and the family, dentists and specifically trained auxiliaries (school dental health assistants, SDHA) were found to play a central role in the mediation of theoretical knowledge and in the practical instruction of oral hygiene procedures. They received mostly good grades by the students for their work. The regular teaching staff, however, fell clearly behind the SDHAs. In spite of the obviously big influence on the youth, the dentists play only an insignificant role in some places. Overall, the students consider dental health education as relatively important placing it on the same level as sex education. Since SDHAs do not visit the classes during the last five years any longer, teaching of dental prophylaxis has been reduced in many communities to fluoridation with concentrated F-preparations. Negative consequences such as uncertainty regarding tooth brushing techniques, handling dental floss and questions as to oral hygiene behavior after leaving school have already been registered. With the academic year 2000/01 one visit by an SDHA to the upper level classes (last five years) was reintroduced. This tepid reaction by the Bernese education authority to a massive weakening of public dental health promotion will hardly suffice to keep up the remarkable level of dental prevention reached over the past decades, let alone to warrant substantial progress. The study has also demonstrated that the acquisition of knowledge is based on repetitive efforts. This is the fundamental reason for systematic monitoring and re-instruction of dental hygiene procedures also during the last five classes of mandatory scholarity.
A comparison of the erosive potential of different beverages in primary and permanent teeth using an in vitro model.
The aim of this study was to compare the erosive potential of different beverages and foodstuffs in primary and permanent teeth. Sixty primary and 60 permanent human teeth were immersed for 3 min in the solution under study (5 teeth per treatment group). Surface microhardness was measured before and after exposure. Initial (baseline) surface microhardness was lower for primary teeth than for permanent teeth. In both primary and permanent teeth, Sprite showed the highest decrease in surface microhardness, whereas yogurt showed an increase in surface microhardness in the primary teeth. Overall decrease was 27.2 +/- 17.5 KHN (mean +/- SD) for primary and 25.9 +/- 15.6 KHN for permanent teeth. The comparison of the erosive susceptibility in this in vitro model showed that primary teeth were not more susceptible to erosion compared to permanent teeth.
Long-term obturation quality using noninstrumentation technology.
The aim of the study was to evaluate and compare the sealing quality of hand- or vacuum-obturated root canals after hand instrumentation or noninstrumentation cleansing. A total of 60 single-rooted teeth were divided into six comparable groups. The root canals of three groups were instrumented with the balanced-force technique and obturated with gutta-percha condensation. The remaining teeth were cleansed and filled using noninstrumentation technology and the same sealers as with hand instrumentation (AH Plus, Apexit, Pulp canal sealer EWT). After aging the quality of coronal seal was assessed with a dye penetration method after perfusion with the dye under vacuum. The results of this study indicated superior sealing of the machine-filled roots (noninstrumentation technology), compared with laterally condensed conventionally filled root canals.
[The cleaning and obturation of the root canal system without conventional instruments. A position definition].
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[Amalgam and other restoration materials. The opinion of dentists in the 3 linguistic regions of Switzerland (2)].
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Comparison of two devices for root canal cleansing by the noninstrumentation technology.
Optimal cleansing of the root canal system is a prime prerequisite for long-term success in endodontics. Recently, a new method and device were presented providing "automatic" root canal cleansing without the need of endodontic instrumentation. Cleanliness results equivalent to or better than those with conventional methods were achieved in considerably less time. The purpose of the present study was 2-fold: (a) optimization of the device to make it applicable to patients and (b) to measure its effectiveness against the predecessor model. A total of 156 root canals of 66 freshly extracted vital human molars were cleansed with the new device and their cleanliness compared with that of 149 canals of 52 molars cleansed previously with the first apparatus. Data indicated that the smaller new machine produced equivalent or better cleanliness results in the root canal system using significantly less irrigant (NaOCl).
A computerized analysis of the relation between the occlusal enamel caries lesion and the demineralized dentin.
It has previously been shown that the demineralized dentin does not spread laterally along the enamel-dentin junction in non-cavitated approximal lesions. This study examined the spread of the dentinal part of occlusal lesions along the enamel-dentin junction. The material consisted of 48 well-defined occlusal lesions with histological evidence of dentin demineralization. The teeth were embedded in methylmethacrylate, serially-sectioned, ground, and contrast-stained. The sections with the deepest lesion penetration from each lesion were photographed and scanned by a high-quality scanner in order to produce images for computerized histomorphometric analysis. Two variables were measured on the images: i) the length of the contact area of the enamel lesion along the enamel-dentin junction; and ii) the length of the contact area of the demineralized part of the dentin lesion along the enamel-dentin junction. The results showed a gradual increase in the lengths of the enamel and dentin contact areas between the sections, each representing well-defined progressive stages of lesion formation. In two-thirds of the non-cavitated lesions, the enamel lesion was larger than the demineralized part of the dentin lesion, and in 50% of the cavitated cases the extension of the demineralized dentin was less than the affected enamel. Our conclusion is that the dentin demineralization did not spread significantly in a lateral direction in non-cavitated occlusal lesions.
Obturation of root canals with different sealers using non-instrumentation technology.
AIM: To evaluate and compare the sealing quality of hand- or vacuum-obturated root canals after hand preparation or hydrodynamic cleansing of root canals, respectively. METHODOLOGY: After assessing root curvature, 96 single-rooted deep-frozen teeth were divided into eight comparable groups. The root canals of four groups were instrumented with the balanced force technique. The remaining uninstrumented teeth were connected to a reduced-pressure device (NIT) and the root-canal system perfused with 2.5% NaOCl under alternating pressure fields. This dissolved the pulpal tissues and removed debris from the root-canal system. The canals of the hand-instrumented groups were obturated using the cold lateral condensation method with guttapercha and one of four different sealers (AH26, AH Plus, Apexit and Pulp Canal Sealer EWT). The teeth treated with the alternating pressure device (NIT) were obturated by a vacuum obturation method (NIT) with the same four sealers. The quality of the coronal seal was assessed using a dye penetration method. In order to minimize errors the roots were perfused with water before exposure to the dye, under vacuum. The teeth were then rendered transparent and the depth of penetration of the dye between the wall of the canal and the obturating material was measured with a stereomicroscope. RESULTS: The canals cleaned and filled by NIT showed statistically significantly less dye penetration than those obturated by lateral condensation (P < 0.05). Within the NIT group, Pulp Canal Sealer EWT exhibited significantly more dye penetration than Apexit. Amongst the control lateral condensation groups no significant differences were found between the various sealers. CONCLUSIONS: The present investigation demonstrated the validity of the NIT obturation method in combination with commonly used root-canal sealers.