Reproducibility of habitual intercuspation in vivo

OBJECTIVES

The aim of this in vivo study was to investigate how reproducible individuals find their habitual intercuspation.

METHODS

A new type of highly accurate measuring procedure was involved using an intraoral optical scanning device (Cerec Bluecam). First, a pilot test investigated the accuracy of the procedure within a standardized setting. With regard to the in vivo study, fifteen participants with full dentition were selected. For each of these individuals, eight scans were taken both in the morning and in the afternoon. Furthermore, during each session, scans were taken both in horizontal and upright position. In order to compare this to ubiquitous used processes, plaster replicas of five individuals were investigated as well. The scans were analysed, and the differences in the position of the lower jaw were calculated by a specialized superimposition program (n=570 comparisons/OraCheck).

RESULTS

The results showed that there was no significant difference between the time of day and the position of the patient. The overall mean ± SD value for locating the habitual intercuspation was 42 ± 34 μm, however ranging from 22 ± 9 μm to 77 ± 58 μm for single individuals. On the other hand, the differences in positioning plaster replicas reached a mean of 135 ± 77 μm.

CONCLUSIONS

The reproducibility of the habitual intercuspation can be obtained under in vivo conditions by a newly developed and highly accurate measuring procedure. Individuals with full dentition show values in average of 42 μm.

CLINICAL SIGNIFICANCE

Determining the occlusal jaw relation is an important precondition in restorative dentistry and many methods are proposed for a proper occlusal registration. Although much is known about in vitro accuracy of these techniques, little is known how reproducible the habitual occlusal position itself is found between individuals.

Marginal adaptation of ceramic and composite inlays in minimally invasive mod cavities

OBJECTIVES

This study aims to evaluate the effect of a minimally invasive mesial-occlusal-distal (mod) preparation on the marginal adaptation of ceramic and composite inlays with the aim of saving sound dental substance.

MATERIALS AND METHODS

Class II mod cavities were prepared in 50 extracted human molars and randomly allocated to five groups (n = 10). In all groups, the mesial-proximal box margins were located in the dentin, 1 mm below the cementoenamel junction (CEJ), while the distal box margins were 1 mm above the CEJ. In groups A and B, conventional standard preparations with a divergent angle of α = 6° were prepared. In groups C, D, and E, minimally invasive standard preparations with a convergent angle of α = 10° were prepared. In groups A and D, composite inlays and, in groups B and C, ceramic inlays were fabricated (chairside economical restoration of esthetic ceramics (CEREC)) and adhesively inserted. In group E, a direct composite filling using the incremental technique was placed. Replicas were taken before and after thermomechanical loading (1,200,000 cycles, 50/5 °C, max. load 49 N). Marginal integrity (tooth-luting composite, luting composite-inlay) was evaluated by scanning electron microscopy (× 200). The percentage of continuous margins in the different locations was compared between and within groups before and after cycling, using ANOVA and Scheffé post hoc test.

RESULTS

After the thermomechanical loading, no significant differences were observed between the different groups with respect to the interface of luting composite-inlay. At the interface of tooth-luting composite for preparations involving the dentin, groups A and B behaved significantly better compared to the control group E, which in turn were not different to groups C and D.

CONCLUSION

Composite and ceramic inlays inserted in minimally invasive prepared mod cavities result in margins not different from those of inlays placed in conventional mod preparations. Direct composite filling margins, however, were inferior to those attained by conventional indirect restorations.

CLINICAL RELEVANCE

Minimally invasive preparations for mod inlays with undercuts show marginal adaptation equal to that of conventional inlay preparation design.

Influence of scanning strategies on the accuracy of digital intraoral scanning systems

The digital intraoral impression is a central part in today's CAD/CAM dentistry. With its possibilities, new treatment options for the patient is provided and the prosthetic workflow is accelerated. Nowadays, the major issue with intraoral scanning systems is to gain more accuracy especially for larger scan areas and to simplify clinical handling for the dentist. The aim of this study was to investigate different scanning strategies regardingtheir accuracy with full arch scans in an in-vitro study design. A reference master model was used for the digital impressions with the Lava COS, the Cerec Bluecam and a powderfree intraoral scanning system, Cadent iTero. The trueness and precision of each scanning protocol was measured. Lava COS provides the a trueness of 45.8 microm with the scanning protocol recommended from the manufacturer. A different scanning protocol shows significantly lower accuracy (trueness +/- 90.2 microm). Cerec Bluecam also benefits from an optimal scanning protocol with a trueness of +/- 23.3 microm compared to +/- 52.5 microm with a standard protocol. The powderfree impression system Cadent iTero shows also a high accurate full-arch scan with a trueness of +/- 35.0 microm and a precision of +/- 30.9 microm. With the current intraoral scanning systems, full arch dental impressions are possible with a high accuracy, if adequate scan strategies are used. The powderfree scanning system provides the same level of accuracy compared to scanning systems with surface pretreatment.

3D monitoring and quality control using intraoral optical camera systems

The quality of intraoral scanning systems is steadily improving, and they are becoming easier and more reliable to operate. This opens up possibilities for routine clinical applications. A special aspect is that overlaying (superimposing) situations recorded at different times facilitates an accurate three-dimensional difference analysis. Such difference analyses can also be used to advantage in other areas of dentistry where target/actual comparisons are required. This article presents potential indications using a newly developed software, explaining the functionality of the evaluation process and the prerequisites and limitations of 3D monitoring.

Skin prick test and specific serum IgE in the diagnostic evaluation of suspected cow's milk and hen's egg allergy in children: does one replace the other?

BACKGROUND

The measurement of specific serum immunoglobulin E (sIgE) and the skin prick test (SPT) are accepted tools in the diagnostic work-up of suspected food allergy. Often only one of the methods is used to determine sensitization; however, it is still under debate whether these two methods can be used interchangeably.

OBJECTIVES

To investigate the concordance of SPT and sIgE serum assays with regard to suspected food allergy.

METHODS

In 395 children referred to our clinic with suspected cow's milk allergy and in 268 children with suspected hen's egg allergy specific immunoglobulin E (IgE) was measured, a SPT and an oral food challenge performed. A weal size ≥ 3 mm and sIgE ≥ 0.35 kU/L were considered positive. The weal size of the SPT and the level of food-specific IgE were tested for correlation for each allergen.

RESULTS

Of the 395 (23%) children orally challenged with cow's milk, 92 showed no corresponding results for SPT and sIgE as either positive or negative. For hen's egg, in 27 of 268 (10%) children differing test results for SPT and sIgE in serum were obtained. Moreover, regarding the quantitative values for sIgE and SPT in children with or without clinically relevant food allergy, sIgE and SPT correlated badly.

CONCLUSIONS

The concordance between SPT and sIgE is surprisingly low for cow's milk and hen's egg on an individual basis. Therefore, the tests should not be used interchangeably. Especially in children who receive a negative test result the alternative test should also be used. Furthermore, our data indicate again that oral food challenges are still the method of choice to diagnose food allergies.

A new concept for the integration of dynamic occlusion in the digital construction process

Major advances have been made in dental computer-assisted design and manufacturing (CAD/CAM) technology in recent years. New developments in intraoral optical scanning systems make it possible to rapidly obtain three-dimensional images and measurements of the jaw and entire quadrants, including the prepared teeth, neighboringteeth, and opposing dentition. In addition, the static relationship of the maxillary and mandibular teeth to one another can easily be determined by means of intraoral bite registrations or buccal scans. This information is the starting point for the implementation of digital occlusal surface design and surface reconstruction. Here, too, the knowledge-based concept of biogenerics has crystallized into a new method in which restoration proposals suitable for each individual case are automatically computed by the software. Consequently, the time required to manually edit the digital model has been significantly reduced or completely eliminated. In its current form, the digital workflow still lacks a strategy for integrating the dynamic occlusion into the restoration design with high precision and in atime-saving manner. The preliminary results of new digital concepts and approaches to solving this problem will be presented in this article.

Full arch scans: conventional versus digital impressions--an in-vitro study

The digital intraoral impression has become a central part of the CAD/CAM technique. The objective of the present study was to compare the accuracy (trueness and precision) of digital impressions of the full arch with that of conventional impressions on the in-vitro model. For this purpose, a master model was acquired with a new reference scanning process, the measuring trueness of which was +/- 4.1 microm and the precision +/- 2.5 microm. On the one hand, conventional impressions and then plaster models (n = 5) were produced from this master model, and on the other hand, digital impressions were made with the Cerec AC Bluecam and the Lava COS system (each n = 5). The plaster models were also scanned with the reference scanner. The available data records were superimposed and the differences determined. The deviation from the master model defines the trueness of the impression method. The deviations of the models among one another demonstrate the precision of the method. The trueness of the impressions was 55 +/- 21.8 microm in the conventional impression group, for digital impressions with Cerec Bluecam it was 49 +/- 14.2 microm and for digital impressions with Lava COS 40.3 +/- 14.1 microm. The precision was 61.3 +/- 17.9 microm for conventional impression with Impregum, 30.9 +/- 7.1 microm for digital impression with the Cerec Bluecam and 60.1 +/- 31.3 microm for digital impression with Lava COS. These in-vitro results show that accuracy of the digital impression is similar to that of the conventional impression. These results will have to be confirmed in further clinical studies.

Digital 3-D implant planning: Cerec meets Galileos

Prosthetically based implant planning is necessary so that implants are set expediently and correctly during surgery. A clinical case is presented to describe how this can be performed today purely digitally. Prosthetic planning was undertaken with the Cerec CAD/CAM system. The data record created was transferred and superimposed on a CBCT 3-D radiograph. The position of the implant was planned taking the prosthetic planning into account.

Accuracy testing of a new intraoral 3D camera

Surveying intraoral structures by optical means has reached the stage where it is being discussed as a serious clinical alternative to conventional impression taking. Ease of handling and, more importantly, accuracy are important criteria for the clinical suitability of these systems. This article presents a new intraoral camera for the Cerec procedure. It reports on a study investigating the accuracy of this camera and its potential clinical indications. Single-tooth and quadrant images were taken with the camera and the results compared to those obtained with a reference scanner and with the previous 3D camera model. Differences were analyzed by superimposing the data records. Accuracy was higher with the new camera than with the previous model, reaching up to 19 microm in single-tooth images. Quadrant images can also be taken with sufficient accuracy (ca 35 microm) and are simple to perform in clinical practice, thanks to built-in shake detection in automatic capture mode.

Fit of surgical guides--manufactured by InLab 3D

Based on an exclusively virtual implant planning and positioning concept, the fit of surgical-guide-like workpieces was evaluated in an in-vitro pilot study, manufactured with the InLab 3D system. From 85 maxillary casts, 8 were randomly selected. The first right maxillary incisor was removed. After optical impression of the maxillary anterior teeth, a drilling template was designed by the use of the InLab software, version 3.0. The mode "bridge" "dental database" was applied. The guidance was milled from a methacrylate block and braced on the adjacent teeth. After milling, they were checked for proper seat (without rocking). The discrepancies between the inner surface of the template and the opposing tooth surface was shown with a silcone based material, which rested on the casts after removing the template. The difference between the thickness of the silicone layer and the subjacent tooth surface was measured with a high resolution scanner. In order to characterize the fit of the 8 workpieces the average mean, average maximum and average minimum values of the fit were calculated in the buccal, incisal and palatinal area using the program Match 3D (W. Gloger, LMU): average mean: buccal: 65 microm; incisal: 116 microm; palatinal: 94 microm; average maximum: buccal: 162 microm; incisal: 202 microm; palatinal:190 microm; average minimum: buccal: 5 microm; incisal: 14 microm; palatinal: 15 microm. In the present study it was possible to produce drilling templates with the already commercially available InLab system. The results were presented at the Annual Meeting of the German Society of Computerized Dentistry 2007 as a short presentation.

Evaluation for the fully automatic inlay reconstruction by means of the biogeneric tooth model

Length measurements and descriptive characterizations were previously the sole reference points for describing the morphology of the occlusal surface. For computerized methods in dentistry, this is not sufficient for producing a data record. So far, the literature has reported no solutions. With the aid of a tooth library containing three-dimensionally measured occlusal surfaces free of caries and abrasion, a mathematical model was produced to describe a certain type of tooth by reference to a few parameters, taking account of functional and biologically relevant structures. This biogeneric tooth model was tested on 27 different inlay situations. The results show that fully automatic reconstruction was possible in all cases. The deviations of the reconstructions from the original tooth surface were on average around 150 microm. Furthermore, the influence of different parameters on the mathematical model was examined. Here, combinations that guarantee the best possible reconstruction for many situations could be found. The visual evaluation and the metric comparison of the reconstructions among one another illustrate the great flexibility of the biogeneric tooth model. With the aid of the biogeneric tooth model, there is the possibility of reconstructing the occlusal surfaces of dental restorations by CAD/CAM processes fully automatically, taking account of morphological and functional criteria. Further studies are needed to show to what extent the inclusion of degree of abrasion, antagonist and adjacent teeth delivers the desired results in the whole spectrum of clinical cases.

A new mathematical process for the calculation of average forms of teeth

STATEMENT OF PROBLEM

Qualitative visual inspections and linear metric measurements have been predominant methods for describing the morphology of teeth. No quantitative formulation exists for the description of dental features.

PURPOSE

The aim of this study was to determine and validate a mathematical process for calculation of the average form of first maxillary molars, including the general occlusal features.

MATERIAL AND METHODS

Stone replicas of 174 caries-free first maxillary molar crowns from young patients ranging from 6 to 9 years of age were measured 3-dimensionally with a laser scanning system at a resolution of approximately 100,000 points. Then, the average tooth was computed, which captured the common features of the molar's surface quantitatively. This new method adapts algorithms both from computer science and neuroscience to detect and associate the same features and same surface points (correspondences) between 1 reference tooth and all other teeth. In this study, the method was tested for 7 different reference teeth. The algorithm does not involve any prior knowledge about teeth and their features.

RESULTS

Irrespective of the reference tooth used, the procedure yielded average teeth that showed nearly no differences (less than +/-30 microm).

CONCLUSION

This approach provides a valid quantitative process for calculating 3-dimensional (3D) averages of occlusal surfaces of teeth even in the event of a high number of digitized surface points. Additionally, because this process detects and assigns point-wise feature correspondences between all library teeth, it may also serve as a basis for a more substantiated principal component analysis evaluating the main natural shape deviations from the 3D average.

Anaphylactic reactions in children--a questionnaire-based survey in Germany

BACKGROUND

Severe anaphylactic reactions are medical emergencies requiring immediate recognition and treatment. Despite this, little is known on their clinical features, especially in infants and children.

OBJECTIVE

To evaluate trigger factors, patterns of clinical reaction, site of occurrence and treatment modalities of reported reaction in infants and children below 12 years of age in Germany.

METHODS

Paediatricians throughout Germany were asked by questionnaire to report accidental anaphylactic reactions over the previous 12 months. Severity of reported reactions was classified in grades I-IV according to reported symptoms.

RESULTS

Hundred and three cases of anaphylaxis were evaluated. Median age was 5 years, 58% were boys. Site of occurrence was the child's home in the majority of cases (58%). Foods were the most common causative allergen (57%), followed by insect stings (13%) and immunotherapy (SIT) (12%); in 8% anaphylactic agent was unknown. Among foods, peanuts and tree nuts were the most frequent allergens (20% of food allergens in each case). Severe reactions with cardiovascular involvement occurred in 24% of cases. No fatal reaction was observed. Recurrent episodes of anaphylaxis were reported in 27% of cases, half of these caused by the same allergen again. For treatment, 20% of children received adrenaline, in 8% of cases intravenously. Thirty-six per cent of patients with grade-IV reactions received adrenaline, 24% intravenously. In 17% of all children an adrenaline self-injector was prescribed after the episode.

CONCLUSION

Our data: (i) shows an uncertainty of physicians in diagnosing anaphylaxis, (ii) reveals remarkable under-treatment of the majority of children with anaphylaxis, (iii) reflects the need for guidelines and training for physicians in managing children with anaphylaxis and (iv) should encourage the development of self-management programmes for patients and families.

Specific oral tolerance induction with food in children: transient or persistent effect on food allergy?

BACKGROUND

The standard treatment of food allergy is elimination of the incriminated food from the diet. Specific oral tolerance induction (SOTI) seems to be a promising approach for a causal treatment; however, it is unclear whether the tolerance achieved is transient or persistent. We report on a subset of three patients of a larger ongoing study who were treated successfully with SOTI treatment, but experienced a secondary loss of tolerance after a period of allergen avoidance.

METHODS

The patients suffered from IgE-mediated allergy either to cow's milk (CM) (patient A) or hen's egg (HE) (patients B and C), confirmed by double-blind, placebo-controlled food challenge (DBPCFC). SOTI treatment was performed at home on a daily basis until tolerance to a maximum of 250 ml CM or 4.5 g lyophilized HE protein was achieved. The daily maintenance dose was 100 ml CM or 2.5 g HE protein.

RESULTS

Patients A, B and C reached tolerance to the maximum dose after 37, 41 and 52 weeks, respectively. According to the protocol, patients A and B performed a strict secondary elimination diet for 2 months prior to a follow-up DBPCFC after a maintenance phase of 27 and 39 weeks, respectively. Patient C discontinued treatment for 2 days after 4 weeks on the maintenance dose. Despite previous tolerance, on re-exposure to the allergen all patients experienced moderate systemic allergic reactions.

CONCLUSIONS

We conclude that SOTI can induce transient tolerance in food allergy, but does not necessarily lead to its permanent abrogation. Regular allergen intake seems necessary to maintain the established tolerance.

The predictive value of the skin prick test weal size for the outcome of oral food challenges

BACKGROUND

The skin prick test (SPT) is regarded as an important diagnostic measure in the diagnostic work-up of food allergy. Objective To evaluate the diagnostic capacity of the SPT in predicting the outcome of oral food challenges, and to determine decision points for the weal size and the skin index (SI) that could render double-blind, placebo-controlled food challenges unnecessary.

METHODS

In 385 children (median age 22 months), 735 controlled oral challenges were performed with cow's milk (CM), hen's egg (HE), wheat and soy. Three hundred and thirty-six of 385 (87%) children suffered from atopic dermatitis. SPT was performed in all children. Diagnostic capacity, receiver-operator characteristics (ROC) curves and predictive decision points were calculated for the mean weal size and the calculated SI.

RESULTS

Three hundred and twelve of 735 (43%) oral food challenges were assessed to be positive. Calculation of 95% and 99% predicted probabilities using logistic regression revealed predictive decision points of 13.0 and 17.8 mm for HE, and 12.5 and 17.3 mm for CM, respectively. However, using the SI, the corresponding cut-off levels were 2.6 and 3.7, respectively, for HE, and 2.7 and 3.7 for CM. For wheat, 95% and 99% decision points of 2.2 and 3.0 were found in children below 1 year of age.

CONCLUSION

Predictive decision points for a positive outcome of food challenges can be calculated for HE and CM using weal size and SI. They may help to avoid oral food challenges.

Utility of the ratio of food-specific IgE/total IgE in predicting symptomatic food allergy in children

BACKGROUND

Double-blind, placebo-controlled food challenges are time-consuming, expensive and not without risk to patients. Therefore, an in vitro test that could accurately diagnose food allergy would be of great value.

OBJECTIVE

To evaluate the utility of the ratio of specific immunoglobulin E (IgE)/total IgE compared with specific IgE (sIgE) alone in predicting symptomatic food allergy.

METHODS

We retrospectively analysed 992 controlled oral food challenges performed in 501 children (median age 13 months). The ratio of sIgE/total IgE was calculated and tested for correlation with the outcome of food challenges. Receiver operator characteristics (ROC)-curves were performed; predicted probabilities and predictive decision points were calculated.

RESULTS

A significant correlation was found between the ratio and the outcome of food challenges for cow's milk (CM), hen's egg (HE), and wheat, but not for soy. The ROC and predicted probability curves as well as sensitivity and specificity of the decision points of the ratio were similar to those of sIgE levels for CM, HE and wheat.

CONCLUSION

In view of the greater effort needed to determine the ratio, without benefit compared with the sIgE alone, the calculation of the ratio of sIgE/total IgE for diagnosing symptomatic food allergy offers no advantage for CM, HE, wheat or soy. For the majority of cases controlled oral food challenges still remain the method of choice.

Controlled oral food challenges in children--when indicated, when superfluous?

The diagnostic work-up of suspected food allergy includes the skin prick test (SPT), the measurement of food specific immunoglobulin E (IgE) antibodies using serologic assays, and more recently the atopy patch test (APT). For specific serum IgE and the SPT, decision points have been established for some foods allowing prediction of clinical relevance in selected cases. The APT may be helpful, especially when considered in combination with defined levels of specific IgE. Controlled oral food challenges still remain the gold standard in the diagnostic work-up of children with suspected food allergy. Most food allergic children will lose their allergy over time. As there is no laboratory parameter, which can accurately predict when clinical tolerance has been developed, controlled oral food challenges are the measure of choice. In this article, the current knowledge of predictors for the outcome of oral food challenges is reviewed and proposals for the daily practical work-up in the case of suspected food related clinical symptoms are presented.

Utility of the ratio of food-specific IgE/total IgE in predicting symptomatic food allergy in children

BACKGROUND

Double-blind, placebo-controlled food challenges are time-consuming, expensive and not without risk to patients. Therefore, an in vitro test that could accurately diagnose food allergy would be of great value.

OBJECTIVE

To evaluate the utility of the ratio of specific immunoglobulin E (IgE)/total IgE compared with specific IgE (sIgE) alone in predicting symptomatic food allergy.

METHODS

We retrospectively analysed 992 controlled oral food challenges performed in 501 children (median age 13 months). The ratio of sIgE/total IgE was calculated and tested for correlation with the outcome of food challenges. Receiver operator characteristics (ROC)-curves were performed; predicted probabilities and predictive decision points were calculated.

RESULTS

A significant correlation was found between the ratio and the outcome of food challenges for cow's milk (CM), hen's egg (HE), and wheat, but not for soy. The ROC and predicted probability curves as well as sensitivity and specificity of the decision points of the ratio were similar to those of sIgE levels for CM, HE and wheat.

CONCLUSION

In view of the greater effort needed to determine the ratio, without benefit compared with the sIgE alone, the calculation of the ratio of sIgE/total IgE for diagnosing symptomatic food allergy offers no advantage for CM, HE, wheat or soy. For the majority of cases controlled oral food challenges still remain the method of choice.

The predictive value of specific immunoglobulin E levels in serum for the outcome of oral food challenges

BACKGROUND

Specific serum IgE is considered as one of the important diagnostic measures in the diagnostic work-up of food allergy.

OBJECTIVE

To evaluate the role of specific serum IgE in predicting the outcome of oral food challenges, and to determine threshold concentrations of specific serum IgE that could render double-blind, placebo-controlled food challenges unnecessary.

METHODS

In 501 children (median age 13 months), 992 controlled oral challenges were performed with cow's milk (CM), hen's egg (HE), wheat and soy. 440/501 (88%) children suffered from atopic dermatitis. For all children, specific IgE concentrations in serum were determined. Sensitivity, specificity, positive and negative predictive values, receiver operator characteristics-curves as well as predictive decision points were calculated.

RESULTS

Four hundred and forty-five out of 992 oral food challenges with allergens were assessed as positive. Sensitivity of specific serum IgE was 97% for HE, 83% for CM, 69% for soy, and 79% for wheat. Specificity was 51% for HE, 53% for CM, 50% for soy, and 38% for wheat. Calculating 90%, 95% and 99% predicted probabilities using logistic regression revealed predictive decision points of 6.3, 12.6, and 59.2 kU/L for HE, respectively. Subdividing our children in those of below or above 1 year of age resulted in a markedly different predicted probability for HE. For CM, only the 90% predicted probability (88.8 kU/L) could be calculated. No decision points could be determined for CM, wheat and soy.

CONCLUSION

In general, specific serum IgE levels showed a correlation with the outcome of positive oral food challenges for CM and HE. Meaningful predictive decision points can be calculated for HE, which may help to avoid oral food challenges in some cases. However, data need to be ascertained for each allergen separately. Furthermore, the age of the patient population under investigation must also be taken into account.