Steven P. Jones

Psychosocial impact of hypodontia in children

INTRODUCTION The purpose of this cross-sectional study was to determine the psychosocial impact of hypodontia (multiple dental agenesis) in children and the influence of factors such as severity of hypodontia, number of retained deciduous teeth, age, and sex. The implications of hypodontia for affected patients have been poorly investigated; this, in part, relates to the lack of appropriate measurements to assess the impact of oral conditions on quality of life, particularly among children and adolescents. METHODS A total of 123 children (49.6% boys, 50.4% girls; mean age, 13.6 years; SD, 1.6 years) were recruited on the basis of predetermined inclusion criteria to either a hypodontia group or a routine orthodontic group of similar treatment need (index of orthodontic treatment need, dental health component 4 or 5) but without hypodontia. Each patient completed the child perceptions questionnaire and 2 visual analog scales to determine the global effects of hypodontia on esthetics and function. RESULTS The mean number of missing teeth in the hypodontia group was 4.52 (SD, 3.33). There were no statistically significant differences in child perceptions questionnaire scores (overall or at domain level) or visual analog scores between the hypodontia and the routine orthodontic groups (P >0.05). Univariable linear regression analyses provided some evidence that difficulty with chewing was associated with the severity of hypodontia (P = 0.030). CONCLUSIONS In this sample, hypodontia did not appear to affect the psychosocial status of patients any more than other features of a malocclusion measured with the index of orthodontic treatment need, dental health component 4 or 5. Patients with hypodontia did, however, have more difficulty in chewing when the deciduous teeth associated with the missing permanent teeth had been exfoliated. This highlights the possible importance of retaining deciduous teeth in patients with severe hypodontia.

Radiographic study of delayed tooth development in patients with dental agenesis

INTRODUCTION The aims of this study were to compare the radiographic development of permanent teeth in a group of children affected by dental agenesis with an unaffected control group and to determine the effects of confounding factors including the severity of the dental agenesis, age, sex, ethnicity, and the number of stages used to estimate dental age. METHODS A single-center retrospective cross-sectional study of dental panoramic tomographs was undertaken between July 2007 and April 2008 in a postgraduate teaching school. A total of 139 patients (aged 9-18 years) were recruited from the orthodontic clinic on the basis of predetermined inclusion and exclusion criteria to either a dental agenesis group or a control group. Dental panoramic tomograms were assessed, and the stages of development of the permanent teeth in the left maxillary and left mandibular regions were scored by using the 12 stages of Haavikko and the 8 stages of Demirjian and Goldstein. For each tooth scored, the mean dental age and standard error were determined by using the dental age assessment method, and an estimated dental age for each subject was derived by using the weighted average method. RESULTS A statistically significant delay in dental age was found in the patients with dental agenesis compared with the control group. The dental age assessment method of Haavikko showed a delay of 1.20 years (SD, 1.74), and the method of Demirjian and Goldstein showed a delay of 1.64 years (SD, 1.75). It was also observed that older patients with dental agenesis had greater delays in tooth formation (P <0.001). With the Haavikko method, for every year of chronologic age, the delay in dental age increased by 0.53 year; with the Demirjian and Goldstein method, the delay increased by 0.48 year. A significant association was seen between the severity of dental agenesis and the delay in dental age (P <0.01). With both methods, for each additional developmentally absent tooth, the dental age was delayed by 0.13 year (lower confidence interval, -0.22; upper confidence interval, 0.35). There was no evidence that sex or ethnicity has an effect on the delay in dental age in patients with dental agenesis. CONCLUSIONS The development of permanent teeth in children with dental agenesis is delayed when compared with a matched control group. The severity of dental agenesis affected the magnitude of the delay (P <0.01). This delay has implications in orthodontic treatment planning and in the estimation of age for legal, immigration, archaeological, and forensic purposes.

A cephalometric study to investigate the skeletal relationships in patients with increasing severity of hypodontia

OBJECTIVES To determine the skeletal relationships in patients with hypodontia and analyze the effects of severity and pattern. MATERIALS AND METHODS Pretreatment lateral cephalograms from 277 patients with hypodontia, categorized by the number of missing teeth as mild (1-2), moderate (3-5), or severe (> or =6), were digitized recording angular measurements and ratios and compared with published norms matched for age and gender. Pattern was determined as mandibular, maxillary, bimaxillary, bilateral, anterior, posterior, and anteroposterior. Linear regression models assessed relationships between number of missing teeth and cephalometric parameters, controlling for the pattern of hypodontia. RESULTS For every additional missing tooth, SNA, SNB, and ANB decreased 0.3 degrees , 0.1 degrees , and 0.2 degrees , respectively; this was clinically significant for >4, >10, and >5 missing teeth, respectively. Mandibular to cranial base ratio decreased 0.3% for every additional missing tooth; this was clinically significant for >10 missing teeth. The MMPA decreased 0.3 degrees for every additional missing tooth; this was clinically significant for >7 missing teeth. Percentage LAFH decreased 0.2% for every additional missing tooth; this was significant for >7 missing teeth. Jarabak ratio increased 0.2% for each additional missing tooth; this was clinically significant for >10 missing teeth. Anterior hypodontia significantly decreased most cephalometric parameters. CONCLUSIONS Patients with hypodontia demonstrated a tendency toward a Class III relationship, caused by decreased maxillary and mandibular angular prognathism and MnCB ratio, though the effect was greater on the maxilla than the mandible. Clinical significance was only associated with severe hypodontia. Vertically, there was a tendency toward decreased MMPA and %LAFH; this was clinically relevant only with severe hypodontia. Anterior hypodontia had a significant effect on skeletal relationship.

Advances in orthodontics.

There has been tremendous progress in orthodontics since Edward Angle first popularised the fixed orthodontic appliance at the turn of the century. Recent years have seen an increased demand for orthodontic treatment from both adolescents and adults and, in addition, patient and clinician expectations of treatment outcomes continue to rise. A desire for more aesthetic materials has resulted in both smaller and ‘tooth-coloured’ appliances. Improvements in technology, often outside orthodontics, have also led to the development of new materials. The best example of this was the development of nickel titanium alloy by the NASA space programme, which was subsequently adapted for use in nickel titanium archwires. Other technological advances adopted for use in orthodontics include magnets, computerised imaging systems and distraction osteogenesis. This review paper looks at some of the innovations in the fields of materials as well as in techniques and appliance systems.

A study to investigate the bond strengths of orthodontic brackets bonded to prosthetic acrylic teeth

Introduction In this study, we compared the shear bond strengths of five different adhesive techniques for attaching metal orthodontic brackets onto acrylic pontics. Materials and Methods Two hundred upper left lateral incisor acrylic teeth with bonded brackets were divided into five groups — composite alone (control), composite following sandblasting, composite held with a mechanical undercut, cyanoacrylate adhesive and Panavia®. The initial bond strength was tested using the Instron Universal Testing Machine. The fatigue bond strength was tested by subjecting each bracket to 5000 repetitive low-load cycles at 50% of the mean shear bond strength using the Dartec machine at 2 Hz. Results Cyanoacrylate adhesive statistically exhibited the highest mean bond strength (19·82 MPa). This was followed by the mechanical undercut group (17·69 MPa) and the sandblasted group (17·18 MPa). There was no statistically significant difference when considering the effect of fatiguing (p = 0·238) as well as the interaction between the adhesive technique and the effect of fatiguing on the bond strength (p = 0·440). Conclusion The initial and fatigue bond strengths of the cyanoacrylate adhesive, sandblasted and undercut groups were significantly higher than the control and Panavia® groups when tested under laboratory conditions.

Initial and fatigue bond strengths of nanofilled and conventional composite bonding adhesives

Aim To compare the initial and fatigue shear bond strengths of a nanofilled adhesive with a conventional light-cured adhesive in an ex vivo laboratory study. Methods Fifty hydroxyapatite discs were prepared by cold pressing. Using a standardized bonding protocol, 100 Victory series upper left central incisor brackets were bonded to discs with Transbond™ Supreme LV nanofilled composite resin and 100 brackets were bonded to discs with Transbond XT. Fifty brackets from each group were subjected to cyclic loading (5000 cycles at 2 Hz) at 50% of the mean bond strength in a Dartec Series HC10 Testing Machine. Initial (unfatigued) and fatigued bond strengths were determined by applying a shear force at the bracket/substrate interface using a custom-made metal jig in an Instron Universal Testing Machine. Results and statistical analysis One-way analysis of variance showed that Transbond Supreme LV exhibited higher initial mean bond strength than Transbond XT (P = 0·001). No statistically significant difference was found between the fatigue bond strengths of Transbond Supreme LV and Transbond XT (P = 0·323). Two-way analysis of variance demonstrated statistically significant differences when the effect of the composite resin (P = 0·013) and fatigue (P = 0·017) were considered individually. However, when considered in combination there was no statistical significance (P = 0·09). Kaplan–Meier survival analysis showed superior survival of unfatigued brackets with Transbond Supreme LV, but there was no significant difference between the adhesives after fatiguing. Conclusions The initial bond strength of Transbond Supreme LV was significantly higher than Transbond XT, while the fatigue bond strengths of both resins were comparable. Overall, Transbond Supreme LV demonstrated superior survival under loading than Transbond XT. However, while this was statistically significant for the initial loading, it was not significant after fatiguing. Although these laboratory findings are useful as indicators of potential clinical performance, extrapolation of these results should be carried out with caution.

The relationship between base dimensions, force to failure, and shear bond strengths of bondable molar tubes.

OBJECTIVES To compare forces versus failure and shear bond strengths, and to explore their association with the base dimensions of four currently available bondable molar tubes. MATERIALS AND METHODS Tubes were bonded to hydroxyapatite discs using a conventional light-cured adhesive and were tested to shear failure with the Instron Universal testing machine. Results were analyzed using the Kruskal-Wallis test and regression and survival analyses. RESULTS No statistical difference was observed between the four groups globally in terms of force to failure (P  =  .059) and bond strength (P  =  .179). However, regression analysis showed that each 1 mm(2) increase in base surface area required an additional force of 3.11 N to debond the tube. Survival analysis showed that the tube with the greatest base dimensions had the best survival with increasing force to failure. CONCLUSIONS Although a relationship was demonstrated between force to failure and base surface area, it was not a simple one. No statistically significant relationship was found between bond strength and base surface area.

Improving occlusion and orofacial aesthetics: orthodontics

Malocclusion is the abnormal positioning of the teeth or jaws. It is a variation of growth and development and can affect a persons bite (occlusion), ability to clean teeth properly, gingival health, jaw growth, speech development, and appearance. Patient with crowded teeth and malocclusion (top) and after orthodontic treatment (bottom) The shape and size of the face, jaws, and teeth are mainly inherited, but environmental factors can also have an impact. Factors as diverse as skeletal muscle pathology1 and sucking a digit (thumb or finger) can substantially influence the growth of the face and dentition. Treatment of disorders such as crowded or protruding teeth may improve both aesthetics and oral function. In addition, prominent teeth can be damaged easily during childhood. The dental specialty most concerned with problems of facial growth, development of occlusion, and the prevention and correction of associated anomalies is orthodontics. The improvement of occlusion and aesthetics using restorative dental techniques is discussed in the next article. The demand for orthodontic treatment is increasing to such an extent that an objective index of orthodontic treatment need (IOTN) has been established to ensure that resources are directed to patients with the greatest clinical need and who are likely to benefit most.2 3 #### Prevention or treatment of malocclusion may help Apart from a thorough history and examination, photographs of the face and teeth and models of the teeth are used to provide a record and facilitate treatment planning. Several types of radiograph may also be needed. Most commonly used are panoramic radiographs, which show all the upper and lower teeth in biting position as well as any teeth still developing within the jaws, and a lateral cephalometric radiograph, which shows the relation of the teeth and jaws to the face and base of the skull. ### Treatment #### Tooth extraction Carefully …

A comparison of skeletal maturation in patients with tooth agenesis and unaffected controls assessed by the cervical vertebral maturation (CVM) index

Objective The aims of this study were to (1) investigate if there is a difference in skeletal maturation between tooth agenesis and control patients and (2) whether skeletal maturation is affected by the severity of tooth agenesis. The cervical vertebral maturation (CVM) index can be used to assess skeletal maturation. Design A retrospective cross-sectional study. Setting Eastman Dental Hospital, London, UK. Methods and materials A total of 360 cephalograms of patients aged 9–17 years (164 males and 196 females) allocated to four subgroups (mild, moderate and severe tooth agenesis patients, and controls) were assessed retrospectively. There were 90 patients in each of the four subgroups. The skeletal maturation of each subject was assessed both quantitatively and qualitatively using the CVM index. All patients in the study were either currently receiving treatment or had been discharged from the hospital. Results There was no statistically significant relationship between skeletal maturation and the presence of tooth agenesis. Furthermore, there was no statistically significant relationship between the skeletal maturity of patients and different severities of tooth agenesis. Conclusions The data obtained from this group of patients and using this measurement tool alone does not supply sufficient reason to reject the null hypothesis. However, it suggests that it is possible that no difference exists between the groups.