November - 2010

After application of dental sealant or composite resin, residual monomer layer should be removed with pumice on a cotton pellet

• Literature review of bisphenol A (BPA) and related compounds in dental materials noted that dental resins were “composed primarily of BPA derivatives rather than pure BPA.  These derivatives are liquid monomers that polymerize into a solid after either chemical or light curing.” 
• Salivary enzymatic hydrolysis of BPA derivatives in dental resins releases BPA with BPA “detectable in saliva for up to 3 hours after resin placement.”  It was however cautioned that “BPA exposure after sealant placement is most likely an acute event.  Presumably, at a certain time after application, the unpolymerized monomer is completely absorbed into saliva, posing little risk of chronic low-dose BPA exposure.” 
• “Dental products containing the bisphenol A derivative glycidyl dimethacrylate (bis-GMA) are less likely to be hydrolyzed to BPA and have less estrogenicity than those containing bisphenol A dimethacrylate (bis-DMA).”  It was noted that bis-GMA was the more common ingredient in most dental resins. 
• It was recommended that the oxygen inhibited layer of unpolymerized monomer following sealant/resin application should be removed to reduce the levels of available monomer.  Pumice on a cotton ball or in a rubber prophylaxis cup were found to be effective for doing so. 

       (Pediatrics 2010; 126:760-768)

October - 2010

Distal displacement of lower second premolar may be a risk indicator for a palatally displaced canine

• Cross-sectional study of prevalence in 2811 Italian children of distal displacement of lower second premolar and its association with other dental anomalies including palatal displacement of canines, aplasia of third molars, aplasia of contralateral lower second premolar, aplasia of maxillary lateral incisors, and microdontia of maxillary lateral incisors.  Distal displacement of lower second premolar was defined as the distal inclination of its tooth bud as seen on a panoramic radiograph with the long axis of the premolar bud intersecting the mesial border of the adjacent permanent first molar. 
• It was noted that during root formation, “the mandibular second premolar has an orientation in the alveolar bone that is almost perpendicular to the lower border of the mandible as traced on a panoramic x-ray, and almost parallel to the long axis of the first permanent molar.”  Premolars with distal displacement showed an angulation of about 57 degrees to the lower border of the mandible and about 38 degrees to the long axis of the adjacent permanent first molar.
• The authors found a significant relationship between distal displacement of lower second premolar and prevalence of palatally displaced canines.  There were also greater prevalence of aplasia of second premolars, aplasia of maxillary lateral incisors, and microdontia of maxillary lateral incisors in the group with distal displacement of premolars and palatally displaced canines.  It was therefore observed that “the concurrent presence of these dental anomalies adds to the accumulated evidence supporting a shared genetic mechanism for dental anomaly patterns.”  The authors concluded that distal displacement of lower second premolars can be a developmental risk indicator for palatally displaced canines.

        (Am Orthod Dentofacial Orthop 2010; 138:318-322)

September - 2010

Obesity is associated with early eruption of permanent teeth but not associated with caries experience in permanent teeth

• Four-year longitudinal study of 88 Mexican children with a mean age of 7 years at the time of commencement of the study.  Height, weight and dental caries experience were measured on an annual basis.  Dental caries experience was scored using the World Health Organization criteria and no radiographs were taken.  Individual height and weight assessments were classified using the Centers for Disease Control’s 2000 gender-specific standards including body mass index (BMI).  
• Children who were in the 85^th or higher BMI percentile increased from 30% at 7 years of age to 46% at 11 years of age.  Significant association was noted between BMI and the number of erupted permanent teeth after controlling for gender and age at baseline.  Both DMFS and DMFT increased from 7 to 11 years of age.  However, dmft showed a declining trend from 7 to 11 years of age.  “No association was detected between BMI and DMFS scores.” 
• The authors’ observed that “the tendency for accelerated tooth eruption in the high-BMI children should be taken into account in dental care, particularly in those children who require interceptive, early orthodontic treatment or orthopedic appliances, among other treatments impacted by tooth eruption.”
• Reviewer’s note: The lack of association between BMI and caries experience in the present study needs to be interpreted with caution since no radiographs were taken and therefore caries experience was likely underestimated. 

       (Act Odontol Scand 2010; 68:57-64)

August - 2010

Rapid palatal expansion increases the transverse dimension of the maxilla with the greatest increase in the mid-palatal suture

• The effect of rapid palatal expansion (RPE) on transverse dimensions in the maxilla was studied using cone-beam computed tomography in 24 8-to-13-year-old children.  “For each patient, a bonded Haas-type maxillary expander was cemented in place.  The design of the expander was full occlusal and palatal acrylic coverage.  The occlusal coverage included the deciduous canine (or the permanent canine if in the arch) through to the first molar.”   
• The authors reported that after expansion the greatest increase in transverse dimension occurred in the mid-palatal suture which opened in a parallel fashion and showed about one-half of the jackscrew expansion.  The authors “found that, after RPE, at the level of the first molar, the mean nasal cavity width increase was 2.73 mm, the mean basal bone width increase was 3.33 mm, and the mean suture opening was 4.33 mm.  This demonstrated that the expansion had a triangular pattern, with the greatest increase in the suture, followed by basal bone width and the nasal cavity width.”  There was also significant buccal tipping of both maxillary first molars. 

         (Am J Orthod Dentofacial Orthop 2010; 137:S79-85)

 

July - 2010

Maternal xylitol gum chewing reduces mutans streptococci colonization in infants

• Randomized controlled trial of 107 pregnant Japanese women with high counts of mutans streptococci.  In the experimental group, maternal chewing of xylitol gum started at the sixth month of pregnancy and ended when their infants were 9 months of age.  In the control group there was no gum chewing.  Salivary samples were collected from the infants at 6, 9, 12, 18, and 24 months of age. 
• Infants of mothers in the xylitol group were less likely to show mutans streptococci colonization than control group infants at and after 9 months of age.  Further, control group infants acquired mutans streptococci 9 months earlier than did infants whose mothers chewed xylitol gum.

         (J Dent Res 2010; 89:56-60)

 

June - 2010

Resin infiltration along with fluoride varnish may have the potential to manage primary molar interproximal lesions

• Clinical study (split-mouth design) to determine the efficacy of resin-infiltrated caries lesions.  Five-to-eight-year-old children in Greenland (n = 50) with two or more primary molar interproximal lesions (in enamel or outer dentin) detected in bitewing radiographs.  Based upon random allocation, one tooth in each child received only fluoride varnish application (control) while the other received resin infiltration followed by fluoride varnish application (experimental).
• Resin infiltration procedure was undertaken as follows.  The proximal surface was cleansed with floss and rubber dam was applied.  The adjacent tooth was protected with a plastic or metal strip.  The lesion was treated with 15% hydrochloric acid for 120 seconds followed by rinse and dry.  The surface was then dehydrated by two applications of 95% ethanol and air-dried.  Infiltrant resin was then applied to the lesion for 120 seconds and was light polymerized.  The resin was re-applied for 30 seconds and polymerized.  And then fluoride varnish was applied. 
• After one year, ICDAS scores showed progression in 31% of the lesions in the experimental group while 67% of the lesions in the control group had progressed.  Bitewing radiographs demonstrated progression in 23% of the lesions in the experimental group while 62% of the lesions in the control group had progressed.
• The authors concluded that “resin infiltration in conjunction with fluoride varnish seems promising for controlling proximal lesion progression on deciduous molar teeth.”

        (Caries Res 2010; 44:41-46) 

 

May - 2010

Breastfeeding reduces the risk for the development of posterior crossbites in the primary dentition 

• Cross-sectional study of 1377 three-to-six-year-old Brazilian children.  Occlusal assessment was made by direct visual examination of teeth in centric occlusion.  “Posterior crossbite was diagnosed when an inverted relationship of occlusion was observed between at least 1 posterior tooth (deciduous canine or molar) in the transverse plane.”  Based upon maternal response to history of exclusive breastfeeding, the children were divided into four groups: Never breastfed; Breastfed for less than 6 months; Breastfed for 6 to 12 months; and Breastfed for more than 12 months.
• Most children were breastfed for less than 6 months (52%) or breastfed for 6 to 12 months (23%).  Prevalence of posterior crossbite in the various groups was as follows: Never breastfed (31%); Breastfed for less than 6 months (22%); Breastfed for 6 to 12 months (8%); and Breastfed for more than 12 months (2%).  The authors found “a statistically significant relationship between exclusive breastfeeding duration and the prevalence of posterior crossbite.”

         (Am J Orthod Dentofacial Orthop 2010; 137:54-58) 

 

April - 2010

Enamel hypoplasia in primary second molars maybe associated with increased risk for dental caries

• The objective of this study was to examine the relationship between enamel hypoplasia and caries experience in primary second molars of children (n = 491) from the longitudinal cohort Iowa Fluoride Study.  Dental examinations were conducted at 5 years and 9 years of age and defective enamel formation such as pits and linear grooves were recorded as enamel hypoplasia.  Caries lesions were defined as cavitated and/or filled primary second molars.   
• The authors found that the percentage of hypoplastic primary seconds molars with caries increased from 28 percent at 5 years of age to 42 percent at 9 years of age while the percentage of non-hypoplastic primary seconds molars with caries increased from 8 percent to 18 percent.  They concluded that “teeth of subjects with enamel hypoplasia had a significantly higher risk for caries at age 5 and 9 after controlling for other risk factors.” 
• Reviewer’s note:  Conclusions from this study should be interpreted with caution and are more suggestive than definitive.  The number of primary second molars with enamel hypoplasia was quite low (n = 32; 1.7%).  The number of hypoplastic primary seconds molars with caries increased from 9 at 5 years of age to 13 at 9 years of age.  Meanwhile the number of primary second molars without hypoplasia and manifesting caries more than doubled from 141 at 5 years of age to 335 at 9 years of age. 

         (Caries Res 2009; 43:345-353)

March - 2010

Enamel defects in permanent first molars are associated with neonatal health factors

• Children (n = 550) from Western Australia were examined, around the time of their enrollment in grade school, for determination of the type and extent of enamel defects in permanent first molars.  Prior to the eruption of the permanent first molars, “parents completed a questionnaire about the health status of the child’s mother during the last trimester of pregnancy, mother’s smoking habits, the birthing process, and the child’s health for the first three years.”  The teeth were examined at a school dental clinic using a mirror and probe under standard dental lighting.  Gross debris was removed and the teeth were air-dried for three to five seconds before examination. 
• Prevalence of white diffuse enamel defects (45%) in permanent first molars were the most common followed by demarcated enamel defects (16%).  “The presence of enamel defects on the first permanent molars was also associated with the presence of enamel defects in the permanent incisors.”  As compared to healthy children, a higher proportion of children with a medical condition during the neonatal period had enamel defects in permanent first molars.  “White diffuse defects were more likely if the child was premature or had other health complications (most commonly jaundice) and the risk of demarcated defects was nearly seven times higher if the child experienced infections following birth.” 
• The author speculated that diffuse opacities may be associated with prolonged low-grade insults with the defects occurring both in the secretory phase as well as the maturation phase of enamel formation.  It was further speculated that demarcated defects may occur as a result of damage to the ameloblasts during the early or late maturation phase of enamel formation but with the cells recovering and resuming their normal function.  

         (Community Dent Oral Epidemiol 2009; 37:405-415)

 

February - 2010

Teeth with partially or fully lost fissure sealants are not at higher risk for developing caries

• In their literature review, the authors note that “sealant effectiveness is linked to sealant retention, and a retained sealant has been shown to be 100 percent effective.” 
• The authors conducted analysis of seven studies of resin-based fissure sealants, three of them with light-cured sealants, three with self-cured sealants, and one study with both types of sealants.  All studies used the split-mouth design with no re-application of lost sealant. 
• Based upon the data computations, the authors concluded that “teeth with fully or partially lost sealant were not at a higher risk of developing caries than were teeth that had never been sealed.”  The authors conclude that their “findings suggest that heightened concern about partially lost sealants trapping food and thus increasing the risk of caries development may be unfounded.” 

        (J Am Dent Assoc 2009; 140:415-423)

 

January - 2010

Typical longitudinal fluoride intake by United States children shows only weak association with bone mineral content or bone mineral density at 11 years of age

• Children participating in the Iowa Fluoride Study/Iowa Bone Development Study (n = 481) received bone examinations at 11 years of age.  Bone examinations included dual-energy X-ray absorptiometry scans of proximal femur (hip), lumbar spine and the whole body.  Bone mineral content and bone mineral density were related to fluoride intake (assessed by means of questionnaires at frequent intervals since infancy). 
• Water provided the majority of the mean daily fluoride intake which was estimated to be 0.68 mg from birth to 11 years of age (range was 0.54 to 0.81 mg F over different periods).  The authors noted that girls had lower mean F intake than boys with the mean mg F/kg/day declining consistently with increasing age in both boys and girls.   
• The authors reported that associations between daily fluoride intake (mg F per day) with bone mineral content and bone mineral density were weak and not statistically significant.  The authors noted that “the results of this study provide no evidence that fluoride intakes have consequences for bone outcomes at age 11 years in girls or boys within these ranges, which are probably typical for most children in the United States.” 

         (Community Dent Oral Epidemiol 2009; 37:416-426)