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It has been shown that children born extremely preterm (EPT) often suffer from medical complications and growth restrictions in early childhood. Catchup growth diminishes these effects but the children are known to have lower weight, height, and head circumference as school children. Effects on enamel development have been shown. How this affects the dento-alveolar outcome during adolescence is not known. Forty EPT children with a gestational age (GA) of less than 29 weeks, at 12-16 years of age, and matched healthy controls born at term, with a GA of 37-43 weeks, were examined. Data from the clinical examination, dental casts, and bitewing radiographs were collected and compared. Malocclusion was noted, and dento-alveolar length, width, palatal height, and mesio-distal tooth width were measured. Medical diagnoses, neurological, and neuropsychiatric disturbances were noted at the time of the survey. The two groups were compared with an epidemiological normal reference material. The results showed no differences between the controls and reference material. Angle Class II was the most frequent malocclusion associated with morbidity, neurological, and neuropsychiatric disturbances, followed by deep bite and overjet. Three or more malocclusions were almost twice as common among the EPT children compared with the controls. Significantly smaller incisors, canines, and first molars were found. In summary, the EPT children, during adolescence, had medical aberrations as well as dento-alveolar effects opposed to the healthy children born at term. Dentists should be aware of this and treatment plans should be made in due time.

The aim of this work was to update the bibliography regarding the concept of 'temporomandibular disorder (TMD)' and 'posterior crossbite' and try to find out if there is any association between some special signs/symptoms of TMD and type of posterior crossbite. A literature search from 1970 to 2009, due to specified criterion, resulted in 14 publications that were found to be relevant for the present systematic review. An association between TMD and posterior crossbite (Yes-group) was reported as often as absence of such a relationship (No-group). The samples in the two groups showed similarities as well as differences with respect to number, gender, and age. Most articles reported only on 'presence' or 'absence' of crossbite and only few on type of crossbite opposite to a thorough account of clinical signs and symptoms of TMD. This review seems, however, to state that a functional posterior crossbite (mandibular guidance with midline deviation) is associated with headache, temporomandibular joint and muscular pain, and clicking. As evident from the discussion, such type needs orthodontic treatment to rehabilitate the asymmetric muscular activity between the crossbite and non-crossbite sides and the changed condyle/temporal relationship caused by mandibular deviation. Whether this treatment also will avoid future TMD problems can be answered only after clinical follow-up studies have been performed.

The aim of the present study was to examine dentoalveolar development in subjects with an 'ideal' (normal) occlusion. The material comprised 436 study casts of 189 male and 247 female subjects of Swedish origin between the ages of 5 and 31 years with no history of orthodontic treatment. Tooth width, and arch length, width, and depth, as well as palatal height were measured. The data were analysed with a Student's t-test. The results verified that continuous changes of the dental arches occur from the primary until the adult period, with individual variations. This change could be interpreted as a biological migration of the dentition, resulting in anterior crowding especially in the mandible, even in subjects with congenitally missing third molars. The occlusion should be regarded as a dynamic rather than a stable interrelationship between facial structures. This natural development has to be considered in orthodontic treatment planning as well as in assessment of stability following orthodontic treatment. A continuous increase of palatal height up to adulthood seems to be an effect of a slow continuous eruption of the teeth. This finding is also of significance in explaining the infraposition of implant-supported crowns.

This study was performed to establish age- and gender-specific cephalometric normative data for a Swedish population. The material comprised 469 lateral cephalograms from two groups of subjects of Swedish origin between 5 and 31 years of age. All subjects (males and females) were diagnosed as 'normal' according to specified criteria and with no history of orthodontic treatment. Lateral cephalograms and body height measurements were taken at 5, 7, 10 and 13 years of age in one group (group E) (longitudinal follow-up). The same registrations were made in the other group (group U) at 7, 10 and13 years of age (mixed longitudinal type). Those 13 year olds were re-examined at 16, 19 and 31 years of age (longitudinal follow-up). No significant differences between age groups in the two samples were found. Therefore, subjects of the same age were combined. The study is hence regarded as a longitudinal follow-up from 5 to 31 years of age. The subjects were also grouped into dental development stages to widen the applicability of the cephalometric data.The craniofacial distances were constantly larger in males than in females, while no statistical differences as regards angular measurements were seen between genders. Distances as well as angular measurements varied with the different developmental periods. The results clearly verify that facial pattern changes existed during the observation period, with a growth acceleration of most distances between the 13 and 16 year recordings.

The aim of the present study was to evaluate the long-term effect of implants installed in different dental areas in adolescents. The sample consisted of 18 subjects with missing teeth (congenital absence or trauma). The patients were of different chronological ages (between 13 and 17 years) and of different skeletal maturation. In all subjects, the existing permanent teeth were fully erupted. In 15 patients, 29 single implants (using the Brånemark technique) were installed to replace premolars, canines, and upper incisors. In three patients with extensive aplasia, 18 implants were placed in various regions. The patients were followed during a 10-year period, the first four years annually and then every second year. Photographs, study casts, peri-apical radiographs, lateral cephalograms, and body height measurements were recorded at each control. The results show that dental implants are a good treatment option for replacing missing teeth in adolescents, provided that the subject's dental and skeletal development is complete. However, different problems are related to the premolar and the incisor regions, which have to be considered in the total treatment planning. Disadvantages may be related to the upper incisor region, especially for lateral incisors, due to slight continuous eruption of adjacent teeth and craniofacial changes post-adolescence. Periodontal problems may arise, with marginal bone loss around the adjacent teeth and bone loss buccally to the implants. The shorter the distance between the implant and the adjacent teeth, the larger the reduction of marginal bone level. Before placement of the implant sufficient space must be gained in the implant area, and the adjacent teeth uprighted and paralleled, even in the apical area, using non-intrusive movements. In the premolar area, excess space is needed, not only in the mesio-distal, but above all in the bucco-lingual direction. Thus, an infraoccluded lower deciduous molar should be extracted shortly before placement of the implant to avoid reduction of the bucco-lingual bone volume. Oral rehabilitation with implant-supported prosthetic constructions seems to be a good alternative in adolescents with extensive aplasia, provided that craniofacial growth has ceased or is almost complete.

The aim of the study was to assess the prevalence of malocclusion in a population of Bogotanian children and adolescents in terms of different degrees of severity in relation to sex and specific stages of dental development, in order to evaluate the need for orthodontic treatment in this part of Colombia. A sample of 4724 children (5-17 years of age) was randomly selected from a population that attended the Dental Health Service; none had been orthodontically treated. Based on their dental stages the subjects were grouped into deciduous, early mixed, late mixed and permanent dentition. The registrations were performed according to a method by Björk et al. (1964). The need for orthodontic treatment was evaluated according to an index used by the Swedish National Board of Health. The results showed that 88 per cent of the subjects had some type of anomaly, from mild to severe, half of them recorded as occlusal anomalies, one-third as space discrepancies, and one-fifth as dental anomalies. No clear sex differences were noted, except for maxillary overjet, spacing, tooth size (all more frequent in boys), and crowding (more frequent in girls). Occlusal anomalies and space discrepancies varied in the different dental developmental periods, as did tipped and rotated teeth. Little need for orthodontic treatment was found in 35 per cent and moderate need in 30 per cent. A great need was estimated in 20 per cent, comprising children with prenormal occlusion, maxillary overjet, or overbite (> 6 mm), posterior unilateral crossbite with midline deviation (> 2 mm), severe crowding or spacing, congenitally missing maxillary incisors, impacted maxillary canines or anterior open bite (> 3 mm in the permanent dentition). Urgent need for treatment was estimated to be 3 per cent, comprising subjects with extreme post- and pre-normal occlusion, impacted maxillary incisors or extensive aplasia.

Based on observations of longitudinal changes in dental arch dimensions, it has been stated that an individuality of arch form and an integrity of this form exists. However, longitudinal studies evaluating arch form changes have rarely been reported in the literature. The purpose of this investigation was to use a computer-assisted method for the description and analysis of maxillary and mandibular arch form in a sample of normal occlusion subjects, and to evaluate the long-term stability in dental arch form from the age of 13-31 years. The study was carried out on 30 subjects of Scandinavian origin with normal occlusion, recorded at a mean age of 13.6 years and at follow-up at 31.1 years. Arch form analysis was based on a standardized photographic procedure, digitization of morphological landmarks, and a computerized form analysis in which arch form was described using eccentricity values of conics. No specific arch form could be found to represent the sample. Age changes occurred in arch form, although with large individual variations. For the mandible, a significant change to a more rounded arch form with age was found, which in males was accompanied by a significant increase in inter-molar distance and reduction in arch depth. There was also a significant correlation between change in mandibular arch form and increased irregularity of the lower incisors. These findings of lack of stability in arch form in normal occlusion subjects, when passing from adolescence into adulthood, further question the possibility of achieving stability post-orthodontically.

The prevalence of breathing obstruction was determined in a cohort of 4-year-old children. Craniofacial morphology was studied in obstructed children and compared with data from a control group of 4-year-old children with ideal occlusion. Dental arch morphology was compared in obstructed and non-obstructed children in the group. Parents of 95.5 per cent of the study base of 644 children answered a questionnaire concerning their child's nocturnal behaviour and related questions. The 48 children who, based on parental report, snored every night or stopped breathing when snoring (the 'snoring group'), showed a higher rate of disturbed sleep, mouth-breathing, and a history of throat infections as compared with the rest of the cohort. These children were examined by both an orthodontist and an otorhinolaryngologist and, when indicated, they were also monitored in a sleep laboratory. Twenty-eight of the children were diagnosed as having a breathing obstruction (4.3 per cent of the cohort) and six children (0.9 per cent) had sleep apnoea (mean apnoea-hypopnoea index of 17.3), using the same definition as that for adults. Cephalometric values among the obstructed children differed from those of a Swedish sample of the same age with ideal occlusion. Thy had a smaller cranial base angle and a lower ratio of posterior/anterior total face height. Small, but not significant differences were seen for NSL-ML and NL-ML. Compared with 48 asymptomatic children from the same cohort, the obstructed children had a narrower maxilla, a deeper palatal height, and a shorter lower dental arch. In addition, the prevalence of lateral crossbite was significantly higher among the obstructed children.

Seven glass-ionomer cements were tested and compared with a composite resin in order to find the glass-ionomer cement with the highest bond strength to enamel with normal anatomy and composition (not ground). Five types of surface treatment were used. The results show that Aqua Cem and Ketac Cem, both water-hardening, present the highest bond strength, followed by the conventional glass-ionomer cement Fuji IIF. Surface treatment according to the manufacturers' instructions and surface treatment with polyacrylic acid were found to give rise to the highest bond strength for all of the seven cements. However, none of the glass-ionomer cements reached the values for the composite resin Concise. The testing instrument designed for ex vivo purposes measured with high precision and accuracy and with a low methodological error.

The changes in craniofacial growth and development of dental occlusion were studied in children with juvenile chronic arthritis (JCA), and treatment with functional orthodontic appliances (activators) was tested in both JCA and healthy children with distal occlusion. Fifteen JCA children with Angle Class I occlusion and 15 JCA children with Angle Class II malocclusion were followed longitudinally and compared with 23 healthy children with Angle Class II malocclusion. The facial growth of the JCA children without need of orthodontic treatment mainly followed the normal pattern while the JCA children with Angle Class II malocclusion had a deviating facial morphology, which became more abnormal during growth. During the orthodontic treatment period a slight improvement was seen in mandibular positions in the sagittal and vertical planes in both treated groups, but the changes were more marked in the healthy children. None of the treated groups attained completely normal facial morphology, but in most children the occlusion improved and could be classified as normal. The morphology achieved by treatment largely remained the same during the follow-up period and relapse was seen only in a few children. JCA children with minor skeletal discrepancies can be satisfactorily treated during growth with functional orthodontic appliances, possibly in combination with fixed appliances. Even if skeletal changes in response to orthodontic treatment are rather limited, these changes combined with the improvement in dental occlusion obtained through treatment may result in better dentofacial aesthetics. Furthermore, jaw functions are likely to improve which also might benefit the patient from a psychosocial point of view.

In nine partially edentulous adult patients, mean age 47 years (range 17-64 years) 23 osseointegrated implants were used as orthodontic anchorage to perform the following types of orthodontic tooth movements: tipping, torquing, rotation, intrusion, extrusion, and those associated with bodily movements. The total orthodontic treatment period varied between 4 and 33 months (x = 17 months). Pre-operatively, at the start and end of orthodontic treatment, and at the annual controls, clinical as well as biometric and radiographic (panoramic, lateral cephalograms and periapical radiographs) recordings were performed. The osseointegrated anchorage units were used as reference points for measurements of two- and three-dimensional tooth movements with a co-ordinate machine. The 2-D tooth movements varied between 0.2 and 6.2 mm, whereas movements in the third dimension, extrusion and intrusion, ranged from 0.0 to 13.5 mm. The movement in space for the individual tooth was observed to be, as a mean, 3.9 mm (range 0.6-18.7 mm). However, the osseointegrated titanium implants (fixtures) used as orthodontic anchorage remained in position when orthodontically loaded for the various tooth movements. After completion of the orthodontic treatment the fixtures served as abutments for permanent prosthetic constructions.

In 15 adolescents (13 years 2 months-19 years 4 months) in the late dental stage, Brånemark implants (n = 27) were chosen to replace missing teeth due to congenital absence or trauma. The patients were followed for at least 3 years, at yearly intervals, biometrically and radiographically. No fixture losses occurred. Only minor loss of bone support at the fixtures was observed, while adjacent tooth surfaces showed some loss in some cases. Infra-occlusion of the implant restorations was noticed in patients with residual craniofacial growth. Thus, the dental and skeletal maturation, and not the chronological age of the patient, must be taken into consideration to avoid infra-occlusion of the fixture crown. Furthermore, it is important to gain enough space for the fixture in the mesio-distal direction, to avoid the risk of marginal bone loss at teeth that are adjacent to it.

The present study was performed in order to test the hypothesis that the height of supporting bone and connective tissue attachment will be maintained around teeth bodily moved into areas of reduced bone height. During a pre-experimental period, areas with markedly reduced bone height were produced in the mandible of 4 beagle dogs through extraction of the 4th premolars and subsequent surgical reduction of the bone height in the extracted sites to a level corresponding to half the root length of the 3rd premolar. Following healing, one of the third premolars was bodily moved in a distal direction into the area of reduced bone height, while the contralateral premolar served as a non-moved control. After 6 months of active tooth movement, the teeth were retained in their new position for a further 2 months before biopsies of test and control tooth sites were sampled. Radiographic evaluation showed that a bodily movement had been achieved with no or only minimal vertical displacement of the teeth. The histological analysis revealed that none of the teeth, orthodontically moved or not, had experienced loss of connective tissue attachment. Although a greater distance between the cemento-enamel junction and the bone crest was found on the pressure side of the orthodontically moved test teeth in comparison to the contralateral, non-moved control teeth, the bone level at all test teeth was more coronally positioned than the original, reduced bone level in the area into which the test teeth had been moved. Hence, these findings indicate that a tooth with a normal height of periodontal support can be orthodontically moved into an area of markedly reduced bone height with maintained height of the supporting apparatus.

The aim was to study if osseointegrated implants behave like teeth in the growing jaw. Six young pigs were used, one of them randomly selected as a control. The test pigs received four fixtures each in regions with various dento-alveolar development. The biometric and radiographic findings, after an experimental period of 165 days, showed that the osseointegrated implants do not become secondarily displaced in sagittal and transversal dimensions and, thus, do not behave like normal teeth. Consequently, the osseointegration technique is not to be recommended in the lateral regions in young children.

Chinese NiTi wire was compared with Nitinol and stainless steel wires in a combined laboratory and clinical examination. In the laboratory test, the loading and unloading-deflection properties of the wires were determined in a three-point bending test and their surface properties were studied in a scanning electron microscope. This test attempts to simulate a common clinical situation. The NiTi material showed a non-linear force-deflection relationship. The increase in force from 1 mm deflection and onwards was very slow and the force delivered during unloading from large deflections was almost constant. This behaviour was somewhat different for smaller downward deflections of NiTi wires. Plastic deformation was insignificant. The clinical study confirmed the laboratory results obtained, characterizing a wire material much superior to stainless steel and even superior to Nitinol for alignment purposes. In clinical use, however, the rate of fractures of NiTi wires turned out to be unsatisfactorily high. This disadvantage was not predicted by the three-point bending test. Scanning electron microscopy revealed surface defects and non-metallic inclusions in fractured NiTi wires. A combination of a bending test simulating a clinical situation and surface examination is recommended when new wire materials are to be tested.

In an attempt to study the effect of osseointegrated implants on vertical dentoalveolar development, six growing pigs of the Pigham strain were used, one of them randomly selected as a control. The test pigs received four fixtures each, three in the lower jaw and one in the upper. The fixtures were placed in areas where different patterns of the dento-alveolar development were expected. The clinical and radiographic findings have clearly shown that the implants do not behave like normal erupting teeth during the development of the dentition. Neither do the fixtures move together with the adjacent teeth, but behave more like ankylosed teeth.

Two-hundred-and-thirty-eight subjects in three different age-groups (7, 11, and 15 years) were followed over a period of 4-5 years in respect of morphological malocclusions, and signs and symptoms of functional disturbances. About half of the 7-year-olds had at least one of the morphological malocclusions registered while the corresponding figure was 38 per cent at the age of 20. Some subjects had received corrective orthodontic treatment. When compared with subjects without such treatment, there were no differences in prevalences of occlusal interferences, nor in signs or symptoms of craniomandibular disorders (CMD). The associations between CMD and different morphological malocclusions were low. Nevertheless, some malocclusions were found to be more important than others. In a long-term perspective cross-bite, both uni- and bilateral, anterior open bite, post-, and prenormal occlusion had some association with the development of CMD.

The aim of this study was to examine the effects of repelling magnets on the treatment of anterior open bite and compare them with the effects of acrylic posterior bite-blocks. Twenty patients, aged 9-16 years with skeletal anterior open bite, were randomly divided into two groups. In one group the patients wore posterior repelling magnet splints and in the other they wore acrylic posterior bite-blocks of the same thickness as the magnet splints. The patients were instructed to use their appliance as much as possible (the minimum accepted being 18 hours daily) during a 6-month period. Dental casts, intra-oral photos, and lateral cephalograms were taken before and after treatment, and the patients were also examined regularly to identify the development of any craniomandibular disorders. In the first group, the dental and skeletal vertical relation responded quickly to the magnet treatment. The open bite was generally closed in just under 4 months, especially in patients in early mixed dentition. Spacing in the labial segments decreased in some cases, while slight crowding was induced in others. Transverse problems, i.e. unilateral cross-bite, sometimes followed by scissor-bite on the opposite side, was observed in those patients who were in the early mixed dentition and had used the magnets intensively. The patients who wore acrylic posterior bite-blocks also showed improvement in the dental and skeletal vertical relationships, especially during the first months. This was followed by a 'plateau' period. No transverse problems were found in these patients.

This follow-up study on transalveolar transplantation includes 56 maxillary impacted canines in 47 patients, with a post-operative control period of 2-10 years (mean 4.7 years). The prognosis of the transplanted teeth is still very good; only two canines have been lost, due to poor oral hygiene or fracture of the tooth. These positive follow-up results indicate that transalveolar transplantation will offer greater flexibility in the treatment of impacted maxillary canines in adults.

The occlusal traits and the craniofacial morphology were studied in patients with an altered muscle function caused by myotonic dystrophy. Twenty-four adult patients were examined and compared with a matched group of healthy individuals. The condition of the masticatory muscles was evaluated by measuring the maximal bite force. The dental arches and the occlusal traits were analysed on dental casts. Lateral cephalograms were taken in the patients with myotonic dystrophy to study the craniofacial morphology. It was found that the patients suffering from myotonic dystrophy had weak masticatory muscles, which might be caused by the disease. A high prevalence of malocclusions (postnormal occlusion, anterior open bite and lateral cross bite) was found among these patients. Their craniofacial morphology showed a vertical aberration, characterized by a large angle between the mandibular and palatal planes and a steep mandible. These findings seem to be most pronounced in patients with an early onset of the disease and support the hypothesis that reduced muscle function may cause changes in the craniofacial morphology.

The wide therapeutic use of hormones enhances the importance of detailed knowledge of the effects on skull growth. Thyroxine is known to regulate maturation of cell populations and long bone growth, but the influence on craniofacial bone remodelling is still obscure. One side effect of substitution therapy with thyroxine in children is premature closure of cranial sutures. The aim of the present study was to describe longitudinally the effect of different serum levels of thyroxine on craniofacial growth. In young rats injected with 20 micrograms/kg b.w. l-thyroxine for 28 days a change was found in craniofacial morphology measured by a cephalometric technique. A decrease in length of the viscerocranium was evident after 14 days, and occurred in connection with raised serum levels of thyroxine. In contrast, cranial base growth was increased between day 14 and 28 and also a catch-up growth in the viscerocranium was observed during this period. This observed change occurred after the induced peak in levels of thyroxine in serum had subsided. The inhibited forward directed growth of the viscerocranium was consistent with the fact that the skull in the thyroxine group developed a klinorhycial form in contrast to the normal orthocranialization. Thus, the craniofacial growth pattern was influenced by variations in the serum level of thyroxine. The effects of thyroxine on skull growth sites observed are consistent with reported effects of low dose of thyroxine on long bone growth.