Secular trend of dental development in Dutch children.

Many studies have established dental age standards for different populations; however, very few studies have investigated whether dental development is stable over time on a population level. Therefore, the aim of this study was to analyze changes in dental maturity in Dutch children born between 1961 and 2004. We used 2,655 dental panoramic radiographs of 2- to 16-year-old Dutch children from studies performed in three major cities in the Netherlands. Based on a trend in children born between 1961 and 1994, we predicted that a child of a certain age and gender born in 1963 achieved the same dental maturity on average, 1.5 years later than a child of the same age born 40 years later. After adjusting for the birth year of a child in the analysis, the regression coefficient of the city variable was reduced by 56.6% and it remained statistically significant. The observed trend from 1961 to 1994 was extrapolated to 9- to 10-year-old children born in 2002-2004, and validation with the other samples of children with the same characteristics showed that 95.9%-96.8% of the children had dental maturity within the 95% of the predicted range. Dental maturity score was significantly and positively associated with the year of birth, gender, and age in Dutch children, indicating a trend in earlier dental development during the observation period, 1961-2004. These findings highlight the necessity of taking the year of birth into account when assessing dental development within a population with a wider time span.

Patterns of tooth agenesis in patients with crouzon or apert syndrome.

PURPOSE: Dental agenesis is the most common anomaly of dental development and can be a component of a congenital syndrome. The purpose of this study was to evaluate the prevalence of agenesis and to describe patterns of tooth agenesis in patients with Crouzon or Apert syndrome compared with nonsyndromic controls. PATIENTS AND METHODS: Longitudinal records of 67 patients with Crouzon syndrome (n = 39) or Apert syndrome (n = 28) from the Erasmus Medical Centre were examined. Syndromic patients were compared with patients in a nonsyndromic control group (n = 284). RESULTS: Prevalence of tooth agenesis in patients with Crouzon syndrome (35.9%) and patients with Apert syndrome (46.4%) was significantly higher than the prevalence in control subjects (27.5%) (P < .005). In all groups third molars were the most likely to be agenetic. Tooth agenesis excluding third molars was significantly higher in syndromic patients than in control subjects (P < .001). Bilateral agenesis of mandibular second premolars occurred significantly more often in patients with Crouzon and Apert syndrome than in control subjects (P < .001). CONCLUSIONS: Tooth agenesis is more prevalent in patients with Crouzon or Apert syndrome than in control subjects. Tooth agenesis and mandibular symmetrical patterns of second premolar agenesis are more prevalent in syndromic patients.

Dental maturation in children with the syndrome of crouzon and apert.

Purpose : Developing teeth are used to assess maturity and estimate age in a number of disciplines. The purpose of this investigation was to study the dental maturation in children with Crouzon or Apert syndrome compared with nonsyndromic controls. Patients and Methods : Records of 40 children with Crouzon syndrome (18 boys and 22 girls, aged 4.0 to 17.9 years) and 28 children with Apert syndrome (10 boys and 18 girls, aged 3.9 to 15.1 years) were referred to the Department of Orthodontics, Cleft Palate Team and Craniofacial Team, Erasmus MC-Sophia. Data from syndromic children were compared with data from 451 nonsyndromic children (225 boys and 226 girls, aged 2.9 to 16.9 years). From panoramic radiographs, dental maturation was determined for patients with Crouzon and Apert syndromes and compared with data collected from control children. Logistic functions were constructed for dental maturation over time for syndromes and gender. Results : Statistically significant gender differences in dental maturation scores were found for girls with Crouzon (P < .05) and Apert syndrome (P < .05). Patients with Apert syndrome demonstrated a significantly delayed dental maturation (P < .05), while patients with Crouzon syndrome showed a nonsignificant delay. Conclusions : Dental maturation in patients with Apert syndrome was more delayed than in patients with Crouzon syndrome. The delay of tooth formation in patients with Crouzon or Apert syndrome suggests a possible common genetic association.

A longitudinal study of dental arch morphology in children with the syndrome of Crouzon or Apert.

The aim of this study was to compare changes in dental arch morphology between patients with Crouzon syndrome or Apert syndrome and controls. Children between 4 and 14 yr of age with Crouzon syndrome (n = 40) or Apert syndrome (n = 28) were compared with non-syndromic controls (n = 457) in terms of arch widths, depths, and length dimensions. Multilevel statistical modeling techniques were used to evaluate changes over time. Dental arch dimensions were found to be smaller in patients with Crouzon syndrome or Apert syndrome compared with control subjects. Maxillary intercanine width for patients with Apert syndrome were increased, whilst other arch width variables showed no change. Patients with Crouzon syndrome showed increases in maxillary intercanine width, whilst intermolar width showed no change over time. Dental arch dimensions in syndromic patients were thus found to be consistently smaller than in control subjects between 4 and 14 yr of age, implying that patients with Crouzon syndrome and Apert syndrome had a diminished growth potential.

Craniofacial Stability in Patients With Crouzon or Apert Syndrome After Le Fort III Distraction Osteogenesis.

Objective : Le Fort III osteotomy with distraction osteogenesis (DO) is used to improve the retruded midface in patients with Crouzon or Apert syndrome. This study aimed to evaluate sagittal and vertical preoperative and postoperative cephalometric changes of DO of the midface in patients with Crouzon or Apert syndrome. Design : Population-based case-control study. Patients and Methods : Records of patients with the syndrome of Crouzon (N = 6) or Apert (N = 7) were compared, before and after Le Fort III DO, with a nonsyndromic untreated control group (N = 486). Main Outcome Measures : Sagittal and vertical cephalometric maxillary landmarks and measurements were used to predict and measure midface advancement and rotation after Le Fort III DO. Cephalograms were taken before surgery (T0), 4 months after surgery at removal of the distraction device (T1), and 1 year after removal of the distraction device (T2). Analysis : Z scores were performed to compare cephalometric measures of syndromic patients with control subjects. Results : Cephalograms of 13 patients with Crouzon syndrome (N = 6) or Apert (N = 7) (age range 8.2 to 19.8 years) were evaluated. Treatment changes (T1-T2) showed statistically significant maxillary advancement, with no significant differences between the patients with the Crouzon or Apert syndrome. Conclusions : DO of the midface in patients with Crouzon or Apert syndrome seems to be stable in the sagittal direction after follow-up. Although Crouzon and Apert differ after DO, anteroposterior craniofacial dimensions were significantly improved and were closer to patterns of normal subjects.

Facial growth in patients with apert and crouzon syndromes compared to normal children.

OBJECTIVE: To evaluate vertical and sagittal facial growth in children with Apert and Crouzon syndromes and compare it to the growth patterns of a nonsyndromic control group. DESIGN: Case-control study. SETTING: Department of Orthodontics, Children's Hospital Erasmus Medical Centre, Sophia, Rotterdam, The Netherlands. PATIENTS, PARTICIPANTS: Sixty-two patients (37 patients with Crouzon syndrome and 25 patients with Apert syndrome) born between 1971 and 2001 (age range 3.9 to 32 years) and 482 nonsyndromic children as a control group. INTERVENTIONS: Lateral cephalograms performed prior to any midfacial surgery of 62 patients and 482 nonsyndromic children were traced and horizontal and vertical measurements were digitized. MAIN OUTCOME MEASURES: Cephalometric measurements of SNA, SNB, ANB, NSMe, and SN/palatal plane angles and lower facial height ratio. RESULTS: Horizontal measurements for the syndromic groups showed no change in SNA angle during growth. SNA angles were lower in patients with Apert syndrome compared to patients with Crouzon syndrome. The syndromic groups showed smaller values for ANB angles compared to the nonsyndromic group. Vertical measurements showed increased lower facial height ratios for the syndromic groups compared to control subjects. There was an increasing counterclockwise rotation of the palatal plane in relation to the anterior cranial base in syndromic patients. NSMe angles among the three groups were not significantly different. CONCLUSIONS: Based on the growth differences identified, the sagittal and vertical jaw relationships differ in patients with Crouzon syndrome, patients with Apert syndrome, and control subjects. Syndromic patients show aggravation of midfacial underdevelopment and anterior rotation of the mandible.

Severe hypodontia: identifying patterns of human tooth agenesis.

Tooth agenesis is the most common dental anomaly. The aim of this retrospective study was to identify common patterns of tooth agenesis in a sample of 92 patients (55 females and 37 males; mean age 27.7 years) with non-syndromic severe hypodontia. The Tooth Agenesis Code (TAC) procedure was used for that purpose. The patients in this study were missing between 6 and 22 permanent teeth (mean 11.6; median 10.0; SD 4.35). In the maxilla, 47.9 (left side) and 50.0 (right side) per cent can be described using only five different patterns. The most common patterns involved agenesis of the maxillary lateral incisor and both premolars. In the mandible, 35.8 (lower left) or 43.5 (lower right) per cent can be described by five patterns, the most common of which was agenesis of all mandibular premolars. When comparing patients with and without symmetric agenesis patterns (symmetry in the upper or lower arch versus no symmetry), a Student's t-test revealed no difference in the total number of missing teeth. Common patterns of tooth agenesis were successfully identified in patients with non-syndromic severe hypodontia. The present findings may be used to develop interdisciplinary treatment protocols for the most common patterns to increase the quality of interdisciplinary treatment for patients with severe hypodontia.

Long-term follow-up of craniofacial alterations in juvenile idiopathic arthritis.

OBJECTIVE: To investigate changes in the craniofacial skeleton in relation to the changes in condylar alterations that occur during long-term follow-up in patients with juvenile idiopathic arthritis. MATERIALS AND METHODS: Temporomandibular joint (TMJ) involvement is defined as a condylar alteration that is observed on the orthopantomogram. Lateral cephalograms were used to determine linear and angular measurements. RESULTS: Seventy of 97 patients from the initial study cohort were included, with a mean follow-up of 68 months. The overall prevalence of condylar alterations and posterior rotation of the mandible decreased; however, the prevalence of retrognathia remained the same. Patients showed improvement in the degree of retrognathia and posterior rotation (40% ANB, 51% OP-SN, and 44% GO-GN-SN). Improvement in the degree of retrognathia was seen more often in patients with improved condylar alterations than in patients with persistent alterations and in those without alterations (50%, 33%, and 28%, respectively). The degree of posterior rotation improved almost equally in patients without TMJ involvement and in patients with improved condylar alterations (57% and 50% by OP-SN, and 67% and 38% GO-GN-SN, respectively) and did not improve in patients with stable persistent alterations. CONCLUSION: Both condylar and craniofacial alterations can improve in patients with juvenile idiopathic arthritis.

Infant orthopedics and facial growth in complete unilateral cleft lip and palate until six years of age (Dutchcleft).

OBJECTIVE: To evaluate longitudinally the effect of infant orthopedics (IO) on dentofacial cephalometric variables in unilateral cleft lip and palate (UCLP) patients from 4 to 6 years of age. DESIGN: Prospective two-arm randomized controlled clinical trial in three cleft palate centers in The Netherlands (Dutchcleft trial). PATIENTS: Fifty-four children with complete UCLP. INTERVENTIONS: Patients were divided randomly into two groups. Half of the patients (IO+) had IO until surgical closure of the soft palate at the age of +/-52 weeks; the other half (IO-) received no intervention. MEAN OUTCOME MEASURES: Cephalometric values representing soft tissue, hard tissue, and dental structures, measured on lateral headfilms made at 4 and 6 years of age. RESULTS: In the IO+ group, 21 patients were analyzed; in the IO- group, 20 patients were analyzed at age 4 and 22 at age 6. No differences were found between IO+ and IO-, except for two measurements: The interincisal angle was larger and the mentolabial angle was smaller in the IO+ group. CONCLUSIONS: For infants with UCLP whose surgical management included soft palate repair at 12 months and delayed hard palate closure, cephalometric outcomes at ages 4 and 6 provide no indication for the type of IO used in this study.

Oral health-related quality of life and dental esthetics in Amsterdam schoolchildren.

PURPOSE: The purpose of this study was to examine the oral health-related quality of life (OHRQoL) of schoolchildren in Amsterdam, The Netherlands, and to assess the relationship between OHRQoL and self-reported dental esthetics. METHODS: The Child Oral Health Impact Profile (COHIP) was completed by 510 seventh and eighth graders of public primary schools. Subjects also assessed their own dentition with the Esthetic Component of the Index of Orthodontic Treatment Need (AC-IOTN). Gender differences on COHIP subscales and the AC-IOTN were examined using Mann-Whitney U tests. Correlations between the COHIP subscales and the AC-IOTN were assessed with Spearman's rank correlation coefficient. RESULTS: Boys scored significantly lower on the subscales "oral symptoms" and "emotional well-being" than girls. Correlations between OHRQoL and the AC-IOTN were low but significant for boys for the domains "oral symptoms" (0.137) and "emotional well-being" (0.186) and for girls for the domains "functional well-being" (0.148), "emotional well-being" (0.195), and "peer interaction" (0.215). CONCLUSIONS: Dutch schoolchildren in Amsterdam generally reported good oral health-related quality of life. Boys seemed to experience a slightly lower impact of oral symptoms and better emotional well-being than girls. Children's self-perceived dental esthetics did not seem to constitute a relevant variable to explain their level of OHRQoL.

Age-dependant cephalometric standards as determined by multilevel modeling.

INTRODUCTION: The purpose of this study was to evaluate the feasibility of constructing age-dependant cephalometric standards for white subjects by using 3 data sets. METHODS: The data sets were the samples from the Fels Longitudinal Study (United States), the Michigan Growth Study (United States), and the Nijmegen Growth Study (The Netherlands). The 3 mixed-longitudinal samples provided data for 218 girls and 231 boys between 9 and 14 years of age and were compared based on 4 cephalometric angles: SNA, SNB, ANB, and SN/GoMe. Curve-fitting and statistical comparisons were performed with multilevel modeling procedures. RESULTS: All 4 angles showed linear changes over time. SNA and SNB increased, whereas ANB and SN/GoMe decreased. Based on paired-sample comparisons, the samples displayed statistically significant (P <0.05) differences for 50% of the growth velocities and 8% to 17% of the intercepts (size of the angle at 11 years). The SNA and SNB angles showed small and inconsistent differences across the samples. The ANB angle for the Fels boys decreased less than in the other 2 samples. The Nijmegen and Fels girls had the greatest and the least decreases, respectively, in the SN/GoMe angle. Most sample differences decreased over time. CONCLUSIONS: Based on the growth differences identified, we concluded that sagittal and vertical jaw relationships have different patterns of growth in different samples of white subjects; indiscriminate pooling of data, to create age-dependant cephalometric standards for white subjects is not recommended.

Dutch primary schoolchildren's attitudes toward their dental appearance.

PURPOSE: This study's purpose was to examine children's attitudes toward dental appearance and compare these with attitudes toward general health, body shape, grades in school, friends, money, and sports. The study also explored whether subjects reporting that they have attractive teeth believed themselves to have higher grades in school, more friends, a slim body shape, and better health than subjects reporting that they have unattractive teeth. METHODS: A sample of 216 9- to 13-year-old Dutch children participated. The methods of paired comparisons and direct ranking were used to investigate children's judgments about the importance of dental appearance. The subjects were also asked to indicate how strongly they believed that they had high grades in school, a lot of friends, money, success in sports, attractive teeth, a slim body shape, and good health. RESULTS: High grades in school, a slim body shape, good health, a lot of friends, and more money were preferred to attractive teeth. Children reporting that they have attractive teeth believed themselves to have higher grades in school, a slimmer body shape, more friends, more money, and better health than children reporting that they have unattractive teeth. CONCLUSIONS: Although attractive teeth are highly valued in general, children give priority to other issues in their lives.

Craniofacial morphology of Dutch patients with bilateral cleft lip and palate and noncleft controls at the age of 15 years.

OBJECTIVE: Comparison of craniofacial morphology in bilateral cleft lip and palate patients to that of a noncleft control group at the age of 15 years. DESIGN: A cross-sectional study of cephalometric data. SUBJECTS AND METHODS: Cephalometric records of 41 consecutive patients (32 boys and 9 girls) with nonsyndromic complete bilateral cleft lip and palate born between 1973 and 1987. The patients were treated by the cleft teams of the Erasmus Medical Centre in Rotterdam and the VU University Amsterdam. The control group of normal Dutch subjects was followed in the Nijmegen Growth Study. From this population, mean cephalometric data were used. Differences in cephalometric measurements and other variables were calculated between the bilateral cleft lip and palate group and the control group. RESULTS: Independent-sample t tests indicated that there was a statistically significant difference between the mean of the cephalometric values of the bilateral cleft lip and palate patients and the control group with respect to all cephalometric variables. Pearson correlation coefficients calculated between angle ANB and the number of operators, number of surgical procedures before 15 years of age, and the year of birth were not significant. CONCLUSIONS: Bilateral cleft lip and palate patients treated in the Amsterdam and Rotterdam cleft centers differed significantly from the control group in all measurements. A Class III development due to a less forward positioned maxilla was observed. The vertical measurements indicated a more divergent growth pattern in bilateral cleft lip and palate patients (Ans-Me/N-Me, GoGn-SN, and SN-FFH).

The influence of dynamic fatigue loading on the separate components of the bracket-cement-enamel system.

PURPOSE: To evaluate the influence of cyclic loading and type of adhesive on the shear bond strength of the bracket-cement-enamel bond. METHODS: The materials studied were: Transbond XT (a Bis-GMA resin composite cement), Fuji Ortho LC (a resin-modified glass-ionomer cement), and Fuji IX Fast (a conventional glass-ionomer cement). The shear bond strength (SBS) and the shear bond fatigue limits (SBFL) were determined after 72-hour storage in 37 degrees C water for the cement itself, the button-cement interface, the cement-enamel interface, and the bracket-cement-enamel system. The SBFL was determined with the aid of the "staircase method" at 10,000 cycles. The results were analyzed using ANOVA and Tukey HSD post hoc test (P < 0.05). RESULTS: ANOVA showed significant differences between the SBS of the materials. Fatigue was observed in all substrate combinations, with the exception for the Fuji IX Fast cement-enamel and the Fuji Ortho LC bracket-cement-enamel combinations.

The influence of different bracket base surfaces on tensile and shear bond strength.

Fracture of the bracket-cement-enamel system usually takes place between the bracket and the cement. Especially for glass ionomer-based materials, it is helpful if this part of the system can be improved. The aim of this in vitro study was to investigate the influence of different bracket base pre-treatments in relation to three different cements, Transbond XT, a resin composite, Fuji Ortho LC, a resin-modified glass ionomer cement (GIC), and Fuji IX Fast, a conventional glass ionomer cement, on shear as well as on the tensile bond strength. Upper incisor brackets with three types of base treatment, sandblasted, silicoated, and tin-plated, were bonded to bovine enamel. Untreated brackets were used as the controls. Ten specimens were tested for each group. The brackets were stored for 24 hours after bonding and tested in shear as well as in tensile mode. After fracture the remaining adhesive was scored using the adhesive remnant index (ARI). Analysis of variance was used to detect statistical differences between the bond strengths at a level of P < 0.05. Although some of the bracket pre-treatments had a statistically significant effect on bond strength, no clear improvement was measured. The ARI scores of the test groups did not show a change when compared with the control groups. The investigated base pre-treatments did not have such a beneficial influence on bond strength that improved clinical results can be expected. Improvement of the bond between bracket and cement might be found in other variables of the bracket-cement-enamel system such as the elasticity of the materials.

Effect of infant orthopedics on facial appearance of toddlers with complete unilateral cleft lip and palate (Dutchcleft).

OBJECTIVE: To evaluate the effect of infant orthopedics (IO) on facial appearance of 54 patients with unilateral cleft lip and palate (UCLP), aged 4 and 6 years. DESIGN: Prospective two-arm randomized controlled clinical trial in three Cleft Palate Centers in the Netherlands (Dutchcleft-trial). INTERVENTIONS: Patients were divided randomly into two groups. Half of the patients (IO+) had a plate until surgical closure of the soft palate at the age of +/- 52 weeks; the other half (IO-) received no intervention. MAIN OUTCOME MEASURES: Facial appearance at 4 and 6 years of age assessed on full face photographs and photographs showing only nose and mouth. Ratings were performed on a VAS-scale by professionals and laymen. RESULTS: At 4 years of age the full face pictures of IO+ children were scored to be more attractive than those of IO- children. However, this difference had disappeared at 6 years of age. At the age of 6, only professionals saw a significant difference on nasolabial photographs between IO+ and IO-. Regression analysis showed a minor effect of occlusion, lip revision, or type of nose reconstruction on the esthetic results. CONCLUSIONS: IO had a positive effect on full facial appearance of UCLP children at the age of 4 years, but at the age of 6, only professionals saw a positive effect of IO on the nasolabial photographs. This is irrelevant for UCLP patients since they deal with laymen in their daily life.

Presurgical orthopedics and satisfaction in motherhood: a randomized clinical trial (Dutchcleft).

OBJECTIVE: To study the effect of infant orthopedics on satisfaction in motherhood. DESIGN: Prospective two-arm randomized controlled trial in parallel with three participating academic cleft palate centers. Treatment allocation was concealed and was performed by means of a computerized balanced allocation method. SETTING: Cleft palate centers of Amsterdam, Nijmegen, and Rotterdam, the Netherlands. PATIENTS: Two groups of infants with complete unilateral cleft lip and palate and no other malformations. INTERVENTIONS: Group IO+ (n = 27) wore passive maxillary plates during the first year of life, group IO- (n = 27) did not. MAIN OUTCOME MEASURE(S): Mean satisfaction scores were obtained from completed questionnaires at 6, 24, and 58 weeks of age. A 4-point scale was used (1 = very satisfactory to 4 = very unsatisfactory). RESULTS: The range of the mean scores for the individual items on the questionnaires for both groups ranged between 1.1 and 2.4. No differences were found between groups. Mothers appear to be satisfied in motherhood, least satisfied with the available time for themselves, and very satisfied with hugging and walking their babies. No differences were found between groups. CONCLUSIONS: Results from the present study show that infant orthopedics, with a passive plate during the first year of life, in children with a unilateral cleft lip and palate has no influence on the mothers' satisfaction in motherhood.

Long-term followup of temporomandibular joint involvement in juvenile idiopathic arthritis.

OBJECTIVE: Temporomandibular joint (TMJ) involvement is a frequent feature in cross-sectional prevalence studies among patients with juvenile idiopathic arthritis (JIA). In this followup study, patients were reviewed after 5 years to study the course of TMJ involvement in relation to disease characteristics. METHODS: Children with JIA from a previous study on TMJ involvement were included. A rheumatologic evaluation including the 6 parameters of the JIA core set and an orthodontic evaluation including an orthopantomogram (OPT) were performed. OPTs were scored according to Rohlin's grading system (grades 0-5). RESULTS: The overall prevalence of patients with condylar alterations decreased from 49% to 40%. Improvement of the alterations was seen in 69% of the initially affected condyles, and consequently improvement was seen in 83% of the initially affected patients. Normalization of the alterations was seen in 67% of the improved condyles, and consequently in 44% of the patients. This proves that the condyle has a regenerative capacity. Improvement was related to low disease activity and a less extensive therapeutic regimen. CONCLUSION: In patients with JIA, condylar alterations can improve and even regenerate. Condylar improvement is associated with a low disease activity.

Confirmative factor analysis of the dimensions of the Child Oral Health Impact Profile (Dutch version).

The aim of this study was to examine the subscales of the Child Oral Health Impact Profile (COHIP). The Dutch version of the COHIP consists of the subscales 'Oral Symptoms', 'Functional Well-being', 'Emotional Well-being', 'School', and 'Peer Interaction'. The questionnaire was administered to a sample of 510 children in Amsterdam. Missing data were replaced with the personal mean. Subsequently, questionnaire reliability was investigated by means of corrected item-total correlations and Cronbach's alpha if-item-deleted. Based on these results, six items were excluded from further analysis. Then, the questionnaire and its subscales were examined using confirmative factor analyses. One-factor models were fitted on each subscale and a five-factor model was applied to the entire questionnaire. In several cases, model fit was below an acceptable level. In conclusion, the structure of five subscales does not seem to be entirely supported in this study population.

Effect of long-term repeated deflections on fatigue of preloaded superelastic nickel-titanium archwires.

INTRODUCTION: The aim of this in-vitro study was to investigate the changes in force delivery of superelastic nickel-titanium archwires used in combination with a self-ligating bracket system after dynamic fatigue-loading in a 3-bracket model under controlled temperature. METHODS: Samples of 2 superelastic nickel-titanium (active austenitic) wires, a conventional nickel-titanium wire, and a stainless steel wire, all 0.014-in round, were divided into 2 groups: static deflection and dynamic deflection. The static specimens were under a constant deflection of 3.0 mm. The dynamic specimens had the same constant deflection of 3.0 mm but were subjected to additional repeated deflections of 0.5 mm, applied by a fatigue tester. The test situation simulates a patient's archwire under deflection and subjected to occlusal contact during 1, 100, 10,000, and 100,000 cycles. Fatigue changes were assessed with a 3-point bending test. RESULTS: Type of wire, loading or unloading, and number of cycles as within-subject factors were statistically significantly different. No statistically significant difference between the test condition, static vs dynamic, was found. The repeated deflections of 0.5 mm were not enough to induce an extra effect of fatigue. CONCLUSIONS: Occlusal forces transferred to a considerably deflected archwire, such as in the large malalignments in the early stages of orthodontic treatment, will have no fatigue effect on the unloading force of that archwire.