Craniofacial growth disturbance is related to temporomandibular joint abnormality in patients with juvenile idiopathic arthritis, but normal facial profile was also found at the 27-year follow-up.

OBJECTIVES: To assess the long-term outcome of craniofacial morphology related to disease variables and temporomandibular joint (TMJ) involvement as demonstrated with computed tomography (CT) and magnetic resonance imaging (MRI) in adult patients with juvenile idiopathic arthritis (JIA). METHODS: Sixty of 103 patients participated in a re-examination on average 27 years after baseline. Craniofacial morphology, with emphasis on size and position of the mandible, was assessed in lateral cephalographic images and related to disease variables and TMJ involvement by CT and MRI. Definitions of craniofacial growth disturbances were based on measurements outside 2 SD from the mean of healthy adult controls. RESULTS: Sagittal craniofacial growth disturbances were found in 57% and micrognathia in 27% of the 60 patients. Of those with JIA TMJ involvement, 70% had some form of growth disturbance. Micrognathia occurred only in patients with bilateral TMJ involvement. The bilateral TMJ group had significantly different craniofacial morphology than healthy controls and patients without TMJ involvement. Growth disturbances and TMJ involvement were present in all subtypes of JIA, except for one subtype comprising one patient. Patients with growth disturbances had more severe disease than patients with normal craniofacial growth, regarding both present and previous disease activity. Unexpectedly, half of the patients without craniofacial growth disturbances also had TMJ involvement, many from before the age of 12. CONCLUSIONS: Craniofacial growth disturbances were found to be frequent in adult JIA patients, especially in those with bilateral TMJ involvement. However, growth disturbances did not always follow TMJ involvement, not even when affected early.

Relationship between disease course in the temporomandibular joints and mandibular growth rotation in patients with juvenile idiopathic arthritis followed from childhood to adulthood.

OBJECTIVE: To investigate the relationship between radiographic JIA disease course in the TMJs and mandibular growth rotation, compared with growth in healthy individuals. METHODS: From a larger series of JIA patients followed from childhood to adulthood, 26 were included; 11 without and 15 with bilateral radiographic TMJ involvement. Joint morphology and function were assessed at baseline, 2-, 4-, 6- and 27 years follow-up. Mandibular growth rotation (anterior, posterior or none) was assessed from cephalometric evaluations at childhood and adulthood, with observations from 16 healthy individuals as controls. TMJ disease course and mandibular growth rotation were assessed independently and their relationship analysed. Non-parametric statistical methods were applied to test differences between groups. RESULTS: In the normal TMJ group of JIA patients the joint morphology was similar at the follow-ups and all patients had good function both in childhood and in adulthood. The mandibular growth rotation was similar to that of healthy controls, i.e. predominantly in anterior direction. In the abnormal TMJ group different JIA TMJ disease courses were observed and associated with changes in the mandibular growth rotation (p = 0.007).Progressing JIA TMJ disease course was related to posterior mandibular growth rotation and improving disease course to anterior mandibular growth rotation. CONCLUSION: A relationship was found between JIA disease course in the TMJs and mandibular growth rotation, suggesting that a favourable growth could be regained in patients with improvement in TMJ morphology and/or TMJ function. To confirm this, further research on larger patient series is needed.

The protective effect of TiF4, SnF2 and NaF on erosion of enamel by hydrochloric acid in vitro measured by white light interferometry.

The purpose of this in vitro study was to compare the protective effect of TiF4, SnF2 and NaF (all 0.5 M F) on the development of erosion-like lesions in human dental enamel. Four enamel specimens from each of 6 extracted molars were polished and embedded in epoxy resin. The enamel surfaces of 3 specimens from each tooth were treated with the different fluoride solutions for 2 min. Following fluoride treatments, the specimens were immersed in 0.01 M HCl (pH 2.0), for 2, 4 and 6 min in order to mimic a gastric reflux situation. One specimen from each tooth was used as a control and was only exposed to acid. The etching depths (in micrometres) after 6 min were: TiF4 0.8 (SD 0.8), SnF2 3.5 (SD 0.7), NaF 5.3 (SD 0.4), and 7.0 (SD 0.3) for the control specimens. Compared to the control, TiF(4) protected the enamel surface from acid attack almost completely (88%), while SnF2 reduced the etch depth after 6 min by 50% and NaF by 25%.

A prospective, randomized clinical study on the effects of an amine fluoride/stannous fluoride toothpaste/mouthrinse on plaque, gingivitis and initial caries lesion development in orthodontic patients.

The aim of this study was to examine the effect of combined use of a toothpaste/mouthrinse containing amine fluoride/stannous fluoride (AmF/SnF2; meridol) on the development of white spot lesions, plaque, and gingivitis on maxillary anterior teeth in orthodontic patients. A prospective, randomized, double-blind study with 115 orthodontic patients (42 males and 73 females, average age 14.4 years, drop outs 18) was designed. Group A (50) brushed twice daily with an AmF/SnF2 toothpaste (1400 ppm F) and rinsed every evening with an AmF/SnF2 solution (250 ppm F). Group B (47) brushed twice daily with a sodium fluoride (NaF) toothpaste (1400 ppm F) and rinsed every evening with a NaF solution (250 ppm F). Visible plaque index (VPI), gingival bleeding index (GBI) and white spot lesion index (WSL) were recorded on the six maxillary anterior teeth at bonding and after debonding, and evaluated with t tests. In group A no significant differences between bonding and debonding were recorded for WSL (1.02 +/- 0.08 versus 1.05 +/- 0.13, P = 0.14), VPI (0.10 +/- 0.21 versus 0.12 +/- 0.21, P = 0.66) or GBI (0.13 +/- 0.21 versus 0.16 +/- 0.22, P = 0.47), whereas statistically significant differences were found in group B between bonding and debonding for WSL (1.00 +/- 0.02 versus 1.08 +/- 0.17, P = 0.01), VPI (0.06 +/- 0.13 versus 0.17 +/- 0.25, P = 0.01) and GBI (0.06 +/- 0.12 versus 0.16 +/- 0.21, P = 0.01). The increase in lesions on the upper anterior teeth was 4.3 per cent in group A and 7.2 per cent in group B. It was concluded that the combined use of an AmF/SnF2 toothpaste/mouthrinse had a slightly more inhibitory effect on white spot lesion development, plaque and gingivitis on maxillary anterior teeth during fixed orthodontic treatment compared with NaF.

Transversal dental arch dimensions in 9-year-old children born in the 1960s and the 1980s.

The transversal arch dimension has been studied in 2 different cohorts of 9-year-old children, a group of 119 (56 girls and 63 boys) from Norway and a group of 133 (72 girls and 61 boys) from Sweden. Half of the children in each group were born in the 1960s and half in the 1980s. The maxillary and mandibular transversal dimensions did not differ between the 1960s groups and the 1980s groups when the maxilla and the mandible were studied separately. When the intermaxillary relationship was assessed, a significant reduction in the intermaxillary difference was found in the boys born in the 1980s compared with the boys born in the 1960s. This was confirmed with different measurement points. In the girls, the mesial drift of the first permanent molars, because of a greater prevalence of caries in the 1960s groups, masked this effect. When the mesial drift of the first permanent molars in the girls born in the 1960s was considered, the transversal intermaxillary difference showed the same secular pattern as in the boys. When the mesial drift of the first permanent molars was considered, the intermaxillary difference in the 1960s groups resembled that found in an American sample of northwest European ancestry born in the 1940s to a greater extent compared with the children born in the 1980s.

Effects of combined application of antimicrobial and fluoride varnishes in orthodontic patients.

A randomized prospective clinical study, with 220 patients scheduled for fixed orthodontic therapy, was conducted to test the hypothesis that application of an antimicrobial varnish in combination with a fluoride varnish (group 1) is significantly more efficient in reducing white spot lesions on the labial surfaces than application of the fluoride varnish alone (group 2). The effects of the antimicrobial varnish on the occurrence of gingivitis and plaque formation were also studied. A third aim was to investigate whether white spot lesion development could be predicted early during treatment. The antimicrobial varnish significantly reduced the number of mutans streptococci in plaque during the first 48 weeks of treatment. This effect did not result in significantly less development of white spot lesions on the labial surfaces compared with the group receiving only the fluoride varnish application. There was however a clear trend that the combination of the antimicrobial and fluoride varnishes more effectively reduced the increments of new lesions on the maxillary incisors. It was speculated that this could be due partly to an inhibiting effect of the antimicrobial varnish in an area with low oral clearance (with low pH and loss of fluoride) and partly to an inhibiting effect of the varnish on mutans streptococci. No significant differences between the groups with respect to gingivitis and plaque were found. Lesion development was difficult to predict early after bonding, despite a number of caries-relevant parameters of orthodontic importance. The best predictors for white spot lesions at debonding were visible plaque and mutans streptococci (eg, the level of oral hygiene and thus the cariogenic challenge) around the appliance shortly after bonding.

CaF(2) formation: cariostatic properties and factors of enhancing the effect.

CaF(2) or a CaF(2)-like material/phosphate-contaminated CaF(2) is a major reaction product during topical treatment of dental hard tissues. Recently, evidence has suggested that CaF(2) is formed not only on surfaces but also to some extent in the enamel. The minimum concentration of fluoride required for CaF(2) formation is not well known and may depend on whether calcium is available from plaque fluid or only through dissolution of the dental hard tissue. Furthermore, surface adsorption of fluoride to crystals may cause local concentrations necessary for CaF(2) formation. It has been suggested that CaF(2) acts as a pH-controlled reservoir of fluoride. The rate-controlling factor appears to be phosphate, which controls the dissolution rate of CaF(2) at high pH. Increasing fluoride concentration, prolonging the exposure time or using a fluoride solution with low pH can increase CaF(2) formation. CaF(2) formed at low pH contains less internal phosphate which has been shown to be less soluble. This may be of clinical significance for fluoride applied topically a few times per year.

Anterior space relations and lower incisor alignment in 9-year-old children born in the 1960s and 1980s.

The anterior arch spaces and the effect of early loss of deciduous canines have been studied in 2 different cohorts of 9-year-old children. One group of 119 children was from Norway and consisted of 56 girls and 63 boys, and 1 group of 133 children was from Sweden and consisted of 72 girls and 61 boys. Within these cohorts, half of the children were born in the 1960s and half in the 1980s. The 1960s group has been compared with the 1980s group to look for anterior arch changes occurring during this period of time. The children who had lost a lost deciduous canine at the age of 9 years were also compared with the children with all deciduous canines remaining. Groups were compared with analysis of variance. It was found that children with a lost deciduous canine at the age of 9 years belong to a group with less available arch space and are a crowded group when compared with an earlier study. For the girls, this was also associated with larger teeth. Anterior arch space did not differ between the 1960s and the 1980s groups except for the Swedish boys, where there was less available mandibular arch space in the 1980s group. The irregularity index for the 4 mandibular incisors was increased in the 1980s group compared with the 1960s group. This could indicate a secular trend toward an increased prevalence of malocclusion in the present population.

Difference in dental lateral arch length between 9-year-olds born in the 1960s and the 1980s.

This study was carried out in two cohorts of 9-year-olds, born in the 1960s and the 1980s in Sweden and Norway, to test the hypothesis that there has been a change in the lateral arch space conditions of the dentition during the last decades. In Norway, 61 children born in 1963 and 58 children born in 1983 were examined. In Sweden, 66 children born in 1961 and 67 children born in 1984 were examined. Children with a prolonged sucking habit, major dentofacial anomalies, history of orthodontic treatment, and ancestors of foreign origin were excluded to avoid influence of these factors on the development of the dentition. Linear measurements were performed between the mesial surface of the first permanent molars and the distal surface of the permanent lateral incisors in the maxillary and mandibular dental arches with use of a sliding caliper. The results showed that the children born in the 1980s had significantly larger lateral arch spaces in the maxillary dental arch (P <.05) and in the mandibular dental arch (P <.01) than did the children born in the 1960s. The amount of tissue loss in the second deciduous molars (the teeth having caries lesions or having been extracted) was greater in the 1960s groups than in the 1980s groups (P <.001). Thus, the hypothesis, that there has been a change in the lateral arch space conditions during the last decades, was confirmed. The most obvious reason is the decline in caries prevalence that has occurred in the same period; thus, there has been less loss of proximal tooth material of posterior teeth.

The effect of long-term water storage on the tensile strength of orthodontic brackets bonded with resin-reinforced glass-ionomer cements.

The purpose of this study was to evaluate in vitro the effect of water storage on the tensile bond strength of orthodontic brackets bonded with Vitremer and Fuji II LC resin-reinforced glass-ionomer cements. Seventy-two extracted human premolars were randomly divided into 6 groups and the bonding strengths of the resin-reinforced glass-ionomer cements were compared to control groups bonded with Concise composite resin at 24 hours and 9 months. The brackets were bonded on prepared teeth and a tensile load was applied to dislodge the brackets held in a special device from Lloyd 1000R testing machine. The effects of duration of water exposure, type of bonding material and interaction between long-term water exposure and type of bonding material on the bonding strength were described using the Weibull regression model. The mean tensile bond strength of resin-reinforced glass-ionomers after 24 hours water storage was significantly lower than the mean of the control samples. The results of this study showed no effect of water exposure on the tensile bond strength of brackets bonded with Vitremer glass-ionomer cement. The mean bonding strength of brackets bonded with Fuji II LC without enamel pre-conditioning significantly increased after 9-months water storage as compared to Fuji samples exposed to water for 24 hours. The results of this investigation allow to conclude: 1. Long-term water storage had not decreased the bond strength of resin-reinforced glass-ionomers applied as orthodontic adhesives, 2. Weibull regression model is an adequate and flexible tool to evaluate the bonding properties of dental materials.

The cariostatic mechanism of fluoride.

The benefits of using fluoride to prevent caries have been known for many years, but a complete understanding of this mechanism is still being researched. The fluoride concentration in the apatitic structure of enamel does not have as significant an effect on reducing caries as a continuous presence of fluoride in the plaque liquid. Concentrated, topical fluoride agents (such as in toothpaste, fluoride mouth rinses, gels, or varnishes) have a different mechanism of fluoride protection than low-concentration applications (such as fluoridated water). In initial caries lesions and plaque, concentrated agents form globules of a calcium fluoride-like material on the enamel surface. This material is fairly insoluble, possibly because it is coated with phosphates or proteins. This mechanism explains how the topical application of a fluoride varnish, two or three times a year, can result in caries reduction.

Experimental intra-oral caries models in fluoride research.

The use of experimental intra-oral caries models has increased in fluoride research. This paper focuses on the pre-clinical intra-oral models, the in situ and in vivo models, the various types, their benefits and disadvantages. Both preparation and sterilization of the hard tissue substrates can affect the substrates and therefore the results. Care needs to be taken that dentine samples are not exposed to drying and consequently shrinking during preparation and evaluation. Sterilization by gamma-radiation is at present the least tissue-damaging method. The most realistic experimental model is the in vivo model, followed by the in situ model using specimens with natural surfaces. The most accurate and direct evaluation technique for demineralization and remineralization studies is quantitative transversal microradiography, whereas confocal laser scanning microscopy (CLSM) is the most sensitive qualitative evaluation technique. Other evaluation techniques discussed are microhardness testing and the iodine permeability test. In light of the present skewed caries situation in western countries we suggest that fluoride research focuses on experimental caries models that can mimic severe cariogenic challenge. Testing of fluoride combinations and dosages that can prevent lesion development rather than promote remineralization would then be a practical consequence.

Pain and discomfort experienced after placement of a conventional or a superelastic NiTi aligning archwire. A randomized clinical trial.

Two nickel-titanium arch-wire types commonly used for initial tooth alignment were compared with regard to the pain/discomfort patients experience during the initial phase of tooth movement. The two arch wires used were a superelastic nickel-titanium alloy, 0.014 inch Sentalloy, Light (GAC International Inc. Central Islip, NY, USA) and a 0.014 inch Nitinol (Unitek, Monrovia, CA, USA), a conventional nickel-titanium aligning archwire. One hundred and twenty-eight consecutive patients attending an orthodontic university clinic and 2 private practices for routine placement of a fixed appliance were randomly assigned one of these 2 initial arch wires. Assessments of pain/discomfort were made daily by means of a 100 mm visual analog scale (VAS) over the first 7-day period after bonding. On the first day, recordings were made every hour for the first 11 hours. The results showed that the level of discomfort increased continuously every hour after the insertion of either a Sentalloy or a Nitinol as first arch wires, with a peak in the first night, remaining high on the second day and decreasing thereafter to baseline level after 7 days. During the first 10 hours it was apparent that the pain/discomfort experienced after placement of a Sentalloy was less than that found with the Nitinol archwire, although a significant difference could be found at 4 hours only. No significant gender-specific differences were found in either archwire group. A significant difference between the upper and lower dental arches was observed during the first 11 hours after placement of either a Sentalloy or a Nitinol arch wire, with the lower arch having the higher pain experience.

Cariostatic effect of a light-cured, resin-reinforced glass-ionomer for bonding orthodontic brackets in vivo. A combined study using microradiography and confocal laser scanning microscopy.

The aim of this study was to evaluate in vivo the cariostatic potential of the resin-reinforced glass-ionomer (Vitremer core build-up restorative; 3M Dental Product Division) when used as a bonding agent for orthodontic brackets. The mineral distribution and topography of the enamel surface adjacent to the bracket base was determined by quantitative microradiography (TMR) and confocal laser scanning microscopy (CLSM). The study was designed in split-mouth technique using 9 pairs of premolars to be extracted for orthodontic reasons. One tooth of each pair was bonded with the resin-reinforced glass-ionomer, and the control contralateral premolar with the non-fluoridated composite (Concise, 3M Dental Products Division). After 4 weeks all teeth were extracted and stored until analysis. The lesion depths and mineral loss values in enamel adjacent to brackets bonded with Vitremer were significantly lower than in teeth bonded with the composite, indicating that the resin-reinforced glass-ionomers significantly reduced caries lesion development in vivo. CLSM images show a severe cariogenic challenge around orthodontic brackets and support TMR measurements.

Fluoride-induced precipitates on enamel surface and subsurface areas visualised by electron microscopy and confocal laser scanning microscopy.

The present study examined the enamel surface after in vitro topical treatments with a neutral 2% NaF solution. For minimising the risk of artefacts, samples were inspected without pre-treatment as fresh, naturally wet specimens by complementary techniques: variable pressure electron microscopy (VP-SEM) and confocal laser scanning microscopy (CLSM). VP-SEM provided information on the surface morphology, whereas CLSM allowed non-destructive visualisation of subsurface areas. Neutral NaF solutions induced globular precipitates on the enamel surfaces. If the globules formed may be described as "calcium fluoride like material", the additional information of this experiment is that, after interaction with neutral solutions, they also contain considerable amounts of NaF. When the NaF solutions were soaked on pellets and then were brought into contact with the enamel surfaces, NaF crystallites of cubic shape are formed. Confocal optical tomographies of subsurface enamel after treatments with neutral NaF solutions revealed partly coroded enamel structures, whereas VP-SEM showed intact surfaces. In between the coroded areas, a fine granulate precipitate could be observed. This is evidence that fluoride induces the formation of sub-surface precipitates only when applied during demineralisation. The precipitate could be readily removed by 24-h contact with a KOH solution.

The resistance of titanium tetrafluoride-treated human enamel to strong hydrochloric acid.

The acid resistance of TiF4-treated enamel was investigated to establish a possible treatment modality for endogenous dental erosion. Enamel slabs were prepared from human molars and treated with solutions of TiF4. Scanning electron microscopy (SEM) and microhardness testing were used to examine the effects of the exposure of the treated enamel to strong acid. SEM micrographs showed the presence of heavy deposits on enamel surfaces. The surface coating, formed following TiF4 application, appeared to be resistant to severe acid attacks. Microhardness measurements showed that TiF4 treatment inhibited enamel softening. It is concluded that topical TiF4 application may be effective in prevention of dental erosion caused by hydrochloric acid from the stomach in patients with frequent vomiting or gastroesophageal reflux.

The need and demand for orthodontic treatment in 13- to 15-year-olds in Nairobi, Kenya.

The need for orthodontic treatment in Kenya was previously not been investigated. This study was undertaken to assess the need for orthodontic treatment in 13- to 15-year-old children in Nairobi. The objective need was assessed in 919 children by using the Norwegian treatment need index, and the subjective need was assessed in 739 children by using a structured questionnaire. Objective treatment need was recorded in 29% and subjective need in 33% of the children. Less than 1% were allocated the 'very great need' category. Relatively more girls than boys were dissatisfied with the appearance of their teeth, and a significantly higher number of girls (P < 0.001) said they would like to have their teeth straightened. The children's perceived need for treatment correlated significantly with the treatment need index. Fixed appliances were found necessary for correcting malocclusion in 23% of the children and removable appliances in 6%. Future studies in Kenya should be directed at determining the societal perception of malocclusion, upon which treatment standards may be based.

Retention of titanium tetrafluoride (TiF4), used as fissure sealant on human deciduous molars.

When dental hard tissues are exposed to aqueous solutions of TiF4, an acid-resistant glaze forms on tooth surfaces. The aim of the present study was to examine the long-term retention of the glaze on TiF4-treated deciduous molars. The occlusal surfaces of four deciduous molars in each of seven children were treated with 4% TiF4 for 1 min. The sealed teeth were extracted after 1, 3, 6, or 12 months and examined with scanning electron microscopy. An extensive surface layer was present on all deciduous molars after 1 month. After 3 months the glaze appeared to be worn out on the cusp tips and in some areas on the cusp inclines. At 6 months the glaze was observed as small areas distributed over the cusp inclines with total coverage of the pits and fissures. After 1 year the presence of the glaze was limited to pits and fissures. Clinically, all fissures were caries-free by visual inspection at the end of the experimental period. The results indicate that the glaze formed after topical TiF4 application may be an effective way of sealing pits and fissures under clinical conditions.

Fluoride level in saliva after bonding orthodontic brackets with a fluoride containing adhesive.

The fluoride level in saliva is considered an important parameter in caries prevention. Elevation of the salivary fluoride level by a fluoride-releasing orthodontic bonding adhesive would most likely be beneficial in the prevention of enamel caries. In this study, the fluoride level in saliva was measured after bonding brackets with a visible light-curing adhesive containing fluoride (12.4 wt% total F). The fluoride released from the adhesive has been shown in a previous study to inhibit demineralization adjacent to orthodontic brackets in vivo. Twenty-four patients each had 20 brackets bonded and saliva samples taken before bonding (t = 0) and after 1, 3, and 6 months. The participants were requested to brush daily with a fluoride toothpaste during the study period. The saliva fluoride analysis was done with the microdiffusion method. The analysis of the saliva showed fluoride levels (+/- SD) of 0.011 +/- 0.007, 0.011 +/- 0.009, 0.0011 +/- 0.007, and 0.012 +/- 0.008 ppm at t = 0, 1, 3, and 6 months, respectively. There was no significant difference at the 5% level. The study indicated indirectly that the caries inhibiting effect of the orthodontic adhesive shown previously was most likely due to a localized fluoridation of the cariogenic environment rather than to an elevation of the fluoride level in saliva.

Antimicrobial effect of a chlorhexidine-thymol varnish (Cervitec) in orthodontic patients. A prospective, randomized clinical trial.

The aim of the present investigation was to study the effect of combined application of a fluoride varnish (Fluor Protector) and an antimicrobial varnish (Cervitec) on the oral microflora, caries and gingival condition in patients receiving treatment with fixed orthodontic appliances. A total of 198 individuals (12 to 15 years old), scheduled for fixed orthodontic treatment, were randomized into 2 groups. Prior to bonding, the Cervitec and the control group received one application with Cervitec or a placebo every week for 3 weeks, respectively. In the Cervitec group. Fluor Protector was applied at bonding and Cervitec at the next visit, 6 weeks later. Each varnish was then applied every 12 weeks for 24 weeks. In the control group, the fluoride varnish was applied only at bonding and every 12 weeks. The Visible Plaque Index (VPI), the Gingival Bleeding Index (GBI), the White Spot Lesion Index (WSL) and the level of mutans streptococci in plaque and saliva were recorded 3 weeks prior to bonding and after 24 weeks. At bonding and after 12 weeks, only VPI, GPI, plaque and salivary mutans streptococcus counts were recorded. During the 3-week prebonding period, the mean VPI, GBI and mutans streptococci in plaque decreased in both groups. At bonding, the mean level of mutans streptococci in plaque was significantly lower in the Cervitec group than in the control group. The mean level of mutans streptococci was significantly lower after 12 weeks' bonding in the Cervitec group than in the control group. No effects on the other parameters were found during the 24 weeks.