Infraocclusion of primary molars: an epidemiologic and familial study.

The prevalence of infraocclusion of primary molars was studied in 1059 Swedish children aged 3-12 years with an even distribution between the age groups. No extractions were performed due to infraocclusion. 94 children (8.9%) showed infraocclusion of primary molars. Infraocclusion was found from 3 years of age. The prevalence varied between age groups, with a maximum of 14.3% in 8- and 9-year-old children and a minimum of 1.9% in 12-year-old children. 49 children had a single tooth in infraocclusion. The primary mandibular molars were affected more than 10 times as often as the maxillary. The prevalence of infraocclusion of the primary mandibular second molar showed a similar pattern but with a 1-2-year delay, up to a maximum in 9-year-old children. After this age the mandibular second molar was the tooth most commonly found ion infraocclusion. In a study of 138 3-12-year-old siblings of 109 children with infraocclusion the prevalence of infraocclusion was found to be 18.1%. When compared with the frequency in the total material (8.9%), the difference proved to be significant, supporting the hypothesis that there is a familial tendency in infraocclusion of primary molars. The mode of inheritance is discussed and it is concluded that the most likely explanation is that the condition is inherited on a multifactorial basis.

Longitudinal study and analysis of clinical supervision of maxillary canine eruption.

In 505 Swedish schoolchildren, the need to supervise the eruption of the maxillary canines was assessed by digital palpation and related to occlusal development and somatic maturity. The aim was to judge the extent to which clinical methods should be supplemented with radiographic methods. The 505 children, aged 8-12 yr, were clinically investigated and the eruption was followed over a 3-yr period. The age of the child was found not to be a valid criterion for radiographic investigation of the canine position. The investigation showed that 29% of 10-yr-old children had non-palpable canines bilaterally. In 11-yr-old children, the corresponding figure was 5%. A palpable buccal bulge in the primary canine apical area was found to signify a favorable eruption position. The prevalence of non-palpable or unerupted canines was 3% in the age group 11-15 yr. Indications for radiographic examination of canine position were present in altogether 7% of the children over 10 yr of age according to the clinical diagnostic criteria used.

Osseointegrated implants in the oral habilitation of a boy with ectodermal dysplasia: a case report.

The most characteristic oral feature in ectodermal dysplasia is hypodontia. Children and adolescents suffering from ectodermal dysplasia often need extensive and complicated prosthetic treatment. The development of techniques for osseointegrated implants offers new possibilities for the oral habilitation of these children. This paper describes the oral habilitation of a boy with severe ectodermal dysplasia and where Brånemark osseointegrated implants have been used as part of the treatment. The patient was seen at the dental department at the age of 1.5 years. Two conically-shaped upper incisors were at that time the only teeth that had erupted. The treatment was planned in a multidisciplinary odontological group involving paediatric dentistry, orthodontics, prosthodontics, oral surgery and maxillofacial radiology. At the age of 3 years it was verified that the boy had four primary teeth (53, 51, 61, 63) and four permanent teeth (16, 11, 21, 26). There were no teeth in the lower jaw. The alveolar ridges in the edentulous areas were low or missing. During the period 3-6 years of age the boy used an upper partial denture adapted to allow the mesial drift of the 16 and 26 teeth. At the age of 6 years, two Brånemark implants were inserted in the lower front-cuspid region. A specially designed overdenture for the lower jaw was constructed. The overdenture was retained in contact with the male attachments by two cuffs of heat-polymerized resilient silicone. Over the next 4 years the dentures were modified due to the eruption of permanent teeth and growth. However, only minor corrections were necessary concerning the retention system of the lower denture. The implants are well osseointegrated and stable and allow the boy to use a lower denture without any complications.

Proximal alveolar bone level after orthodontic treatment with magnets, superelastic coils and straight-wire appliances.

Proximal alveolar bone level changes were radiographically determined in 20 subjects (mean age 14.3 years, SD 2.00) a short time after rapid orthodontic treatment with magnets and superelastic nickel-titanium coils succeeded by straight-wire appliances. The findings were compared with a matched control group of 20 individuals (mean age 14.3 years, SD 1.99) who had no history of orthodontic treatment. Proximal alveolar bone level changes were determined on bitewing radiographs as the distance between the cementoenamel junction (CEJ) and the alveolar bone crest (AC). The observation period was 2.7 years (SD 0.65) for the treatment group and 2.8 years (SD 0.65) for the control group. In the treatment group, a small mean increase of 0.2 mm (SD 0.29) in the CEJ-AC distance was found a short time after treatment. In the control group the increase in CEJ-AC distance was 0.1 mm. The difference between the groups was significant (P < 0.001). In the treatment group, sites in the maxilla showed significantly greater CEJ-AC distances than in the mandible (P < 0.001), 0.3 mm (SD 0.33) versus 0.1 mm (SD 0.24). The mesial sites of the maxillary first molars in the treatment group showed the highest average increase in distance between CEJ and AC, mean 0.5 mm (SD 0.33). Neither group had any sites with bone loss, i.e., CEJ-AC distance exceeding 2 mm. No significant difference was found in CEJ-AC distance between teeth moved with magnets succeeded by straight-wire appliances and teeth moved with superelastic coils succeeded by straight-wire appliances.

Incisor resorption caused by maxillary cuspids. A radiographic study.

A detailed radiographic study of 46 cases of maxillary incisor resorption related to unerupted cuspids finds most resorption in midroot, with about half on labial or lingual surfaces where it was not detectable on periapical radiographs. Resorption appears early, making it desirable to evaluate cuspid position no later than 10 or 11 years of age.

Incisor root resorptions due to ectopic maxillary canines imaged by computerized tomography: a comparative study in extracted teeth.

The purpose of the study was to analyze the ability of computerized tomography (CT) scanning to discriminate maxillary incisor root resorptions caused by ectopically erupting canines. Seventeen maxillary incisors were radiographed in vivo by CT scanning. Contiguous transverse CT scans with a slice thickness of 2 mm were exposed perpendicular to the long axis of the lateral incisors and through the crown of the adjacent, ectopically positioned maxillary canine. Each scan was analyzed and the resorptions on the roots of the laterals were graded according to the maximum depth of the cavity. After the lateral incisors were extracted they were clinically inspected, photographed in different light settings and views, and probed at the contact area between the laterals and the canines. The assessment of the extent of resorption in 4 stages on the CT images compared with the in vitro observations of the extracted roots showed a high degree of agreement for the extent of loss of root substance for all teeth. We conclude that CT scanning performed with good technique accurately reveals tooth root resorption. The presence and influence of the inherent artifacts of tooth root resorption on CT scans are discussed.

Infraocclusion of primary molars with aplasia of the permanent successor. A longitudinal study.

Infraocclusion of deciduous molars that also lack a permanent successor is found to progress more than where a successor is present, while exfoliation is severely retarded. The aplasia is the most important factor in treatment planning and timing.

Repelling magnets versus superelastic nickel-titanium coils in simultaneous distal movement of maxillary first and second molars.

Eighteen subjects, aged 12.5 to 18.3 years, with Class II malocclusion, deep overbite and moderate space deficiency in the maxilla were treated orthodontically using repelling rare earth magnets on one side and superelastic nickel-titanium coils on the contralateral side for simultaneous distalization of maxillary first and second molars. The force values of the magnets and the coils were calibrated to 225g at the start of treatment and when reactivation was performed every fourth week. Tooth movement was analyzed by measuring dental casts, lateral photographs of dental casts, and lateral skull radiographs before and after 6 months of treatment. Mean distal molar movement was 3.2 mm for the supercoils and 2.2 mm for the magnets. Mean reduction of the overbite was 3.6 mm. Complaints of discomfort were more frequent for the magnet sides. The results indicate that superelastic coils are more effective than repelling rare earth magnets in molar distalization.

Hyalinization and root resorption during early orthodontic tooth movement in adolescents.

The aim of this investigation was to study the hyalinization of the periodontal ligament with time and its relationship to root surface resorption after the application of an orthodontic force, reactivated weekly, of 50 cN (approximately 50 g). Fifty-six patients (18 boys and 38 girls, mean age 13.8 years) were divided into 7 groups of 8. In each patient, one premolar was moved buccally 161 with a fixed orthodontic appliance. The contralateral premolar served as a control. The experimental periods ranged from 1 to 7 weeks. Local areas of overcompression in the periodontal ligament were recorded in 33 test teeth (59%) and 2 controls (4%). Hyalinization was seen in all experimental groups, more often after the first 4 weeks of force application. Hyalinized areas were recorded opposite an intact root surface (54%) or close to and just apical or coronal to an area of root resorption (45%), and were usually located buccocervically and linguoapically, corresponding to expected pressure zones of the periodonal ligament.

Orthodontic maxillary expansion and its effect on nocturnal enuresis.

A previous retrospective study of 10 children with varying degrees of nocturnal enuresis has shown that one side effect of rapid maxillary expansion (RME) is spontaneous reduction in bed-wetting at night. The aim of this prospective study was to analyze the effect of RME treatment (mean 2 weeks) in cases of chronic, long-standing nocturnal enuresis. Ten children, 8 to 13 years old, who had not responded to conventional medical treatment for bed-wetting, were referred from the pediatric department. Within 1 month of RME of 3 to 5 mm, 4 children were completely dry and 3 showed notable improvement. The results are encouraging, especially given the spontaneous recovery rate of about 15% per year. A reduction in nocturnal enuresis in children has also been reported after tonsillectomy. However, in this pilot study, no significant associations could be found between improvement in nocturnal enuresis and improvement in the nasal airway, age, amount of expansion, or nasopharyngeal dimension (measured on cephalograms).

Continuous versus interrupted continuous orthodontic force related to early tooth movement and root resorption.

The aim of the present clinical investigation was to assess the effects of continuous and interrupted continuous forces of the same magnitude (50 cN = 50 g) on orthodontic tooth movement and related adverse tissue reactions, i.e., root resorption. Thirty-two maxillary first premolars in 16 patients, 8 boys and 8 girls (mean age 13.9 years), were moved buccally by means of a fixed orthodontic appliance with a sectional arch. The patients were divided into two groups of 8, for experimental periods of 4 and 7 weeks. The continuous force was checked and reactivated weekly to 50 cN. The interrupted continuous force applied to the contralateral premolars was left uncontrolled for 3 weeks, after which the arch was made passive for 1 week for tissue rest and recovery. Tooth movements were studied on dental casts using a coordinate measuring machine (Validator 100, TESA SA, Renens, Switzerland). Horizontal tooth movement with continuous force was more effective than with interrupted continuous force after 7 weeks. Histological sections of the experimental teeth, however, showed no difference in the amount or severity of root resorption between the two forces. Individual variations in both the magnitude of tooth movement and the amount and severity of root resorption for both of the two force systems were great.

Repair of orthodontically induced root resorption in adolescents.

The aim of this investigation was to study the reparative potential of orthodontically induced root resorption. Sixty-four maxillary right and left first premolars in 32 patients (15 boys and 17 girls, mean age 13.7 years) were moved buccally with fixed orthodontic appliances and a continuous force of 50 cN (approximately 50 g), activated weekly for 6 weeks. The patients were divided into 4 groups of 8. Retention periods varied from 1 week to 8 weeks. Histological preparations showed that root resorption affected all the test teeth. The percentage of resorptive areas that had begun to repair ranged from 28% after 1 week of retention to 75% after 8 weeks. The healing cementum was almost exclusively of the cellular type. Partial repair, with the resorption cavity walls only partially covered with cementum, was the most frequent type of repair during the first 4 weeks of retention (17% to 31%). Functional repair, with the total surface of the resorption cavity walls covered with varying thicknesses of cementum, dominated after 5, 6, 7 and 8 weeks of retention (33% to 40%). There were no large differences in the healing potential in the cervical, middle, and apical thirds of the root. After 8 weeks, three out of four resorptive areas showed some degree of repair. Individual variations in healing potential were large.

Ectopic eruption of maxillary first permanent molars in children with cleft lip.

The purpose of this study was to determine the incidence of ectopic eruption of the maxillary first permanent molars in cleft patients. Panoramic radiographs of 70 Brazilian Caucasian children, 6 to 8 years old and with complete unilateral cleft lip and alveolus, were assessed. Fourteen of 70 patients (20%) presented with ectopic eruption of one or both maxillary first permanent molars. Sixteen of 19 ectopically erupted molars (85%) were of a reversible type of ectopic eruption and 3 (15%) were irreversible. No significant differences were found between sexes or between cleft sides.

Infraocclusion of primary molars. An epidemiological, familial, longitudinal clinical and histological study.

The aims of this thesis were to estimate the prevalence and familial tendencies of infraocclusion of primary molars and analyse the effect of extraction on occlusal development, and to characterise histologically the ankylosis in infraoccluded primary molars and recommend guidelines for treatment. The thesis is based on five investigations. In the prevalence and familial studies, 1059 children and 138 first-degree sibs were investigated. The three longitudinal clinical studies comprised 215 primary molars in infraocclusion and the children were subjected to clinical and radiographic examination and analysis of model casts every six months. The histological study comprised 62 teeth in infraocclusion and 40 in normal positions. In addition, bone biopsies were analysed histologically and by enzyme histochemical methods. The prevalence of infraocclusion of primary molars was found to be age-related and was significantly higher in sibs than in the studied population, which indicates a familial tendency. Infraoccluded primary molars with a successor present generally exfoliated normally. The permanent successors usually erupted six months later than on the normal contralateral side. Extraction of primary molars in infraocclusion meant definite space loss in some cases. With aplasia of the successor, the infraoccluded tooth did not exfoliate within the normal time range and the root resorption was found to be very slow, especially after 12-13 years of age. Very few of the previously reported negative effects of non-treatment of primary molars in infraocclusion on exfoliation, eruption and occlusal development could be confirmed in this study. Most infraoccluded primary molars were ankylosed histologically. No differences were found in the bone biopsies from the infraoccluded and control group. The results indicate that ankylosis in infraoccluded primary molars is not a static condition but part of a remodelling process following normal resorption of the roots. The general treatment policy should be to wait for normal exfoliation of infraoccluded primary molars to take place if the permanent successor is present and in cases with aplasia consider the aplasia per se, the degree of primary root resorption and the risk of progression of the infraocclusion.

Symptoms and signs of temporomandibular disorders before, during and after orthodontic treatment.

The relationship between orthodontic treatment and symptoms and signs of temporomandibular disorders (TMD) was studied prospectively and longitudinally in 65 adolescent girls with Class II malocclusion. The subjects received orthodontic fixed appliance treatment with the straight-wire technique combined with or without extractions and were examined for symptoms and signs of TMD before, during, after, and finally one year post-treatment. Both symptoms and signs of TMD showed considerable fluctuations over the three-year period within the individuals. The general tendency was a decreased prevalence of symptoms of TMD over the three years. The prevalence of pain on mandibular movement and tenderness to palpation of the masticatory muscles was significantly less common during and after orthodontic treatment than before. Clinically registered TMJ clicking increased slightly over the three year period. One orthodontic treatment effect when normalizing Class II malocclusions with fixed appliances was a decreased prevalence of functional occlusal interferences. We concluded that the orthodontic treatment either with or without tooth extractions did not increase the risk for TMD or worsen pre-treatment signs of TMD. Subjects with Class II malocclusion and pre-treatment signs of TMD of muscular origin seemed rather to benefit functionally from orthodontic treatment in a three-year perspective.

The effect of a low fluoride containing toothpaste on the development of dental caries and microbial composition using a caries generating model device in vivo.

The purpose of the study was to evaluate the effect of daily use of a low fluoride containing toothpaste (250 ppm F) on the uptake of fluoride and development of enamel lesions as well as the prevalence of lactobacilli and mutans streptococci in dental plaque compared to the use of placebo toothpaste. 16 children were selected with homologous premolar teeth. The teeth were cemented with orthodontic bands ad modum Ogaard for plaque accumulation and enamel lesion development. The plaque accumulated during 4 weeks was collected and analysed for lactobacilli and mutans streptococci. The teeth were further analysed by secondary ion mass spectrometry (SIMS), determining the concentration profiles of fluoride and other elements in the outermost enamel and in the lesion. The results show that although significant amounts of fluoride were taken up in the surface enamel from the fluoride toothpaste, the extent of the lesions was not influenced compared to teeth brushed with a non F-toothpaste. Neither were microbiological differences in the dental plaque found between the groups. An interesting observation was that early demineralization of enamel took place without detectable levels of mutans streptococci in the overlaying dental plaque. The conclusion is that fluoride taken up in enamel from F-toothpaste has no significant influence on enamel lesion development if a cariogenic dental plaque with high levels of acid producing microorganisms is continuously attached to the enamel surface.

Orthodontic treatment standards in a public group practice in Sweden.

The aim was to assess the orthodontic treatment service provided by 6 orthodontists in a group practice in Malmö. One hundred cases were randomly selected from the model store. The Index of Complexity, Outcome and Need (ICON) was used to assess the need, complexity of the problem, outcome, the degree of improvement and whether the completed case was acceptable or not. The reliability of the examiner using the ICON was assessed using Root Mean Square. Logistic regression analysis was employed to explore the variables related to acceptability of the finish and duration of treatment. The younger the patient at the start of treatment the lower initial ICON score, with short treatment duration were associated with an acceptable finish. Three out of 100 cases were deemed as not requiring orthodontic treatment and 36 cases were classified as very difficult to treat. Nevertheless, 71 cases out of the 100 exhibited acceptable finishes with 27 indicating substantial or great improvement. 6 cases finished treatment with ICON scores greater than 43 indicating need for orthodontic treatment. The treatment on average took 22 months. An objective appraisal of the quality of orthodontic care in a group practice in Malmö has been undertaken. Seventy-one cases were completed with acceptable occlusions. The Index of Complexity, Outcome and Need appears to be a valuable tool to assess the multiple facets of orthodontic provision.

Class II correction with magnets and superelastic coils followed by straight-wire mechanotherapy. Occlusal changes during and after dental therapy.

The investigation comprised 18 consecutively selected patients, mean age 14.7 years at the start of treatment, with Class II malocclusion, deep overbite and space deficiency in the maxillary arch. The first phase of the treatment consisted of 6 months simultaneous distal movement of maxillary first and second molars with repelling samarium-cobalt magnets on one side and a superelastic nickel-titanium coil on the contralateral side together with an anterior biteplane to achieve bite opening. For the second phase of the treatment, a straight-wire appliance was used for an average treatment time of 1.3 years. Lateral head radiographs and dental casts were available at the start of treatment, after molar distalisation, at the end of treatment and 1 year post-treatment. The treatment resulted mainly in dental changes. The dental Class II molar relation was corrected to Class I by bodily distal movement of maxillary molars and by mesial movement of the mandibular molars. The correction of molar relation was significantly greater on coil sides than on magnet sides, mean 3.4 mm, and 3.0 mm, respectively. Despite anchorage loss associated with the maxillary molar movement, i.e. mesial movement of the maxillary incisors (mean 1.8 mm), the net overjet was reduced, mean 2.5 mm, by the use of Class II elastics. The average net improvement of bite opening was 2.6 mm, mainly due to extrusion of mandibular and maxillary molars. During the 1-year post-treatment period no significant dental or skeletal changes were found. The long-term implications of the treatment results need further consideration.

Orthodontic appliances in relation to nickel hypersensitivity. A review.

Nickel hypersensitivity is an increasing problem in adolescents, especially in girls, with a prevalence of up to 30%. The presence of nickel in orthodontic appliances and the possibility of causing nickel hypersensitivity has been discussed in case reports. A review of the literature concerning nickel hypersensitivity in relation to orthodontic appliances has shown that the risk is very low for patients who are not nickel hypersensitive at the start of the treatment. A patient who is already nickel hypersensitive at the start of orthodontic treatment may in rare cases show adverse reactions induced by the appliance. The slow long-term release of nickel from orthodontic appliances may induce tolerance to nickel in individuals who are not hypersensitive at the start of orthodontic treatment.

Mandibular incisor stability after bimaxillary orthodontic treatment with premolar extraction in the upper arch.

To evaluate long-term changes in the lower incisor region, a comparison was made between children with large overjet treated with extraction of the upper first premolars and fixed appliances in both jaws and untreated children with normal occlusion. The treatment group consisted of 26 children and was studied with plaster models on 5 occasions: before treatment, at the end of active treatment, at the end of retention, after 1 year out of retention and at the last registration 4 to 5 years out of retention. The total time from the start of treatment to the last registration was 9 years and 10 months. Cephalometric registrations were made at the first and last registrations. The group of untreated children, the control group, consisted of 19 individuals. They were also studied with plaster models and lateral headfilms during a period of 10 years. The age of the treatment group and the control group at the last registration was 21.7 years and 20.4 years, respectively. At the first registration there was an available space in the lower anterior region of -0.06 mm (+/- 1.73) in the treatment group and + 0.4 mm (+/- 2.00) in the control group. At the last registration the available space for the treatment group was -1.4 mm (+/- 1.31), an extra space loss of 0.8 mm; in the control group the space loss was 1.3 mm and the available space was thus -0.9 mm. No significant difference in anterior lower jaw crowding could be seen between the treatment and control group at the last registration. Subjective ranking of the plaster models from the final registrations according to the amount of crowding in the lower anterior region showed no significant difference between the treatment and the control group.