Biomedical subjects

Adrian Lussi

Publications and source records attributed to Adrian Lussi.

At least 19 recordsLinked to original sources

PubMed2006

Penetration ability and microleakage of a fissure sealant applied on artificial and natural enamel fissure caries.

OBJECTIVES AND METHODS: This study investigated the sealing ability of a current available unfilled fissure sealant applied over sound (n=80), artificially created (n=80) and naturally carious fissures (n=80) under different humidity conditions (90+/-2 and 45+/-2% relative humidity) and etching times (40 and 60s). All samples were submitted to 5000 thermal cycles and examined by light microscopy after sectioning. Microleakage, penetration ability, fissure type, fissure entrance angle, sealant occlusal length, caries location and caries depth were assessed. RESULTS: The significantly longer sealant occlusal length and larger entrance angle exhibited by shallow fissures, contributed to their higher microleakage and smaller amounts of unfilled areas compared to deep fissures. Sealant microleakage was significantly influenced by the condition of the enamel (sound, artificial and natural caries) and the caries location in the fissures, but not by enamel caries depth (D1 and D2), etching time, or humidity condition. Natural caries exhibited significantly higher microleakage than sound or artificially created carious fissures. CONCLUSIONS: Based on the results of this study, it can be concluded that location of caries in the fissure rather than its depth should be taken into account when applying a fissure sealant. When the borders of the fissure sealant are on carious enamel, a significantly higher microleakage must be expected. The artificial caries model was not a suitable method to assess the behavior of natural fissure caries.

Dental Caries↗

PubMed2006

Evaluation of cavitations in proximal caries lesions at various magnification levels in vitro.

OBJECTIVES: The aim of this study was to evaluate the cavitation rate of proximal caries using different magnification aids in vitro. METHODS: Radiographs of 285 extracted teeth were taken and the proximal surfaces were graded to the criteria R0 (no radiolucency), R1 (radiolucency confined to the outer half of enamel), R2 (inner half of enamel) and R3 (outer half of dentin). Subsequently, the proximal surfaces were checked for the presence of cavitations with the naked eye (NE), and by using 4.3 x magnification eyeglasses (ME), a stereo microscope (SM, 10x), or a scanning electron microscope (SEM, up to 2000 x magnification). RESULTS: In surfaces with R3 caries, cavitations were visible in 56 of 59 cases with the naked eye. When using SEM, all surfaces revealed cavitations (100%). Regarding the surfaces with R2 lesion, 36 of 46 cases showed cavitations (NE); the corresponding values were 39/46 (ME), 41/46 (SM), and 46/46 (SEM); in the latter, in most cases deep defects could be observed. With regard to R1 lesions, 36/60 (NE), 43/60 (ME), 45/60 (SM), and 58/60 (SEM) cases revealed cavitations. A breakdown of radiographically sound surfaces (R0) was present in some 10% of the examined surfaces (24/261, NE; 33/261, SEM). CONCLUSIONS: Cavitations (defined as breakdown of the surface) are present in significantly more cases than previously reported. This might be an explanation why even small radiolucencies tend to progress, albeit slowly. Thus, close follow-ups should strongly be recommended when considering a preventive treatment regimen with small radiolucencies.

Dental Caries↗

PubMed2006

Prevalence, incidence and distribution of erosion.

There is some evidence that the presence of erosion is growing steadily. Because of different scoring systems, samples and examiners, it is difficult to compare and judge the outcome of the studies. Preschool children aged between 2 and 5 years showed erosion on deciduous teeth in 6-50% of the subjects. Young schoolchildren (aged 5-9) already had erosive lesions on permanent teeth in 14% of the cases. In the adolescent group (aged between 9 and 17) 11-100% of the young people examined showed signs of erosion. Incidence data (= increase of subjects with erosion) evaluated in three of these studies were 12% over 2 years, 18% over 5 years and 27% over 1.5 years. In adults (aged between 18 and 88), prevalence data ranged between 4 and 82%. Incidence data are scarce; only one study was found and this showed an incidence of 5% for the younger and 18% for the older examined group (= increase of tooth surfaces with erosion). Prevalence data indicated that males had somewhat more erosive tooth wear than females. The distribution of erosion showed a predominance of occlusal surfaces (especially mandibular first molars), followed by facial surfaces (anterior maxillary teeth). Oral erosion was frequently found on maxillary incisors and canines. Overall, prevalence data are not homogeneous. Nevertheless, there is already a trend for more pronounced rate of erosion in younger age groups. Therefore, it is important to detect at-risk patients early to initiate adequate preventive measures.

Adolescent↗

PubMed2006

Understanding the chemistry of dental erosion.

The mineral in our teeth is composed of a calcium-deficient carbonated hydroxyapatite (Ca10-xNax(PO4)6-y(CO3)z(OH)2-uFu). These substitutions in the mineral crystal lattice, especially carbonate, renders tooth mineral more acid soluble than hydroxyapatite. During erosion by acid and/or chelators, these agents interact with the surface of the mineral crystals, but only after they diffuse through the plaque, the pellicle, and the protein/lipid coating of the individual crystals themselves. The effect of direct attack by the hydrogen ion is to combine with the carbonate and/or phosphate releasing all of the ions from that region of the crystal surface leading to direct surface etching. Acids such as citric acid have a more complex interaction. In water they exist as a mixture of hydrogen ions, acid anions (e.g. citrate) and undissociated acid molecules, with the amounts of each determined by the acid dissociation constant (pKa) and the pH of the solution. Above the effect of the hydrogen ion, the citrate ion can complex with calcium also removing it from the crystal surface and/or from saliva. Values of the strength of acid (pKa) and for the anion-calcium interaction and the mechanisms of interaction with the tooth mineral on the surface and underneath are described in detail.

Calcium↗

PubMed2006

Chemical factors.

pH value, calcium, and phosphate and to a lesser extent fluoride content of a drink or foodstuff are important factors explaining erosive attack. They determine the degree of saturation with respect to tooth minerals, which is the driving force for dissolution. Solutions oversaturated with respect to dental hard tissue will not dissolve it. Addition of calcium (and phosphate) salts to erosive drinks showed protection of surface softening. Today, several Ca-enriched soft drinks are on the market or products with naturally high content in Ca and P are available (such as yoghurt), which do not soften the dental hard tissue. The greater the buffering capacity of the drink or food, the longer it will take for the saliva to neutralize the acid. The buffer capacity of a solution has a distinct effect on the erosive attack when the solution remains adjacent to the tooth surface and is not replaced by saliva. A higher buffer capacity of a drink or foodstuff will enhance the processes of dissolution because more ions from the tooth mineral are needed to render the acid inactive for further demineralization. Further, the amount of drink in the mouth in relation to the amount of saliva present will modify the process of dissolution. There is no clear-cut critical pH for erosion as there is for caries. Even at a low pH, it is possible that other factors are strong enough to prevent erosion.

Beverages↗

PubMed2006

Biological factors.

Biological factors such as saliva, acquired dental pellicle, tooth structure and positioning in relation to soft tissues and tongue are related to dental erosion development. Saliva has been shown to be the most important biological factor in the prevention of dental erosion. It starts acting even before the acid attack, with the increase of the salivary flow rate as a response to the acidic stimuli. This creates a favorable scenario, increasing the buffering system of saliva and effectively diluting and clearing acids on dental surfaces during the erosive challenge. Saliva plays a role in the formation of the acquired dental pellicle, which acts as a perm-selective membrane preventing contact of the acid with the tooth surfaces. The protective level of the pellicle seems to be regulated by its composition, thickness and maturation time. Due to its mineral content, saliva can also prevent demineralization as well as enhance remineralization. However, these preventive and reparative factors of saliva may not be enough against highly erosive challenges, leading to erosion development. The progress rate of erosion can be significantly influenced by the type of dental substrate, occurrence of mechanical and chemical attacks, fluoride exposure, and also by contact with the oral soft tissues and tongue.

Biology↗

PubMed2006

Occupation and sports.

In rare cases the occupation - be it at work or during professional and strenuous sports activities - may give a clue to a patient's risk factors for dental erosion. However, no detrimental effects were described on a population level. Frequent contact to inorganic or organic acids at work could increase the occurrence and progression of erosion. In some studies, acid workers had significantly more teeth with erosive tooth wear than the controls. Clinical findings showed erosion mainly on upper anterior teeth and dentine hypersensitivity. Occupation groups at risk would mostly be found in the chemical industry, but also others like wine tasters may have dental erosion. A few case reports and studies have reported an association between sports activities and erosive tooth wear. The cause could be direct acid exposure or strenuous exercise, which may increase gastroesophageal reflux. Risk groups are swimmers exercising in water with low pH and athletes consuming frequently erosive sport drinks. It has to be kept in mind that sports drinks and occupation can be for some patients a cofactor in the development or in the increase of dental erosion. However, it is unlikely that one or two isolated factors will be responsible for this multifactorial condition.

Acids↗

PubMed2006

Restorative therapy of erosion.

When substance loss caused by erosive tooth wear reaches a certain degree, oral rehabilitation becomes necessary. Prior to the most recent decade, the severely eroded dentition could only be rehabilitated by the provision of extensive crown and bridge work or removable overdentures. As a result of the improvements in composite restorative materials, and in adhesive techniques, it has become possible to rehabilitate eroded dentitions in a less invasive manner. However, even today advanced erosive destruction requires the placement of more extensive restorations such as ceramic veneers or overlays and crowns. It has to be kept in mind that the etiology of the erosive lesions needs to be determined in order to halt the disease, otherwise the erosive process will continue to destroy tooth substance. This overview presents aspects concerning the restorative materials as well as the treatment options available to rehabilitate patients with erosion, from minimally invasive direct composite reconstructions to adhesively retained all-ceramic restorations. Restorative treatment is dependent on individual circumstances and the perceived needs and concerns of the patient. Long-term success is only possible when the cause is eliminated. In all situations, the restorative preparations have to follow the principles of minimally invasive treatment.

Ceramics↗

PubMed2006

The impact of ozone treatment on enamel physical properties.

PURPOSE: To assess the effects of the highly reactive molecule of ozone on sound enamel physical properties and its effects on sealing ability. METHODS: The effect of ozone on sealant tag length, microleakage and unfilled area proportion were evaluated on intact and prepared sound molar fissures. Microhardness, contact angle and acid resistance tests were performed on ground sound smooth surfaces. The samples were treated with ozone for 40 seconds (HealOzone). Control samples were treated with air (modified HealOzone) or left untreated. RESULTS: No statistically significant difference was observed between the control and ozone treated samples in all tests. Prepared fissures exhibited no unfilled areas and a statistically significantly lower microleakage compared to intact fissures. Ozone was shown to dehydrate enamel and consequently enhance its microhardness, which was reversible.

Acid Etching, Dental↗

PubMed2006

Fruit yogurt: any erosive potential regarding teeth?

OBJECTIVE: The capability of drinks and foods to resist pH changes brought about by salivary buffering may play an important role in the dental erosion process in children. The aim of the present study was to test fruit yogurt, a popular snack for children, and the degrees of saturation (pK-pl) with respect to hydroxyapatite and fluorapatite to determine their erosive potential. METHOD AND MATERIALS: A variety of fruit yogurt was tested. To test the pH, 8 readings were taken with a pH electrode for each yogurt. Calcium content was detected by atomic absorption spectrophotometer, phosphorus by the inductively coupled plasma method, and fluoride content by ion chromatography. The degrees of saturation of hydroxyapatite and fluorapatite were calculated by use of a computer program. Statistical analysis was performed using 2-tailed analysis of variance (P < .05) and a post hoc test (Tukey) to determine differences between groups. RESULTS: The pH of each fruit concentrate was significantly different, except for banana yogurt. Except for the phosphorus content of raspberry yogurt, the calcium and phosphorus content for each fruit concentrate were significantly different. Fluoride levels were the same for all yogurts tested, and the degrees of saturation of hydroxyapatite and fluorapatite was positive, indicating supersaturation. CONCLUSION: It could be stated that fruit yogurt has no erosive potential.

Analysis of Variance↗

PubMed2006

[Natal and neonatal teeth].

Natal teeth have been defined as teeth which are present at birth, while neonatal teeth erupt during the first 30 days. Their occurrence is rare, the prevalence ranges from 1:2000 to 1:3000 with a higher frequency in the lip and palate clefts and syndroms. In about 85% natal or neonatal teeth are lower central incisors (60% in pairs), rare are upper teeth, molars and multiple teeth. In almost 90% they are part of the deciduous dentition. A lot of possible causes of early eruption are discussed, but only the relation to hereditary factors seems to be evident. An autosomal dominant trait is often described. The appearance of these teeth is dependent on the degree of maturity, but most of the time it is loose, small, discoloured and hypoplastic. Histologically, enamel hypoplasia with normal prism structure is apparent. No significant disturbances of the dentin structures are observed, only cervically dentin becomes atubular with spaces and enclosed cells. A large vascular pulp and failure of root formation are further investigations. Our microhardness measurements showed values from 24.3-32.4 KHN for enamel and 48.3-62.2 KHN for dentin, while normal deciduous teeth have an enamel hardness of 322.0 +/- 17.5 KHN. The thickness of enamel was never more than 280 microm compared to up to 1200 microm in normal teeth. This shows the retarded development of natal and neonatal teeth, because mineralization has not finished at the time of birth. In accordance with developmental age tooth structure and appearence are normal. In consideration of complications as Riga-Fede-disease, feeding problems, possibility of infection and hypermobility most of the time extraction is the treatment of choice, but in the interest of protecting the child this decision should be made carefully.

Breast↗

PubMed2006

[Dental erosion in children and adolescents: gastroenterologic background].

Reflux of acidic gastric secretions into the oral cavity may cause significant dental erosion. This gastro-oesophageal reflux has been shown to occur in children as well as in adults, and is often not accompanied by typical reflux symptoms. When symptoms are present the children may complain of heartburn, food regurgitation and epigastric pain. Current investigation involves ambulatory 24-hour oesophageal pH-measurements. In the case of exaggerated reflux, the main therapeutic option is medical acid suppression for several years. The pathogenesis, the diagnostic and therapeutic procedures as well as the importance of the cooperation between dentists and gastroenterologists are described and therapeutic advices are given.

Adolescent↗

PubMed2006

Treating open carious lesions in anxious children with ozone. A prospective controlled clinical study.

PURPOSE: To determine whether the treatment of dental caries with ozone was possible in apprehensive children and to ascertain whether ozone reverses caries in open single-surface lesions. Further, the influence of ozone on laser fluorescence was investigated. METHODS: 82 lesions in 28 children with at least two open single-surface lesions were assessed. The children were anxious and were judged by the referring dentist as non-treatable. For each test lesion, which was treated with ozone, a control lesion was left without ozone treatment. Hardness and laser fluorescence values were assessed and the changes for hardness and laser fluorescence values in the test lesion were compared with the values in the control lesion after 2, 4, 6, and 8 months. RESULTS: 94 percent of the children were treatable and 93% lost their dental anxiety. The hardness values improved significantly in the ozone-treated test lesions after 4, 6, and 8 months (P< 0.05) compared with baseline while the control lesions had no significant change in hardness at any recall interval. Comparing the differences between test and control teeth over time, the laser fluorescence values improved, however the improvement was not statistically significant (P> 0.05). The use of ozone resulted in an average reduction of 13% of the laser fluorescence values immediately after the ozone treatment.

Cariostatic Agents↗

PubMed2006

Erosive tooth wear: diagnosis, risk factors and prevention.

PURPOSE: To provide an overview on diagnosis, risk factors and prevention of erosive tooth wear, which is becoming an increasingly important factor when considering the long- term health of the dentition. RESULTS: Awareness of dental erosion by the public is still not widespread due to the cryptic nature of this slowly progressing condition. Smooth silky-glazed appearance with the absence of perikymata and intact enamel along the gingival margin, with cupping and grooving on occlusal surfaces are some typical signs of enamel erosion. In later stages, it is sometimes difficult to distinguish between the influences of erosion, attrition or abrasion during a clinical examination. Biological, behavioral and chemical factors all come into play, which over time, may either wear away the tooth surface, or potentially protect it. In order to assess the risk factors, patient should record their dietary intake for a distinct period of time. Based on these analyses, an individually tailored preventive program may be suggested to patients. It may comprise dietary advice, optimization of fluoride regimes, stimulation of salivary flow rate, use of buffering medicaments and particular motivation for non-destructive tooth brushing habits. The frequent use of fluoride gel and fluoride mouthrinse in addition to fluoride toothpaste offers the opportunity to minimize abrasion of tooth substance.

Acids↗

PubMed2005

Radiolucent lesion of an unerupted mandibular molar.

A coronal radiolucent lesion of an unerupted and partially developed mandibular second molar was coincidentally found during a routine radiographic orthodontic examination of a generally healthy 9-year old girl. The size of the lesion increased continuously during a 2-year observation period. Histologic examination after extracting the tooth proved the lesion to be an idiopathic external coronal resorption. In a review of the literature, we found no original research on the subject. However, the number of case reports suggests that idiopathic external coronal resorptions are quite common in young patients. Their etiology, however, remains unclear. The case history, histologic findings, differential diagnoses, and possible treatment approaches suggested in the literature are described.

Child↗

PubMed2005

Comparison of chemomechanical caries removal using Carisolv or conventional hand excavation in deciduous teeth in vitro.

OBJECTIVES: The purpose of the present study was to compare the efficacy of chemomechanical caries removal (Carisolv) to conventional hand excavation in deciduous teeth. METHODS: Twenty-two freshly extracted teeth with varying degree of caries were treated using both of these methods. One part of each caries lesion was prepared using the Carisolv method and the other part using conventional hand excavation. The third (middle) part was left untreated to serve as control. Histological preparations of each tooth were then made and examined in order to compare the quality of the preparations. Length and area of residual caries, microhardness of the dentine in each group and time needed for preparation were analysed. RESULTS: The results showed that there was no significant difference in the amount of residual caries in the cavity walls treated using the two methods. CONCLUSIONS: The Carisolv method was significantly more time consuming than conventional preparation using hand excavator. However, both methods removed caries efficiently.

Dental Caries↗

PubMed2005

Early loading of non-submerged titanium implants with a sandblasted and acid-etched surface. 5-year results of a prospective study in partially edentulous patients.

OBJECTIVES: The aim of this prospective cohort study was to evaluate the success rate of titanium screw-type implants with the sandblasted and acid-etched (SLA) surface loaded early, after 6 weeks of healing. MATERIAL AND METHODS: A total of 104 implants were inserted into posterior sites of 51 partially edentulous patients exhibiting bone densities of class I-III. After a healing period of 6 weeks, all implants were functionally loaded with cemented crowns or fixed partial dentures. The patients were recalled at 3, 12, 24, 36, 48 and 60 months for clinical and radiographic examination. RESULTS: One implant failed to integrate during healing, and three implants were lost to follow-up and were considered drop-outs. The remaining 100 implants showed favorable clinical and radiographic findings at the 5-year examination. The peri-implant soft tissues were stable over time; the mean probing depths and mean attachment levels did not change during the follow-up period. None of the radiographs exhibited signs of continuous peri-implant radiolucency, which confirmed ankylotic stability for all 100 implants. The measurement of the bone crest levels (DIB values) indicated stability as well. Based on strict success criteria, all 100 implants were considered successfully integrated, resulting in a 5-year success rate of 99%. CONCLUSION: This prospective study using an early loading protocol with 6 weeks of healing demonstrated that titanium implants with the SLA surface can achieve and maintain successful tissue integration with high predictability for at least 5 years of follow-up in selected patients and sites.

Crowns↗

PubMed2005

Erosion--chemical and biological factors of importance to the dental practitioner.

The intrinsic and extrinsic aetiology factors responsible for dental erosion are well understood as are the chemical events leading the initial mineral dissolution, softening and eventual loss of the dental surface. Of greatest importance are the pH, titratable acidity, phosphate and calcium concentration, fluoride content of the erosive challenge which determines the degree of saturation with respect to the tooth mineral, and thus the driving force for its dissolution. Of the biological modifying factors affecting the erosion process, the protective properties of saliva and its contribution to pellicle formation are considered of greatest importance. Unstimulated salivary flow rate and buffering capacity have been directly associated with dental erosion. The acquired pellicle has been shown to have a protective effect against acid erosion by acting as a diffusion barrier. There is considerable overlap between the aetiology of dental erosion and that of dentinal hypersensitivity. Patient education on the causes and prevention of dental erosion are essential to prevent progression. In addition to reducing or eliminating exposure to acidic soft drinks and juices, modified acid beverages with reduced potential to cause erosion can be recommended to patients. Frequent application of high concentration topical fluoride may be of some benefit in preventing further demineralisation and increase the abrasion resistance of erosion lesions.

Calcium↗