Functionality testing of an innovative biomechanically optimized and surface-modified orthodontic mini-screw-a comparative study.

PURPOSE: The failure rate of orthodontic mini-screws depends strongly on primary stability and, thus, on insertion torque. Further improvement regarding the failure rate might be achieved by modifying the surface coating. Therefore, the aim of the study was to investigate the stability of a newly designed and surface-modified orthodontic mini-screw in beagle dogs. METHODS: Newly designed mini-screws coated either with DOTIZE® or DOTIZE®-copper (DOT GmbH, Rostock, Germany; each: n = 24) were inserted in the mandibles of eight beagle dogs for a duration of 8 months. Insertion and removal torque were measured. These data were compared to values generated by using the artificial bone material Sawbones® (Sawbones Europe AB, Malmö, Sweden). Experiments with and without torque limitation (each: n = 5) were run. The bone-to-implant contact rate and the amount of bone between the threads were examined. Statistical significance was set at P < 0.05. RESULTS: The success rates of the in vivo study reached high levels with 95.3% for the DOTIZE-coated and 90.5% for the DOTIZE-copper-coated screws, whereas the insertion and removal torque did not differ between the coatings. During insertion, a torque limitation of 20 Ncm was necessary to ensure that the recommended limit was not exceeded. The insertion in Sawbones without torque limitation revealed a significantly higher torque compared to torque-limited insertion (18.2 ± 1.3 Ncm, 23.6 ± 1.3 Ncm). Bending occurred (n = 5) in the thread-free part of the mini-screw. CONCLUSIONS: Surface coating might be able to improve the performance of orthodontic mini-screws. The study showed high success rates and stable mini-screws until the end of observation. Further investigations are necessary.

Orthodontic treatment and biological limits: a retrospective clinical trial.

BACKGROUND: The fundamental part of every successful orthodontic treatment is the detailed treatment planning including a precise determination of the virtual treatment objective (VTO) while considering the biological and anatomical limits. The aim of this study is to investigate and to compare the feasibility of the established reference values before and after orthodontic treatment and to determine the usefulness of this parameters as guidance for the sagittal anterior, sagittal posterior and transverse biological boundaries. MATERIALS AND METHODS: Thirty-two patients aged 9 to 18 years (12 male and 20 female) with all permanent teeth present were randomly selected for orthodontic treatment with fixed multibracket appliance regardless of the potential malocclusion. The parameters 6-PTV, 1-NB [mm] and the WALA ridge were set for the identification of the transverse, sagittal anterior and sagittal posterior tooth position. The measurements were carried out at the beginning (T0) and at the end (T1) of the orthodontic treatment. They were set in relation with their individual threshold values (G). After the results of the measurements were conducted using the software OnyxCeph3TM (version 3.2.185 (505), Image Instruments GmbH, Chemnitz, DE), they were statistically calculated in the software RStudio (2022.12.0 Build 353 © 2009-2022 Posit Software PBC). RESULTS: Among the 32 patients, the mean pre- and post-treatment changes measured through the three parameters in relation to the individual reference values were statistically significant (p < 0.01). The mean values for 6-PTV, 1-NB and the WALA ridge amounted 15.37 mm, 2.56 mm and 4.23 mm at the beginning of the treatment, while after the treatment the measured values amounted 20.31 mm, 2.4 mm and 5.55 mm. These measurements combined with the statistical analysis of the changes of WALA ridge (T0, T1) confirmed that the teeth have been successfully uprighted and aligned. Furthermore, the maxillary first molars have been moved slightly mesially, as proven by the changes in 6-PTV, without certainty as to whether bodily movement or mesial tipping took place. Additionally, the lower incisors have been protruded, slightly exceeding the individual threshold values. CONCLUSION: The parameters investigated provide a suitable assessment tool for recording the limits of the sagittal posterior, the sagittal anterior and the transverse dimension.

Influence of Test Specimen Geometry and Water Soaking on the In Vitro Cytotoxicity of Orthocryl®, Orthocryl® LC, Loctite® EA 9483 and Polypropylene.

Depending on their composition, plastics have a cytotoxic potential that needs to be evaluated before they are used in dentistry, e.g., as orthodontic removable appliances. Relevant guidelines set out requirements that a potential new resin in the medical field must meet, with a wide scope for experimental design. In the present study, test specimens of different geometries consisting of varying polymers (Orthocryl®, Orthocryl® LC, Loctite® EA 9483, Polypropylene) were soaked for different periods of time, then transferred to cell culture medium for 24 h, which was subsequently used for 24-h cultivation of A549 cells, followed by cytotoxicity assays (WST-1, Annexin V-FITC-propidium iodide (PI) flow cytometry). In this context, a reduction in the cytotoxic effect of the eluates of test specimens prepared from Orthocryl® LC and Loctite® EA 9483 was particularly evident in the Annexin V-FITC-PI assay when the soaking time was extended to 48 h and 168 h, respectively. Consistent with this, a reduced release of potentially toxic monomers into the cell culture medium, as measured by gas chromatography-mass spectrometry, was observed when the prior soaking time of test specimens of all geometries was extended. Remarkably, a significant increase in cytotoxic effect was observed in the WST-1 assay, which was accompanied by a higher release of monomers when the thickness of the test sample was increased from 0.5 to 1.0 mm, although an elution volume adapted to the surface area was used. However, further increasing the thickness to 3.0 mm did not lead to an increase in the observed cytotoxicity or monomer release. Test specimens made of polypropylene showed no toxicity under all test specimen sizes and soaking time conditions. Overall, it is recommended to perform toxicity studies of test specimens using different geometries and soaking times. Thereby, the influence of the different specimen thicknesses should also be considered. Finally, an extension of the test protocols proposed in ISO 10993-5:2009 should be considered, e.g., by flow cytometry or monomer analysis as well as fixed soaking times.

Longitudinal changes in the dental arches and soft tissue profile of untreated subjects with normal occlusion.

AIM: The aim of this study was to analyze dental and soft tissue profile development in children with normal occlusions to establish age- and gender-specific reference intervals for German children during their active growth period. SUBJECTS AND METHODS: The study group consisted of a sample of 31 untreated Caucasian subjects with normal occlusions. Dental casts were analyzed at four different stages of dentitional development. Extraoral profile photographs were available for 19 subjects at stages T2-T4. In these subjects 11 angular measurements and 14 indices were analyzed. Statistical comparisons of gender-specific differences were performed by Mann-Whitney U tests (p ≤ 0.05). RESULTS: Upper and lower posterior and total arch perimeters were recorded to be significantly larger in male subjects until the late mixed dentition. Subsequently, there was a tendency toward larger dimensions in males for those parameters. Upper and lower intercanine, interpremolar and intermolar widths were significantly larger in males throughout the entire observation period. There were no statistically significant gender differences with regard to most angular measurements in the dental arches, including molar rotation, palatal volume, overbite, overjet and molar relationship at later dental stages. CONCLUSION: In untreated subjects with normal occlusion, dental arch and soft tissue parameters can be considered age-dependent. For some dental parameters, gender-specific differences were found that should be taken into consideration during diagnosis and treatment planning of growing children. The obtained longitudinal data of untreated children provide useful information for orthodontic diagnosis, treatment planning and future research projects.

Skeletal effects in Angle Class II/1 patients treated with the functional regulator type II : Cephalometric and tensor analysis.

OBJECTIVES: The purpose of this work was to employ both cephalometric and tensor analysis in characterizing the skeletal changes experienced by patients with Angle Class II/1 malocclusion during functional orthodontic treatment with the functional regulator type II. METHODS: A total of 23 patients with Class II/1 malocclusion based on lateral cephalograms obtained before and after treatment with the functional regulator type II were analyzed. Another 23 patients with Angle Class II/1 malocclusion who had not undergone treatment were included as controls. RESULTS: Our cephalometric data attest to significant therapeutic effects of the functional regulator type II on the skeletal mandibular system, including significant advancement of the mandible, increases in effective mandibular length with enhancement of the chin profile, and reduction of growth-related bite deepening. No treatment-related effects were observed at the cranial-base and midface levels. In addition, tensor analysis revealed significant stimulation of mandibular growth in sagittal directions, without indications of growth effects on the maxilla. Its growth-pattern findings differed from those of cephalometric analysis by indicating that the appliance did promote horizontal development, which supports the functional orthodontic treatment effect in Angle Class II/1 cases. CONCLUSIONS: Tensor analysis yielded additional insights into sagittal and vertical growth changes not identifiable by strictly cephalometric means. The functional regulator type II was an effective treatment modality for Angle Class II/1 malocclusion and influenced the skeletal development of these patients in favorable ways.

Long-term outcomes of Class III treatment with mandibular cervical headgear followed by fixed appliances.

OBJECTIVE: To evaluate the stability of the outcomes of mandibular cervical headgear (MCH) and fixed appliance-treated Class III patients at a long-term posttreatment (5 years) observation, compared with well-matched untreated Class III controls, following a previous report on the short-term outcomes of this protocol. MATERIALS AND METHODS: The treated group consisted of 20 patients with dentoskeletal Class III malocclusions treated with a two-phase protocol consisting of MCH and fixed appliances, while the control group comprised 18 untreated subjects with similar dentoskeletal Class III malocclusion. Lateral cephalograms of both patients and controls were analyzed at two time points: posttreatment (PT), after two-phase treatment; and long term (LT). All patients were at a postpubertal stage of skeletal maturity at PT, and they showed CS6 at LT, thus revealing completion of pubertal craniofacial growth. RESULTS: In the long term, the treatment group showed significantly smaller values for mandibular length (Co-Gn), SNB angle, maxillomandibular differential, and molar relation. When compared with the controls, the treated patients exhibited also greater values for ANB angle, Wits appraisal, and overjet at LT. No significant difference between the two groups was found for the changes occurring from PT to LT. CONCLUSIONS: Favorable dentoskeletal outcomes induced by MCH and fixed appliances remained stable in the long term; untreated Class III malocclusion did not show any tendency toward self-improvement during the postpubertal interval.

Comparison of 2 comprehensive Class II treatment protocols including the bonded Herbst and headgear appliances: a double-blind study of consecutively treated patients at puberty.

INTRODUCTION: The aim of this clinical trial was to compare the effects of 2 protocols for single-phase comprehensive treatment of Class II Division 1 malocclusion (bonded Herbst followed by fixed appliances [BH + FA] vs headgear followed by fixed appliances and Class II elastics [HG + FA]) at the pubertal growth spurt. METHODS: Fifty-six Class II patients were enrolled in the trial and allocated by personal choice to 2 practices, where they underwent 1 of 2 treatment protocols (28 patients were treated consecutively with BH + FA, and 28 patients were treated consecutively with HG + FA). All patients started treatment at puberty (cervical stage [CS] 3 or CS 4) and completed treatment after puberty (CS 5 or CS 6). Lateral cephalograms were taken before therapy and 6 months after the end of comprehensive therapy, with an average interval of 28 months. Longitudinal observations of a matched group of 28 subjects with untreated Class II malocclusions were compared with the 2 treated groups. Analysis of variance (ANOVA) with post-hoc tests was used for statistical comparisons. Discriminant analysis was applied to identify preferential candidates for the BH + FA protocol on the basis of profile changes (advancement of the soft tissues of the chin). RESULTS: The success rate (full occlusal correction of the malocclusion after treatment) was 92.8% in both treatment groups. The BH + FA group showed a significant increase in mandibular protrusion. The increase in effective mandibular length (Co-Gn) was significantly greater in both treatment groups when compared with natural growth changes in the Class II controls. Significantly greater improvement in sagittal maxillomandibular relationships was found in the BH + FA group. Retrusion of maxillary incisors and mesial movement of mandibular molars were significant in the HG + FA group. The BH + FA group showed significantly greater forward movements of soft-tissue B-point and pogonion compared with both the HG + FA and the control groups. Two pretreatment variables were significant (F = 4.48; P <0.01) in predicting the posttreatment amount of mandibular soft-tissue improvement in the BH + FA group: Co-Go-Me and pogonion to nasion perpendicular. CONCLUSIONS: Class II treatment with either protocol during the pubertal growth spurt induces significant favorable dentoskeletal and occlusal changes. Functional jaw orthopedics had a greater favorable impact on the advancement of the chin. The clinical indications for the preferential use of the Herbst appliance at puberty are a small mandibular angle and mandibular retrusion before treatment. When treated with the BH + FA protocol, these Class II patients have the greatest probability of achieving significant improvement in the profile by advancement of the soft tissues of the chin.

Dentofacial growth changes in subjects with untreated Class II malocclusion from late puberty through young adulthood.

INTRODUCTION: The purpose of this longitudinal study was to compare dentofacial growth changes in untreated subjects with Class II Division 1 malocclusion with those in subjects with normal (Class I) occlusion from late puberty through young adulthood. METHODS: The Class II Division 1 sample consisted of 23 subjects (10 male, 13 female). The Class I sample included 30 subjects (13 male, 17 female). The lateral cephalograms of the subjects in both groups were analyzed at 2 consecutive stages of development: T1, postpubertal observation (cervical vertebral maturation stage 6), and T2, young adulthood stage. The average time between T1 and T2 was 3.5 years. The statistical comparisons of the growth changes in the 2 groups were performed with Mann-Whitney U tests. RESULTS: From late puberty through young adulthood, dentofacial growth in subjects with untreated Class II malocclusion does not show significant differences when compared with that observed in untreated subjects with normal occlusion. CONCLUSIONS: These findings show that Class II dentoskeletal disharmony does not exhibit significant growth change from late puberty through young adulthood.

Longitudinal growth changes in untreated subjects with Class II Division 1 malocclusion.

INTRODUCTION: The purpose of this longitudinal study was to compare the craniofacial growth changes in untreated subjects with Class II Division 1 malocclusion with those in subjects with normal (Class I) occlusion from the prepubertal through the postpubertal stages of development, as defined by a biological indicator of individual skeletal maturity (cervical vertebral maturation method). METHODS: The Class II Division 1 sample consisted of 17 subjects (11 boys, 6 girls). The Class I sample also consisted of 17 subjects (13 boys, 4 girls). The lateral cephalograms of the subjects in both groups were analyzed at 6 consecutive stages of development, from CS1 through CS6. The statistical comparisons of the growth changes in the study groups were performed with Mann-Whitney U tests. RESULTS: Craniofacial growth in subjects with untreated Class II malocclusion is essentially similar to that in untreated subjects with normal occlusion at all developmental intervals, with the exception of significantly smaller increases in mandibular length (P <0.001) at the growth spurt (interval CS3-CS4) and during the overall observation period (intervals CS1-CS6). CONCLUSIONS: Class II dentoskeletal disharmony does not tend to self-correct with growth in association with worsening of the deficiency in total mandibular length and mandibular ramus height.

Interrelation between occlusal findings and orofacial myofunctional status in primary and mixed dentition: Part III: Interrelation between malocclusions and orofacial dysfunctions.

AIM: It was the purpose of this study to analyze the relationship between selected types of malocclusion and specific types of static and dynamic orofacial dysfunction and to compare the results with subjects presenting regular occlusion. We aimed to identify which orthodontic and functional symptoms in early dentition would lead to malocclusion later on. SUBJECTS AND METHODS: Occlusal relations and myofunctional status were evaluated in 3,041 children. We diagnosed dynamic and static myofunctional disorders as well as oral habits by means of functional examinations. RESULTS: No orofacial dysfunctions were found in 11.2% of the children with primary dentition and in 10.2% of the children with early mixed dentition. We observed no correlation between the existence of distoclusion and functional disorders. Lateral crossbite in mixed dentition, as well as increased overjet and frontal open bite in primary and early mixed dentitions appeared significantly more frequently in children with orofacial dysfunctions. Individuals with frontal open bite, lateral crossbite, reduced and increased overjet presented static dysfunctions significantly more frequently than those in dentitions with normal occlusion. Dynamic dysfunctions were significantly more prevalent in subjects with frontal open bite and lateral crossbite than in those with normal occlusion. CONCLUSIONS: Our results enable us to prognosticate which children risk future orthodontic problems. Any child presenting one of the four occlusal disorders plus one static or two dynamic dysfunctions is a child more likely to develop orthodontic problems later on. Orthodontic prevention and early treatment must include functional rehabilitation so as to eliminate or at least diminish those factors causing undesirable developments.

Thin-plate spline analysis of craniofacial growth in Class I and Class II subjects.

OBJECTIVE: To compare the craniofacial growth characteristics of untreated subjects with Class II division 1 malocclusion with those of subjects with normal (Class I) occlusion from the prepubertal through the postpubertal stages of development. MATERIALS AND METHODS: The Class II division 1 sample consisted of 17 subjects (11 boys and six girls). The Class I sample also consisted of 17 subjects (13 boys and four girls). Three craniofacial regions (cranial base, maxilla, and mandible) were analyzed on the lateral cephalograms of the subjects in both groups by means of thin-plate spline analysis at T1 (prepubertal) and T2 (postpubertal). Both cross-sectional and longitudinal comparisons were performed on both size and shape differences between the two groups. RESULTS: The results showed an increased cranial base angulation as a morphological feature of Class II malocclusion at the prepubertal developmental phase. Maxillary changes in either shape or size were not significant. Subjects with Class II malocclusion exhibited a significant deficiency in the size of the mandible at the completion of active craniofacial growth as compared with Class I subjects. CONCLUSION: A significant deficiency in the size of the mandible became apparent in Class II subjects during the circumpubertal period and it was still present at the completion of active craniofacial growth.

Relationship between occlusal findings and orofacial myofunctional status in primary and mixed dentition. Part II: Prevalence of orofacial dysfunctions.

AIM: The aim of this study was to provide basic data on the prevalence of orofacial dysfunctions in primary and early mixed dentition and to examine occlusal relationships in their functional context, and to analyze the need for and potential of orthodontic prevention and early treatment. SUBJECTS AND METHODS: We assessed the occlusal relationships and myofunctional status of 3,041 children. The presence of dynamic and static myofunctional disorders and any oral habits were documented during functional analysis. RESULTS: The frequency of myofunctional disorders was statistically significantly higher in children with increased maxillary overjet, frontal open bite, lateral crossbite and mandibular prognathism, and there was a statistically significant increase in the prevalence of orofacial dysfunctions and oral habits from primary to mixed dentitions. CONCLUSIONS: Habitual open mouth posture (expressing hypotonia in the perioral muscles) and a visceral swallowing pattern become established during the primary dentition and are increasingly carried over into the mixed dentition period. Both criteria, along with assessment of occlusal relationships, are appropriate parameters with which to identify "children at risk for orthodontic treatment".

[Relationship between occlusal findings and orofacial myofunctional status in primary and mixed dentition. Part I: Prevalence of malocclusions].

AIM: The aim of this study is to provide basic data on the prevalence of malocclusions and orofacial dysfunctions in the primary and early mixed dentition, to examine occlusal relationships in their functional context, and to analyze the need for and potential of orthodontic prevention. SUBJECTS AND METHODS: Occlusal relationships and myofunctional status were evaluated in 766 children in the primary dentition and in 2,275 children in the early mixed dentition. Orthodontic findings in single jaws and intermaxillary occlusal relationships were clinically analyzed in all three dimensions. RESULTS: Normal occlusal relationships were found in 25.3% of children in the primary dentition. Frequency of children with normal dentitions fell significantly in the mixed dentition (7.3%). Prevalence of bilateral distoclusion increased significantly from the primary to the mixed dentition. Increased maxillary overjet was diagnosed in 49.3% and 59.0% of the children in the primary and mixed dentition, respectively. Prevalence of lateral crossbites increased significantly from primary to mixed dentition (7.2% vs. 12.0%). Deep bites and edge-to-edge bites were found significantly more often in the early mixed dentition. CONCLUSIONS: The significant increase in the prevalence of malocclusions between the primary and mixed dentition--distoclusion and lateral crossbite, and the impairment of vertical occlusal relationships in the mixed dentition in particular--reveal the need for orthodontic prevention. They highlight the absence of applied interceptive and early treatment measures in orthodontics. The indication system in current use for early orthodontic treatment here in Germany fails to fulfill the requirements for prevention-oriented dental care.

Presurgical orthopaedic treatment of newborns with clefts--functional treatment with long-term effects.

AIM: Presentation of an orthopaedic/orthodontic treatment protocol within the framework of complex rehabilitation of patients with clefts of lip, alveolus and palate. Presurgical orthopaedic treatment aims at reduction of cleft size by guiding growth and functional rehabilitation. Long-term results of maxillary development and occlusion at young adult age are reported. PATIENTS AND METHODS: 43 newborns with unilateral (19) or bilateral (24) clefts of lip, alveolus and palate were examined until their deciduous dentition was complete. In 29 patients a late follow-up was performed at age 17.3 years (mean). Maxillary dental casts were evaluated prior to and following presurgical orthopaedic treatment at the time the deciduous dentition was complete and at young adult age (2 to 5 years after termination of orthodontic treatment). Parameters were width of the alveolar and palatal cleft as well as width and length of the dental arch. In the adults occlusion was studied and the occlusal outcome was related to the therapeutical input. RESULTS: Presurgical orthopaedic treatment reduced the cleft width by taking advantage of normal growth. At the age of 3 to 4 years the development of the upper dental arch was in line with that of non-cleft children. CONCLUSION: Maxillary growth may be guided in almost physiological terms even in patients with a cleft of lip, alveolus and palate. Prerequisite is functional rehabilitation by means of orthopaedic treatment at age 1 to 12 months in terms of functional orthodontic therapy and a surgical protocol saving tissues with growth potential.

Epidemiology of Hoffmeister's "genetically determined predisposition to disturbed development of the dentition" in patients with cleft lip and palate.

OBJECTIVE: Type and prevalence rates of the symptoms of Hoffmeister's "genetically determined predisposition to disturbed development of the dentition" were studied in patients with clefts. PATIENTS: Data of 263 patients with nonsyndromic clefts of lip (alveolus and palate) or isolated cleft palates were examined in a retrospective study. SETTING: The clefts were classified as cleft lip or cleft lip and alveolus, cleft palate, unilateral cleft lip and palate, and bilateral cleft lip and palate. All patients were scrutinized for 28 individual symptoms. Prevalences of the individual symptoms were statistically evaluated regarding cleft type and gender by using the chi-square test and were also compared with findings in patients without clefts. RESULTS: In 97.7% of the patients with clefts, at least one symptom was found. Microdontia of individual teeth, hypodontia, and hyperodontia were the symptoms most frequently recorded. Comparison of the different cleft types revealed differences regarding the prevalences of supernumerary lateral incisors (p = .051), infraposition of deciduous molars (p < .001), and atypical tooth bud position (p = .030). Comparison of the prevalences of 10 symptoms recorded in the patients with clefts with the prevalences recorded in patients without clefts showed nine symptoms were found much more frequently in the population with clefts. CONCLUSION: These findings support the hypothesis that clefting is part of a complex malformation associated with other dental anomalies resulting from disturbed development of the dentition. Patients with clefts are also likely to present other deficiencies of dental development and tooth eruption in both dentitions, even in regions not affected by the cleft.

Epidemiology of Hoffmeister's genetically determined predisposition to disturbed development of the dentition in patients with true skeletal class III malocclusion.

AIM: The prevalence of symptoms of Hoffmeister's "genetically determined predisposition to disturbed development of the dentition" as studied in patients with true skeletal Class III malocclusion; results of the study were compared with those found in the scientific literature regarding samples from the normal population and from orthodontic patients. PATIENTS AND METHODS: The prevalence of 20 defined symptoms was evaluated in 120 patients with true skeletal Class III malocclusion. The patients were selected on the basis of a positive family history and on the presentation of typical characteristics of a skeletal Class III morphology in a lateral cephalogram. The mean age of the patients evaluated was 12.4 years. The patients' files, 1161 radiographs and plaster casts were analyzed. The prevalence of the individual symptoms was compared by means of the chi(2)-test (p < or = 0.05). RESULTS: 118 patients (98.3%) were found to have 292 symptoms of "genetically determined predisposition to disturbed development of the dentition". Increased distance between molar buds, atypical tooth bud position and atypical root shape were the symptoms recorded most frequently. With regard to the simultaneous existence of several symptoms, the combination of four such symptoms was most frequent (20.8%), followed by the combination of three symptoms (15.8%), and five symptoms (15.0%). Congenital hypodontia was found in 19.2% of the patients. CONCLUSION: It should be kept in mind for patients with true skeletal Class III malocclusion that this type of dysgnathia is most likely combined with other symptoms of disturbed development of the dentition. The higher prevalence of those symptoms found in patients with skeletal Class III malocclusion when compared with the normal population and other orthodontic patients renders orthodontic treatment of those patients more difficult and calls for comprehensive clinical and radiological examination prior to any treatment.

Orthodontic findings in the deciduous and early mixed dentition--inferences for a preventive strategy.

AIM AND METHOD: The aim of the present epidemiologic study was to obtain representative basic data on the frequency, extent and age-dependence of malocclusions in the deciduous and early mixed dentition. The developmental tendencies of specific malocclusions were investigated from the aspect of orthodontic prevention. The collective comprised 8,864 preschool and school-aged children, of whom 1,225 were in the deciduous dentition (mean age 4.5 years) and 7,639 in the mixed dentition (mean age 8.9 years). The orthodontic data were clinically assessed as sagittal, transversal, or vertical single-arch and occlusal findings. In addition, the malocclusions were classified according to their primary symptoms. Early infantile habits, tongue dysfunctions, speech defects and incompetent lip closure were registered separately. RESULTS: 57% of the children were found to have malocclusions, with the frequency rising statistically significantly in dependence on age from the deciduous to the mixed dentition (p < or = 0.001). The mean extent of excessive overjet increased significantly from the deciduous to the mixed dentition. Crossbite with mandibular midline discrepancies were observed significantly more frequently in the deciduous dentition. Although the frequency of anterior open bite underwent a significant decline from the deciduous to the mixed dentition, open bite was the malocclusion most frequently associated with dysfunction in both groups. The significant increase in traumatic deep bite in the mixed dentition indicates an unfavorable developmental tendency in this anomaly until after the eruption of the permanent incisors. CONCLUSION: The need for preventive orthodontic therapy and for the intensified application of interceptive and early treatment measures is stressed in view of the high number of malalignments and malocclusions in the deciduous and mixed dentition and the tendency for some forms of malocclusion to deteriorate as the dentition develops.

Epidemiological significance of Hoffmeister's "Genetically determined predisposition to disturbed development of the dentition".

BACKGROUND AND AIM: Hoffmeister was the first to recognize the common genetic origin of structurally very varied disturbances in the development of the dentition. He coined the term "microsymptoms of a genetically determined predisposition to disturbed development". The purpose of the present study was to examine the incidence of those microsymptoms in a group of patients undergoing orthodontic treatment. PATIENTS AND METHODS: The orthodontic findings in 4208 patients were evaluated, and nine characteristic symptoms were registered with reference to the panoramic and other radiographs and to the patients' records. RESULTS: 1297 patients (30.8%) were found to have one or more symptoms of genetically determined predisposition to disturbed development. The most frequent symptoms were atypical position of tooth buds (12.2%), absence of tooth buds of permanent teeth (9.2%), and displaced teeth (7.0%). 73.5% of the patients had only one symptom, and 26.5% two or more. Microdontia and displaced teeth were associated particularly frequently with other symptoms of predisposition to disturbed development. Genetically determined predisposition to disturbed development of the dentition is accordingly not rare but is of great epidemiological significance and may provide early indications of potential developmental disorders such as missing tooth buds or displacement of teeth.

Maxillary canine displacement and genetically determined predisposition to disturbed development of the dentition.

BACKGROUND: The relationship between maxillary canine displacement and the simultaneous occurrence of "genetically determined predisposition to disturbed development of the dentition" as defined by Hoffmeister was investigated in 675 patients. PATIENTS AND METHODS: Panoramic radiographs taken of each patient during the first and the second mixed dentition periods were evaluated. Canine inclination and the distance between the tip of the canine and a line connecting the cusps of the molars were computed in five different age groups according to Dausch-Neumann. RESULTS: Statistical analysis revealed 34 patients with "potential canine displacement", who exhibited further symptoms of "genetically determined predisposition to disturbed development of the dentition" significantly more frequently than the total group. The symptoms concerned were agenesia, displaced tooth buds, rotated or tilted incisors, aplasia and microdontia of lateral incisors. CONCLUSION: Careful follow-ups in patients with a predisposition to disturbed dental development enables risks to be anticipated and canine displacement to be detected at an early stage.