Characteristics of incisor-premolar hypodontia in families.

Nonsyndromic tooth agenesis is a genetically and phenotypically heterogenous condition. It is generally assumed that different phenotypic forms are caused by different mutated genes. We analyzed inheritance and phenotype of hypodontia and dental anomalies in 214 family members in three generations of 11 probands collected for genetic linkage study on incisor-premolar hypodontia (IPH). Our analysis confirms the autosomal-dominant transmission with reduced penetrance of IPH. The prevalence of hypodontia and/or peg-shaped teeth was over 40% in first- and second-degree relatives and 18% in first cousins of the probands. Four of nine noted obligate carriers of hypodontia gene had dental anomalies, including small upper lateral incisors, ectopic canines, taurodontism, and rotated premolars. These anomalies were also observed at higher than normal frequency in relatives affected with hypodontia. We conclude that incisor-premolar hypodontia is a genetic condition with autosomal-dominant transmission and that it is associated with several other dental abnormalities.

Orthopedic cervical headgear with an expanded inner bow in class II correction.

Forty consecutively referred children, 20 boys and 20 girls, with a Class II division I malocclusion and protrusive maxilla were treated with orthopedic cervical headgear with a 10 mm expanded inner bow and a long outer bow bent 15 degrees upwards. The mean age of the children at the beginning of treatment was 9.3 years (SD 1.3, range 6.6 to 12.4 years), and the average treatment time was 1.8 years (SD 0.6, range 0.8 to 3.1 years). In all patients Class II molar relationships were successfully corrected to Class I molar relationships. This was accompanied by a marked widening of both maxillary and mandibular dental arches. The cephalometric analysis suggested that the observed improvement of the occlusion was due to an inhibition of forward growth of the maxilla and anterior downward rotation of the palate.

Dental maturity in Finns and the problem of missing teeth.

Development of teeth was studied from 2483 dental panoramic tomograms of 1651 healthy Finns ranging in age from 2 to 25 years. Dental maturity was assessed using a method based on developmental stages of 7 left mandibular teeth. We give sex-specific tables of maturity scores as a function of ages and of ages as a function of maturity scores. Also generated are percentile graphs for visual evaluations of dental maturity in children and adolescents. Since maturity scales do not tolerate any missing data, a great limitation for their use, we have developed linear regression models for predicting the formation stages of each of the 7 mandibular teeth. It was easiest to predict the formation stage of the mandibular first molars (correct in 87% within the study material) and most difficult to predict second molars and second premolars (correct in 69% and 70%, respectively). We expect the data and formulae presented in this study to prove useful in research and in clinical and forensic dentistry.

Comparison between cephalometric classification methods for sagittal jaw relationships.

The present study evaluated how 2 widely used cephalometric sagittal analyses, ANB angle and WITS appraisal, classify skeletal classes I, II, and III in a random selection of 497 Finnish boys aged 4-20 years. This distribution was also compared with the visual inspection of cephalometric structures judged by 2 university instructors in orthodontics. The results showed remarkable differences and even sparked controversy concerning classification of the sagittal jaw relationships. The ANB angle and the WITS appraisal emphasized the role of class II based on a failure to distinguish the proportion of class I. The low-angle influence skewed the distribution of the ANB pattern in the class III direction, and the WITS pattern, conversely, towards class II. High- or low-angle influence had only minor effects on the visual inspection of cephalometric structures. This cross-sectional study showed an age-related decreasing mean value for the ANB angle and increasing mean value for the WITS appraisal, thus explaining the remarkable difference in the distribution of sagittal classes. However, the findings of age-related changes makes the use of the fixed norms questionable. For extreme or controversial cephalometric interpretations, visual inspection provides an essential aid in diagnosis and skeletal classification.

Changes in dental arch dimensions by use of an orthopedic cervical headgear in Class II correction.

Orthopedic cervical headgears are commonly used in Finland for early treatment of the Class II malocclusion, but there is a lack of follow-up studies on the effect of this treatment. We have evaluated the effects of the cervical headgear therapy with an expanded inner bow to treat Class II malocclusion and dental arches. Forty children, 20 boys and 20 girls, with Class II, Division 1 malocclusion, were treated with the orthopedic cervical headgear. No other appliances were used. The mean age of the subjects in the beginning of the treatment was 9.3 +/- 1.3 years (range 6.6 to 12.4 years). The mean treatment time was 1.8 +/- 0.6 years (range 0.8 to 3.1 years). The cervical headgear was used with a 10 mm expanded inner bow and a 15 degrees upward bend of the long outer bow, 12 to 14 hours a day with a force of 500 gm per side. Class I relationships were achieved in all subjects. At the same time, the maxillary and mandibular dental arches were widened. The annual increment in the intercanine and intermolar distances was significantly greater than in healthy control subjects (literature data), except for the mandibular intercanine distance in boys. The maxillary arch lengths were also significantly increased; there were no consistent changes of the mandibular arch lengths. Class II malocclusion may be treated with the orthopedic cervical headgear. The treatment results in increased growth of the dental arch widths by expansion of the inner bow of the headgear. The widening of the maxilla is followed by spontaneous widening of the mandible.

Age and skeletal type-related changes of some cephalometric parameters in Finnish girls.

The aim of the present study was to define some cephalometric standards in a group of 217 Finnish girls from 7.0 to 18.0 years of age and furthermore to estimate the influence of the skeletal classes on these standards. Age-related changes were seen between the standards of the youngest (7.0-9.5 years) and the oldest (14.5-18.0 years) group where 9 out of 15 of the inspected angles increased with age, three of them ANPr***, SNPg** and SNB* significantly, and 6 decreased, four of them significantly: ANPg***, ANB**, NL/ML* and RL/ML*. The cranial base angles did not show any significant age-related or skeletal type-related variations. Between the skeletal groups I and II significant differences were seen in 11 variables. Between skeletal I and III groups, 7 angles were significantly different. The results demonstrate that when cephalometric standards are used, they should be derived from that population, they should be age related, and the skeletal pattern should be taken into account.

Atherosclerosis precursors in Finnish children and adolescents. XIV. Zinc and copper concentrations in deciduous teeth.

Zinc and copper concentrations were analysed from cariesfree deciduous teeth of 125 Finnish children, 6-7- and 9-10-year-olds, from three cities. Enamel and dentine were separated and prepared into pills which were analysed individually with the proton induced x-ray emission spectrometry (PIXE) method. The total mean (+/- SD) zinc concentrations for enamel and dentine were 143 +/- 31 and 133 +/- 36 ppm, respectively, and are in agreement with the values reported recently. The median copper concentration for enamel was 0.54 ppm with a range from 0.0 to 4.29 and for dentine 0.27 ppm with a range from 0.0 to 3.60 being among the lowest reported. The low copper values are interesting as to the possible association with the development of atherosclerosis. Geographical differences were noted between the zinc concentrations of the three cities, the children of Helsinki having significantly higher zinc values than the children of Kuopio and Oulu. No linear correlation was found between zinc and copper concentrations at the individual level.

Lead concentrations of enamel and dentine of deciduous teeth of children from two Finnish towns.

The proton-induced x-ray emission method was used to analyze lead concentrations in enamel and dentine of deciduous teeth of 105 6- and 9-yr-old children living in two Finnish towns. Helsinki, the capital city, was assumed to represent high lead exposure and Kuopio, a country town in the middle of Finland, low or moderate lead exposure. In all but two teeth the enamel contained higher lead concentrations than dentine. The individual enamel-dentine lead concentration ratio was not stable but varied greatly. The median dentine lead concentration for 9-yr-old children in Helsinki and Kuopio was 2.0 ppm and 2.9 ppm, respectively, and for 6-yr-old children was 2.5 ppm and 2.7 ppm, respectively. The enamel lead concentrations found in 9-yr-olds in Helsinki and Kuopio were 4.2 and 4.5 ppm, and in 6-yr-olds were 9.1 and 4.4 ppm, respectively. The results reveal low or moderate lead concentrations. Nevertheless, a twofold and statistically significant (P less than .01) increase was found in the enamel of Helsinki children born in 1974 compared with those born in 1971.

Influence of the modified Milwaukee brace on the dentofacial complex.

The influence of the Milwaukee brace treatment in a material of 56 patients, mean age 13.9 +/- 2.1 years, was studied. Thirteen of the patients wore monoblock and 46 did not, during the period of wearing the MW-brace, mean 0.9 years. Pre- and post-treatment cephalograms and study models were analysed. Small but significant detrimental changes were seen in about half of the 22 dentofacial variables analysed. Decreasing of the interincisors angle and the palatal vault height, and increasing of the ILs-SNL, ILs-MaxL and canine width were highly significant changes. Detrimental changes in the monoblock group occurred also but they were not as considerable as in the non-monoblock group. The influence of the five dentofacial characteristics which were analysed in more detail did not show any clear correlation to the magnitude of the change.

Evaluation of autotransplantations of completely developed maxillary canines.

Transplantation of 28 maxillary canines was followed up in 22 patients with an average age of 25.2 s.d. 9.9 years. The root was fully developed. The mean immobilization time was 6.6 weeks and the mean follow-up period 17.8 months. Results seemed to be better in the age group of 13--20 years than in 21--30 and 31--47 years. Statistically significant better results were found in the youngest than in the older groups in the return of vitality, vertical bone resorption, periodontal space in the lamina dura. Four of the 28 teeth were extracted because of great mobility caused by poor bone regeneration and vertical resorption of the alveolar bone: three in the middle age group and one in the oldest. Pulp extirpation was performed on nine teeth: six in the oldest group and three in the middle group. Vitality returned in only three teeth, all of which belonged to the youngest group. Root resorption was observed in all age groups; in 76% of the cases it occurred in the apical third, and was generally inflammatory. The causes of the failure of transplantation were considered to include damage of the transplant during removal from deep palatal malposition, poor regeneration of the bone around the transplant and chronic periodontal infection. The prognosis for transplantation was found to be fairly good for patients under 20 years of age but poorer for older age groups.

Determination of the gonial angle from the orthopantomogram.

This study demonstrates that the size of the gonial angle can be determined from the orthopantomogram with the same degree of accuracy as from the generally used lateral cephalogram, the gonial angle being formed by the tangents of the lower border of the mandible and the distal border of the ascending ramus and the condyle on each side. It also shows that the right and left gonial angles can be quite easily determined individually from orthopantomograms, thus avoiding the disturbing influence of the superimposed images found on lateral cephalograms. It proves conclusively that the orthopantomogram is the more obvious choice for determination of the gonial angles.