[Preprosthetic orthodontic treatments]. / Preprothetische orthodonti- sche behandelingen.

The objective of a preprosthetic orthodontic treatment is to position the teeth in such a way that a treatment with (fixed) dental prostheses is made possible or simplified or to affect the result of this treatment positively. Conceivable preprosthetic orthodontic treatments are: correcting primary orthodontic anomalies, closing or reducing interdental spaces and correcting the migration of teeth. In the case of unfavourable maxillomandibular relations, a preprosthetic surgical treatment is usually needed together with a preprosthetic orthodontic treatment. For children with agenesis and/or early loss of teeth and/or aberrant morphology of teeth, a treatment with fixed dental prostheses, either implant-supported or not, may be indicated after the tooth development or in some cases earlier. Until that time, preprosthetic orthodontic treatments may be indicated to offer an aesthetically sound provisional solution and to achieve optimal teeth positions for the final fixed dental prostheses.

A comparison of finite element analysis with in vitro bond strength tests of the bracket-cement-enamel system.

The aim of this study was to determine the in vitro shear bond strength (SBS) and tensile bond strength (TBS) of 45 metal brackets bonded with Transbond XT to bovine enamel. The SBS was determined by loading the short and the long sides of the bracket base. Testing took place after storage of the specimens for 72 hours in water at 37°C. Fractures were analysed with the adhesive remnant index (ARI) and scanning electron microscope (SEM). The stresses in the system were analysed with finite element (FE) analysis models of the experimental set-up to identify the initial fracture point and the stress distribution at fracture. Statistical analysis of bond strengths was performed using analysis of variance (ANOVA) and the Tukey's post hoc test (P < 0.05). The ARI scores were analysed using Kruskal-Wallis one-way ANOVA on ranks. ANOVA showed significant differences between the three experiments. Loading the short side of the bracket resulted in the highest average bond strength. Tensile loading gave the lowest results. FE models supported the bond strength findings and SEM. FE analysis revealed peak stresses in the cement during loading, confirming that shear testing is sensitive to loading angles. The stress distribution over the bracket-cement-enamel system is not homogeneous during loading. Fractures are initiated at peak stress locations. As a consequence, the size of the bonding area is not predictive of bond strength. The bracket design and the mode of loading may be of greater relevance.

[Satisfaction among parents about treatment-teams of childeren with a cleft lip and/or palate]. / Tevredenheid van ouders over het schisisteam.

In this contribution, the results are presented of a study of the degree of satisfaction among parents of children with a cleft lip and/or palate with care provided for their children. A questionnaire with declarative statements and a number of open questions relevant to treatment received was sent to the 213 members of the workgroup Cleft Lip and/or Palate of the society of the motor-handicapped and their parents. In addition, parents were asked to give a grade for the team who treated their child. The results (response n = 101) indicate that, with respect to a number of aspects, there are differences in satisfaction concerning the care which was provided among the 5 treatment-teams with the most responses. The average grade given by parents for the care provided by Dutch cleft lip and/or palate teams was 7.4. Parents would like to be better informed and treated in a friendlier way.

Oral health-related quality of life of children with craniofacial conditions.

OBJECTIVE: Evaluation of the Dutch Child Oral Health Impact Profile (COHIP), assessing the level of concordance between parents and children. The internal consistency and the predictive validity of the COHIP for self-reported general health were examined. METHODS: Sample size was 35 pairs of parents and children age 11 to 14 with craniofacial conditions. Cronbach alphas were calculated and the level of concordance between parents and children was studied using t tests and intraclass correlations. Predictive validity was assessed using Pearson correlations and linear regression analyses. RESULTS: The COHIP and its subscales, except for one, had satisfactory to high Cronbach alphas (.59 to .94). Parents and children did not differ significantly. Correlations between parents and children were high (.62 to .91). Only "Oral symptoms" proved to be a significant predictor of general health, but only in the parent sample. CONCLUSIONS: In spite of the high level of concordance found, proxy reports have to be considered complementary to the reports of the children themselves. The Dutch version of the COHIP performs adequately, but could use some further psychometric evaluation and revision. It does not seem advisable to use the subscales separately as predictors in the same regression model, since they are strongly intercorrelated. For use in craniofacial patients, further validation is needed on a larger sample and some items need to be revised or removed. Finally, given the small number of cases, conclusions must be drawn with caution.

[Attitudes towards orthodontic treatment. A comparison of treated and untreated adolescents]. / Attituden ten aanzien van orthodontische behandeling. Een vergelijking tussen behandelde en niet-behandelde jongeren.

Dutch adolescents' attitudes towards orthodontic treatment and the determinants of these attitudes are unknown. The aim of the present study was to evaluate treated and untreated adolescents' attitudes towards orthodontic treatment, and to examine possible determinants of these attitudes. Previously treated adolescents were found to have a more positive attitude towards orthodontic treatment than untreated adolescents. Age, but not gender, was found to be a significant predictor for their general attitude towards orthodontic treatment. Consequently, it was concluded that attitudes were not determined by one specific aspect, but by a combination of several determinants.

The reliability and validity of the Index of Complexity, Outcome and Need for determining treatment need in Dutch orthodontic practice.

The Index of Complexity, Outcome and Need (ICON), based on international opinion, has been proposed as a multipurpose occlusal index. The aim of this study was to validate the ICON for treatment need in the Netherlands by relating it to Dutch orthodontic opinion. Furthermore, the reliability of this index was explored, for both a calibrated orthodontist and non-calibrated orthodontists. A sample of 102 patients was chosen which represented the actual distribution of severity of malocclusion experienced by orthodontists in every day practice. The ICON was scored, based on complete patients records of those 102 patients, by an examiner calibrated in the use of this index. The results were compared with the opinion about treatment need of seven Dutch orthodontists - the 'gold standard'. Nine non-calibrated orthodontists also scored the ICON for 49 patients. The intra-examiner agreement of both the non-calibrated and the calibrated orthodontists was moderate to high [0.52-0.86 and 0.89, respectively, measured with the Intraclass Correlation Coefficient (ICC)]. The inter-examiner agreement of the ICON score of the nine orthodontists was moderate measured with the single estimate of the ICC (0.60), and high measured with the average estimate (0.93). Spearman's correlation coefficient between the ICON score (calibrated) and the gold standard was sufficient: 0.78. The sensitivity and specificity were 1 and 0.36, respectively. The best compromise between sensitivity and specificity was at a cut-off point of 52, instead of the international ICON cut-off point of 43. There was a significant difference in ICON score between the non-calibrated orthodontists and the calibrated orthodontist, mainly based on the Aesthetic Component (AC) of the Index of Orthodontic Treatment Need (IOTN). It can be concluded that the ICON needs to be adjusted when used to determine treatment need in the Dutch orthodontic population.

The influence of force magnitude on intrusion of the maxillary segment.

The purpose of this study was to determine whether the magnitude of intrusive force to the maxillary incisors influences the rate of incisor intrusion or the axial inclination, extrusion, and narrowing of the buccal segments. Twenty patients between the ages of nine and 14 years who needed at least two mm of maxillary incisor intrusion were assigned to one of two equal groups. In group 1 patients, the teeth in the maxillary anterior segment were intruded using 40 g, whereas in group 2 patients, 80 g was used. Records were taken from each patient at the beginning and end of intrusion. There was no statistically significant difference between the 40- and 80-g groups in the rate of incisor intrusion, or the amount of axial inclination change, extrusion, and narrowing of the buccal segments.

The relation between the point of force application and flaring of the anterior segment.

The purpose of this study was to determine whether application of an intrusive force by an intrusion arch at the distal wings of the lateral incisor brackets causes a change in the axial inclination of the anterior segment. Maxillary incisor intrusion was performed, and records were taken from 40 adolescent patients at the beginning and end of intrusion. Intrusion of the maxillary anterior segment caused a statistically significant mean increase in axial inclination of the central incisor of 8.74 degrees. The following correlations were investigated and found not statistically significant. The correlation between the (1) distance from the point of force application to the center of resistance at the start of intrusion and the change in axial inclination of the incisor, (2) distance from the point of force application to the center of resistance at the start of intrusion and the change in distance from the incisal edge to the distal side of the first molar, (3) distance from the point of intrusive force application to the center of resistance at the start of intrusion and at the end of intrusion, (4) distance from the point of intrusive force application to the center of resistance at the start of intrusion and the change in this distance between start and end of intrusion, and (5) amount of intrusion and the change in axial inclination.

The influence of accelerating the setting rate by ultrasound or heat on the bond strength of glass ionomers used as orthodontic bracket cements.

Conventional glass ionomer cements (GICs) may be a viable option for bracket bonding when the major disadvantages of these materials, such as the slow setting reaction and the weak initial bond strength, are solved. The aim of this in vitro study was to investigate the influence of ultrasound and heat application on the setting reaction of GICs, and to determine the tensile force to debond the brackets from the enamel. A conventional fast-setting GIC, Fuji IX Fast, and two resin-modified glass ionomer cements (RMGICs), Fuji Ortho LC and Fuji Plus, were investigated. Three modes of curing were performed (n = 10): (1) according to the manufacturer's prescription, (2) with 60 seconds application of heat, or (3) with 60 seconds application of ultrasound. The tensile force required to debond the brackets was determined as the tension 15 minutes after the start of the bonding procedure. The mode of failure was scored according to the Adhesive Remnant Index (ARI) to establish the relative amount of cement remnants on the enamel surface. Curing with heat and ultrasound shortened the setting reaction and significantly (P < 0.05) increased the bond strength to enamel. The ARI scores showed an increase for all materials after heat and ultrasound compared with the standard curing method, most notably after heat application.

[Care for children born with cleft lip, jaw and/or palate]. / Zorgverlening aan kinderen met cheilo-, gnatho- en/of palatoschisis.

The number of children with cleft lip and/or palate needing care in and the possibilities of care delivering to these patients by muitidisciplinary teams are described. The data are compared with data from other European countries. The improvements in quality of care and patients are elucidated by research data.

Dental age in Dutch children.

Dental age was studied in a sample of 451 Dutch children (226 boys and 225 girls) according to the method of Demirjian. They were born between 1972 and 1993 and were between 3 and 17 years of age at the time a dental pantomogram (DPT) was obtained. All children were placed in the age group closest to their chronological age. All 451 DPTs were scored by one examiner. A subset of 52 DPTs was scored by a second examiner and the intra-class correlation coefficient (ICC) and Cohen's kappa were calculated. The ICC was 0.99 and Cohen's kappa 0.68. Boys and girls were analysed separately.A significant difference was found between chronological age and dental age. On average, the Dutch boys were 0.4 years and the girls 0.6 years ahead of the French-Canadian children analysed by Demirjian. Therefore, the French-Canadian standards were not considered suitable for Dutch children. New graphs for the Dutch population were constructed using a logistic curve with the equation Y = 100*{1/(1 + e(-alpha(x - x0)))} as a basis. The 90 per cent confidence interval was calculated. To determine whether the logistic curve was correct, a residual analysis was carried out and scatter plots of the differences were made. The explained variance was 93.9 per cent for the boys and 94.8 per cent for the girls. Both the residual analysis and the scatter plots indicated that the logistic curve was appropriate for use with Dutch children. In addition to the graphs, tables were produced which transfer the maturity scores calculated by the method of Demirjian into Dutch dental age.

Surgically assisted rapid maxillary expansion (SARME): a review of the literature.

Transverse maxillary hypoplasia, in adolescents and adults, is frequently seen in non-syndromal and syndromal patients including cleft patients. In skeletally matured patients, the uni- or bilateral transverse hypoplasia can be corrected by means of a surgically assisted rapid maxillary expansion. The treatment is a combination of orthodontics and surgical procedures and provides dental arch space for alignment of teeth. The procedure also causes a substantial enlargement of the maxillary apical base and of the palatal vault, providing space for the tongue for correct swallowing and thus preventing relapse. In addition, a distinct subjective improvement in nasal breathing associated with enlargement of the nasal valve towards normal values is seen with an increase of nasal volume in all compartments. In this article we give a review on surgically assisted rapid maxillary expansion. We conclude that there is no consensus in the searched literature regarding either the surgical technique, the type of distractor used (tooth-borne or bone-borne), the existence, cause and amount of relapse and whether or not overcorrection is necessary. A proposal for a prospective randomized patient study in order to find answers to the lacunas in knowledge regarding this treatment is done.

Caries prevalence measured with QLF after treatment with fixed orthodontic appliances: influencing factors.

Caries prevalence on the buccal surfaces of teeth in orthodontic patients was determined with QLF and visual examination immediately after removal of fixed appliances. The number of lesions found by QLF far outnumbered that found by visual examination, but the distribution pattern was similar. 97% of all subjects and on average 30% of the buccal surfaces in a person were affected. On average, in males 40% of surfaces and in females 22% showed white spots (p < 0.01). Caries prevalence was lower (p < 0.01) in incisors and cuspids than in molars and premolars. A positive correlation with caries prevalence was found for the bleeding scores 6 weeks after debonding and lactobacillus counts before debonding. Mutans streptococci counts, age, treatment duration, socioeconomic status and dietary habits showed no correlation with caries prevalence.

Outcome of treatment of Class II malocclusion by intraoral mandibular distraction.

Our aim was to find out long-term results of treatment in patients treated orthodontically and by mandibular distraction osteogenesis. Data on duration of treatment, costs, and results of 26 patients (13 girls and 13 boys) with a mean age of 15 years were analysed. The preoperative cephalograms were compared with those taken at the last follow-up visit. There was a significant reduction in duration of treatment when patients were treated without a first phase that included functional appliances. The differences in costs of orthodontic treatment were not significant. The costs of the operation for distraction were significantly higher compared to BSSO, mainly because of the costs of the distraction devices. Comparison of the cephalograms showed a significant increase in SNB angle, Wits value, ANB angle, overjet, and overbite. The Y-axis, MP/S, and SpP/MP angle increased. Orthodontic treatment and distraction of the mandible was a successful, but more expensive, treatment.

Human jaw muscle strength and size in relation to limb muscle strength and size.

The aim of the present study was to investigate to what extent general factors (e.g. genotype, hormones) and factors at the craniofacial level (e.g. craniofacial size, jaw muscle architecture) contribute to the size and strength of the jaw muscles. A strong relationship of jaw muscle size and strength with that of other muscles would argue for general influences, whereas a weak relationship would argue for craniofacial influences. In 121 adult individuals, moments of maximal bite force, arm flexion force and leg extension force were measured. In addition, thicknesses of jaw muscles, arm flexor muscles and leg extensor muscles were measured using ultrasound. Relationships were assessed by using a principal component analysis. In females, one component was found in which all force moments were represented. Bite force moment, however, loaded very low. In males, two components were found. One component loaded for arm flexion and leg extension moments, the other loaded for bite force moments. In both females and males, only one component was found for the muscle thicknesses in which all muscle groups loaded similarly. It was concluded that the size of the jaw muscles was significantly related to the size of the limb muscles, suggesting that they were both subject to the same general influences. Maximal voluntary bite force moments were not significantly related to the moments of the arm flexion and leg extension forces, suggesting that besides the general influence on the muscle size, variation in bite force moment was also influenced by local variables, such as craniofacial morphology.

The role of a high pull headgear in counteracting side effects from intrusion of the maxillary anterior segment.

Intrusion of incisors is often the preferred treatment of a deep overbite. This study focuses on deep overbite correction by intrusion of maxillary incisors. The purpose of this study is to determine whether high-pull headgear wear can prevent steepening of the buccal segment, extrusion of the buccal segment, maintain arch width, and increase the rate of incisor intrusion. The number of patients needed for this study was calculated to be 20. Patients were between nine and 14 years of age and assigned to one of two groups. In each group, intrusion of maxillary incisors was performed. Patients in one group wore a high-pull headgear at night, and patients in the other group did not. For each patient, a lateral head film, impressions with a wax bite in centric occlusion, and intraoral photographs were taken at the beginning and end of intrusion. This study demonstrated that high-pull headgear had no effect on steepening and extrusion of the buccal segments or on the rate of intrusion but did have an effect on narrowing of the buccal segments. By performing intrusion as described in this study, no statistically significant side effects were observed in the buccal segments, whereas a statistically significant amount of incisor intrusion of 2.24 mm in the no-headgear group and 2.37 mm in the headgear group was observed.

[Ectopic eruption of the maxillary first permanent molar]. / Ectopische eruptie van de eerste blijvende molaar in de bovenkaak.

Ectopic eruption of the maxillary first permanent molar is an eruption disturbance. This article discusses current literature views on diagnosis, prevalence, aetiology and treatment of this disturbance. It is a relatively uncommon disturbance and its aetiology remains unclear. A combination of extraction of the maxillary second primary molar and cervical headgear treatment seems the treatment of choice, although this treatment option is successful in only 70% of cases. More research has to be conducted to compare the effectiveness of treatment options.

Precision and accuracy of CT-based measurements of masticatory muscles in patients with hemifacial microsomia.

OBJECTIVE: The objective of this study was to quantitatively assess masticatory muscle volumes in patients with hemifacial microsomia. Until recently, this congenital malformation was only studied in terms of restoring bony and skin morphologies. Study of the masticatory muscles, however, adds a new dimension. MATERIALS AND METHODS: Contiguous 1.5 mm CT scans were made using a Philips Tomoscan 350 in six patients with hemifacial microsomia and in one patient without asymmetry. These CT scans were processed by a Cemax 1500X 3D workstation. The volume of the masseter, temporal, and medial and lateral pterygoid muscles was measured from CT scans using three-dimensional (3D) segmentation followed by 3D imaging. The precision and accuracy of measurements of masticatory muscle volumes were investigated. The precision of 3D imaging was assessed by carrying out repeated measurements by two observers. The accuracy of the volume determination technique was assessed by scanning a piece of porcine muscle tissue with a known volume. RESULTS: Intraobserver repeatability was near perfect, with the lowest alpha being 0.96 (for the medial pterygoid muscle). All interobserver correlations were high (>0.99). The accuracy of the method of measurement demonstrated differences ranging from 2.3% to 4.4%. CONCLUSION: Craniofacial soft tissue measurements obtained from CT scans in patients with hemifacial microsomia were accurate and reproducible but time consuming.

Outcome of bone grafting in relation to cleft width in unilateral cleft lip and palate patients.

OBJECTIVE: The purpose of this study was to determine the relationship between cleft width and the residual amount of bone after bone grafting in 53 unilateral cleft lip and palate patients. STUDY DESIGN: The fate of the bone graft was determined by the residual amount of bone calculated from computed tomography scans taken immediately after surgery and 1 year postoperatively. Initial cleft width was measured on the computed tomography scans taken immediately after bone grafting. RESULTS: An average cleft width of 6.4 mm (range 3.0-12.2 mm) was found. The average amount of residual bone in the cleft area after 1 year was 64% of the initial bone graft. Linear regression analysis showed that a significant correlation (r = -0.29, P =.04) was found for cleft width in relation to the percentage of residual bone after 1 year. CONCLUSION: The regression analysis indicates that a relation between cleft width and the fate of the bone graft exists. Bone grafts in wider clefts are more prone to resorption than those in more narrow ones.