Mutational analysis of AXIN2, MSX1, and PAX9 in two Mexican oligodontia families.

The genes for axin inhibition protein 2 (AXIN2), msh homeobox 1 (MSX1), and paired box gene 9 (PAX9) are involved in tooth root formation and tooth development. Mutations of the AXIN2, MSX1, and PAX9 genes are associated with non-syndromic oligodontia. In this study, we investigated phenotype and AXIN2, MSX1, and PAX9 gene variations in two Mexican families with non-syndromic oligodontia. Individuals from two families underwent clinical examinations, including an intra-oral examination and panoramic radiograph. Retrospective data were reviewed, and peripheral blood samples were collected. The exons and exon-intronic boundaries of the AXIN2, MSX1, and PAX9 genes were sequenced and analyzed. Protein and messenger RNA structures were predicted using bioinformative software programs. Clinical and oral examinations revealed isolated non-syndromic oligodontia in the two Mexican families. The average number of missing teeth was 12. The sequence analysis of exons and exon-intronic regions of AXIN2, MSX1, and PAX9 revealed 11 single-nucleotide polymorphisms (SNPs), including seven in AXIN2, two in MSX1, and three in PAX9. One novel SNP of MSX1, c.476T>G (Leu159Arg), was found in all of the studied patients in the families. MSX1 Leu159Arg and PAX9 Ala240Pro change protein and messenger RNA structures. Our findings suggested that a combined reduction of MSX1 and PAX9 gene dosages increased the risk for oligodontia in the Mexican families, as in vivo investigation has indicated that interaction between Msx1 and Pax9 is required for tooth development.

Phenotype characterization and sequence analysis of BMP2 and BMP4 variants in two Mexican families with oligodontia.

Both BMP2 and BMP4 are involved in tooth development. We examined phenotypes and BMP2 and BMP4 gene variations in two Mexican oligodontia families. Physical and oral examinations and panoramic radiographs were performed on affected and unaffected members in these two families. The affected members lacked six or more teeth. DNA sequencing was performed to detect BMP2 and BMP4 gene variations. Three single nucleotide polymorphisms (SNPs) in BMP2 and BMP4 genes were identified in the two families, including one synonymous and two missense SNPs: BMP2 c261A>G, pS87S, BMP2 c570A>T, pR190S, and BMP4 c455T>C, pV152A. Among the six affected patients, 67% carried "GG" or "AG" genotype in BMP2 c261A>G and four were "TT" or "AT" genotype in BMP2 c570A>T (pR190S). Polymorphism of BMP4 c455T>C resulted in amino acid changes of Val/Ala (pV152A). BMP2 c261A>G and BMP4 c455T>C affect mRNA stability. This was the first time that BMP2 and BMP4 SNPs were observed in Mexican oligodontia families.

An in vitro investigation of the effects of glass inserts on the effective composite resin polymerization shrinkage.

We placed an MOD preparation in each of 12 permanent molars, then restored each tooth with a posterior composite resin by means of six different application techniques (I-polymerization as one complete unit; II--polymerization as one complete unit with glass inserts; III--polymerization in gingivo-occlusal increments; IV-polymerization in gingivo-occlusal increments with glass inserts; V--polymerization in bucco-lingual increments; and VI--polymerization in a gingival increment with glass inserts, then bucco-lingual increments). A precision strain gauge was attached to the buccal surface of each tooth and balanced at zero. After each increment was polymerized, the strain appearing on the strain gauge indicator was recorded. Each tooth was restored by use of all techniques; two teeth started with each technique. Results demonstrated the average microstrain units to be 127-I, 102-II, 105-III, 86-IV, 72-V, and 66-VI. A randomized block design was the format used for data evaluation. Scheffé's Test indicated that composite resin placement and polymerization in bucco-lingual increments (V) created significantly less cuspal deflection than polymerization as one complete unit, with or without glass inserts (I and II), p less than 0.001, and gingivo-occlusal increments (III), p less than 0.05. Placement and polymerization in a gingival increment with glass inserts, then bucco-lingual increments (VI), also created significantly less internal deflection than polymerization as one complete unit, with or without glass inserts (I and II), p less than 0.001, and gingivo-occlusal increments (III), p less than 0.005.

In vitro bond strengths and SEM evaluation of dentin bonding systems to different dentin substrates.

In comparison to enamel, bonding to normal dentin is a greater challenge because of its organic constituents, fluid-filed tubules, and variations in intrinsic composition. Bonding to sclerotic dentin is even more difficult. To evaluate the shear bond strengths of four adhesive systems to dentin substrates with different levels of mineralization, 120 extracted human teeth were randomly assigned to three groups (n = 40). After mid-coronal dentin was exposed, groups of specimens were artificially hypermineralized by immersion in a remineralizing solution, demineralized by means of an acetic acid demineralizing solution, or stored in distilled water to model sclerotic, carious, and normal dentin, respectively. Resin composite was bonded to dentin by use of commercial adhesive systems. After the specimens were thermocycled, shear bond strengths were determined in an Instron universal testing machine. Dentin substrates and resin/dentin interfaces were examined by SEM. For each adhesive system, the mean shear bond strength to normal dentin was significantly higher than that to either of the other substrates. Shear bond strengths to hypermineralized dentin were significantly higher than those to demineralized dentin with all adhesives except Prisma Universal Bond 3.

Effects of aged fluoride-containing restorative materials on recurrent root caries.

Accumulated evidence has illustrated that secondary caries is the major reason for the failure of amalgam and resin composite restorations. The purpose of this study was to assess the cariostatic effects of aged fluoride-containing restorative materials on the formation of secondary root caries. Fifty sound human molars were selected and randomly assigned to five material groups: non-fluoride-containing amalgam (NA), fluoride-containing amalgam (FA), non-fluoride-containing composite (NC), fluoride-containing composite (FC), and glass-ionomer cement (GIC). After standardized class V cavity preparations and placement of restorations, teeth within each group were randomly divided into two subgroups, "non-aged" and "aged". The aged subgroup was immersed in an inorganic buffer solution for 2 wks before being thermocycled. After being thermocycled and subjected to four cycles of caries formation in a bacterial model system, the teeth were sectioned. Depths of outer lesions and areas of lesions on the cavity walls were measured by polarized light microscopy. The results showed that the FA and GIC groups, whether aged or not, had significantly smaller outer lesion depth than the non-fluoride-containing NA and NC groups. After aging, the FA group demonstrated significantly greater lesion depth (p = 0.0002), while the GIC group exhibited no significant changes in lesion depths. The NA group had a greater wall lesion area than the NC group, while both demonstrated no significant changes following 2 weeks of aging. The FA and GIC groups had similar inhibition areas along the cavity walls, whereas both inhibition areas increased significantly after the aging process. It is concluded that the fluoride-containing amalgam and the glass-ionomer cement, even after a two-week aging process, can still elicit a significant preventive effect on recurrent root caries in an in vitro bacterial model system.

Two multi-center studies evaluating locally delivered doxycycline hyclate, placebo control, oral hygiene, and scaling and root planing in the treatment of periodontitis.

BACKGROUND: The clinical efficacy and safety of doxycycline hyclate (8.5% w/w) delivered subgingivally in a biodegradable polymer (DH) was compared to placebo control (VC), oral hygiene (OH), and scaling and root planing (SRP) in 2 multi-center studies. METHODS: Each study entered 411 patients who demonstrated moderate to severe periodontitis. Patients had 2 or more quadrants each with a minimum of 4 qualifying pockets > or =5 mm that bled on probing. At least 2 of the pockets were > or =7 mm. Treatment with DH, VC, OH, or SRP was provided at baseline and again at month 4. Clinical parameters were recorded monthly. RESULTS: DH and SRP resulted in nearly identical clinical changes over time in both studies. Mean 9 month clinical attachment level gain (ALG) was 0.8 mm for the DH group and 0.7 mm for the SRP group in Study 1, and 0.8 mm (DH) and 0.9 mm (SRP) in Study 2. Mean probing depth (PD) reduction was 1.1 mm for the DH group and 0.9 mm for the SRP group in Study 1 and 1.3 mm for both groups in Study 2. Frequency distributions showed an ALG > or =2 mm in 29% of DH sites versus 27% of SRP sites in Study 1 and 31% of DH sites versus 34% of SRP sites in Study 2. PD reductions > or =2 mm were seen in 32% of DH sites versus 31% of SRP sites in Study 1 and 41% of DH sites versus 43% of SRP sites in Study 2. Comparisons between DH, VC, and OH treatment groups showed DH treatment to be statistically superior to VC and OH. Safety data demonstrated a benign safety profile with use of the DH product. CONCLUSIONS: Results of this trial demonstrate that treatment of periodontitis with subgingivally delivered doxycycline in a biodegradable polymer is equally effective as scaling and root planing and superior in effect to placebo control and oral hygiene in reducing the clinical signs of adult periodontitis over a 9-month period. This represents positive changes resulting from the use of subgingivally applied doxycycline as scaling and root planing was not limited regarding time of the procedure or use of local anesthesia.

The effect of locally delivered controlled-release doxycycline or scaling and root planing on periodontal maintenance patients over 9 months.

BACKGROUND: This research report evaluates clinical changes resulting from local delivery of doxycycline hyclate (DH) or traditional scaling and root planing (SRP) in a group of patients undergoing supportive periodontal therapy (SPT). METHODS: In all, 141 patients received either DH (67) or SRP (74) treatment in sites > or =5 mm on one-half of their dentition at baseline and month 4. RESULTS: Clinical results were determined at month 9. Baseline mean probing depth recordings were similar between the two groups (DH = 5.9 mm; SRP = 5.9 mm). Mean month 9 results showed similar clinical results for attachment level gain (DH 0.7 mm; SRP 0.8 mm) and probing depth reduction (DH 1.3 mm; SRP 1.1 mm). Percentage of sites showing > or =2 mm attachment level gain at month 9 was 24.7% in the DH group and 21.2% in the SRP group. Thirty-nine percent (39%) of DH sites and 38% of SRP sites showed > or =2 mm probing depth reduction. When treated sides of the dentition were compared to untreated sides, DH showed a difference in disease activity (> or =2 mm attachment loss) from 19.3% (untreated) to 7.2% (treated); and SRP from 14.3% (untreated) to 8.1% (treated). CONCLUSIONS: Results show that both DH without concomitant mechanical instrumentation and SRP were equally effective as SPT in this patient group over the 9-month study period.

Posterior composite Class II restorations: in vitro comparison of preparation designs and restoration techniques.

The aim of this study was to evaluate conservative preparation designs for the restoration of Class II lesions with posterior resin composite. Fourteen primary and 14 permanent molars were obtained. Conservative modified MO and DO preparations were placed in half the teeth; conventional MO and DO preparations were placed in the remaining teeth. Randomly, a glass-ionomer liner was placed over the exposed dentin in one preparation of each tooth, a calcium hydroxide liner was placed in the remaining preparations. Posterior resin composite was placed in all teeth, and the teeth were loaded with a 17-kg force. Teeth were thermocycled, stored in 37 degrees C water, then immersed in 50% silver nitrate solution and placed in developer. The teeth were sectioned and photographed. Microleakage was calculated according to the depth of dye penetration, on a 6-degree scale. Results demonstrated the conservative modified restorations and conventional restorations, when glass-ionomer liner was used, to have less marginal microleakage, in both primary and permanent teeth, than their calcium hydroxide counterparts.

Evaluating the effects of fluoride-releasing dental materials on adjacent interproximal caries.

BACKGROUND: The authors examined several restorative materials to evaluate their ability to inhibit demineralization and enhance remineralization of incipient carious lesions on the interproximal enamel of teeth adjacent to those restored with the materials. METHODS: Twenty-one subjects in need of a crown on a mandibular molar and a Class II inlay on an adjacent tooth took part in this six-phase study. Artificial enamel lesions were created and positioned within the interproximal portion of a crown. Lesions were photographed with polarized light microscopy and characterized before and after 30-day intraoral exposures. Each phase included the placement of a new section in the crown model and a new Class II inlay restorative material in the adjacent tooth. RESULTS: Results demonstrated that nonfluoridated resin composite, fluoridated resin composite and resin-modified glass ionomer restorative materials, when placed in subjects who brushed with a fluoridated dentifrice, demonstrated significantly (P < .05) less enamel demineralization than the nonfluoridated resin composite control placed in subjects who brushed with a nonfluoridated dentifrice. The resin-modified glass ionomer cement, however, even when brushed with a nonfluoridated dentifrice, exhibited significantly (P < .05) less demineralization than the nonfluoridated resin composite control brushed with a nonfluoridated dentifrice. CONCLUSIONS: Resin-modified glass ionomer cement appears to significantly inhibit demineralization of interproximal enamel of teeth adjacent to those restored with the material. CLINICAL IMPLICATIONS: Resin-modified glass ionomer cement restorations can enhance prevention of enamel demineralization on adjacent teeth.

Clinical performance of resin-modified glass ionomer cement restorations in primary teeth. A retrospective evaluation.

BACKGROUND: The authors retrospectively evaluated the clinical performance of one resin-modified glass ionomer cement as a restorative material in Class I, Class II, Class III and Class V restorations in primary teeth. METHODS: A total of 306 patients who had received a total of 864 resin-modified glass ionomer restorations, which had been in their mouths for a minimum of three years, were included in this evaluation. The authors assessed the clinical observations recorded in patients' records and used bitewing radiographs to assess Class II restorations. RESULTS: The authors found an overall restoration success rate of 93.0 percent, with Class I restorations having a 92.6 percent success rate, Class II restorations having a 93.3 percent success rate, Class III restorations having a 100 percent success rate, and Class V restorations having a 98.0 percent success rate. CONCLUSIONS: The resin-modified glass ionomer cement functioned well as a Class I, Class II, Class III and Class V restorative material in primary teeth. CLINICAL IMPLICATIONS: Resin-modified glass ionomer restorative cement is a durable and reliable material to use for Class I, Class II, Class III and Class V restorations in primary teeth. Therefore, dentists have a proven alternative to silver amalgam and resin-based composite for primary tooth restoration.

Clinical performance and caries inhibition of resin-modified glass ionomer cement and amalgam restorations.

BACKGROUND: The authors clinically examined two restorative materials to evaluate their effectiveness in Class II restorations in primary molars and their ability to inhibit recurrent caries. METHODS: Forty subjects, each in need of two Class II restorations in primary molars, took part in this study. Each patient received one Class II restoration of resin-modified glass ionomer cement and one of amalgam. The authors evaluated the restorations at six-month, one-year, two-year and three-year recall appointments. On exfoliation, teeth with experimental restorations were retrieved and microscopically examined for inhibition of demineralization at restoration margins. RESULTS: The results of the clinical evaluation demonstrated no significant differences between the resin-modified glass ionomer cement restorations and the amalgam restorations (P < .05). Polarized light microscopic examination of the returned teeth that were restored as a part of this study indicated that the resin-modified glass ionomer cement had significantly less enamel demineralization at restoration margins than did amalgam (P < .0001). CONCLUSIONS: The resin-modified glass ionomer cement functioned clinically as well as amalgam for Class II restorations in primary molars. However, the resin-modified glass ionomer exhibited significantly less enamel demineralization at restoration margins than did amalgam. CLINICAL IMPLICATIONS: Resin-modified glass ionomer cement restorative material functions well for Class II restorations in primary molars and exhibits less recurrent caries at restoration margins than does amalgam.

Management of sports-related crown fractures.

Uncomplicated tooth crown fractures are the most common sports-related mouth injury and can have an excellent outcome if treated appropriately. Many times, however, crown fractures occur at the same time as concussion, luxation, displacement, or even avulsion injuries. This article discusses the treatment for and management of tooth crown fractures from sports-related injuries.

A comparison of glass-ionomer cement and calcium hydroxide liners in amalgam restorations.

This study compared the caries inhibition and microleakage of two liners under amalgam restorations. Thirty-two molars received mesio-occlusal and disto-occlusal Class II cavity preparations. Calcium hydroxide was randomly placed as a liner in one preparation of each tooth and glass-ionomer cement liner was placed in the other. Amalgam restorations were placed. Teeth were axially loaded and an acid-protective varnish was placed. Teeth were placed into artificial saliva for 3 months, thermocycled, and cycled through a caries challenge. Sections were obtained from 20 teeth and photographed under polarized light. The remaining teeth were placed in 2% basic fuchsin and sectioned. A t-test indicated that restorations with glass-ionomer cement liners exhibited significantly less demineralization and microleakage than did restorations with calcium hydroxide liners.

Composite resin inlays: a single appointment technique.

This article presents a time efficient technique for the fabrication and subsequent placement of a composite resin inlay. An inlay preparation is cut into a tooth and a polyvinylsiloxane impression is made. A polyether impression of the polyvinylsiloxane impression forms a die, then a composite resin inlay is fabricated on the die. The inlay is contoured and polished on the die and occlusion is evaluated clinically. The inlay has a final polymerization under intense light and vacuum pressure, then is cemented with a mixture of unfilled resin and hybrid composite. The technique allows an esthetic restoration to be placed in one appointment. The die provides easy access and rapid inlay fabrication. There is no need to place a separator on the prepared tooth, no chance of premature tooth bonding, and interproximal contact is easily achieved.

Treatment of "non-restorable" teeth. A case report.

The purpose of this article is to present a case report of the dental care for permanent teeth that were originally considered "non-restorable". The temporary placement of stainless steel crowns was completed, followed by traditional endodontic therapy. The crowns were used as build-up matrices, access being prepared in the occlusal of the crown. Glass ionomer silver was then placed, followed by marginal finishing. Although this report is an isolated case, and is considered as temporary treatment, there may be indications to consider this technique for clinical care, on an individual basis.

Enamel and dentin demineralization inhibition of fluoride-releasing materials.

Fluoride-releasing dental restorative materials may provide an additional benefit in preventive dentistry. Although not currently available in the United States, a fluoride-releasing amalgam has demonstrated recurrent caries inhibition at enamel and dentin restoration margins. Likewise, both chemical-cured and light-cured glass ionomer cements have demonstrated caries inhibition at enamel and dentin restoration margins. Fluoride-releasing resin composites have also consistently demonstrated recurrent caries inhibition at enamel margins, yet there are conflicting results whether caries inhibition occurs at dentin margins. Preliminary studies indicate that glass ionomer cement and fluoride-releasing resin composite have synergistic effects with fluoride rinses and fluoridated dentifrices, in the remineralization of incipient enamel caries. The materials may act as a fluoride delivery system. Upon exposure to additional external fluoride, the material surface undergoes an increase in fluoride. This fluoride is subsequently released and has demonstrated demineralization inhibition and even remineralization at adjacent tooth structure. Clinical research to evaluate these fluoride-releasing restorative materials may provide further information for clinical recommendations.

Glass inserts. A new dimension in restorative dentistry.

Pediatric restorative dentistry has traditionally involved the placement of a stainless steel crown following a pulpotomy in primary molars. The increased exposure to systemic and topical fluorides has significantly decreased smooth surface caries, yet occlusal pit and fissure caries remains a problem. Occlusal caries involving the pulp of primary molars, leaving the supporting walls intact, may be restored conservatively with the use of glass inserts. The glass inserts provide the major volume of the restoration, therefore a minimal amount of posterior composite resin is necessary. The glass inserts bond to composite resin, increase restoration strength, and reduce polymerization shrinkage which may cause cuspal deflection or marginal microleakage. A case is presented to describe a new material and the conceptual protocol for clinical use.

Caries inhibition by fluoride-releasing primers.

This study evaluated the caries inhibition of dentin primers with the addition of fluoride. Two standardized Class V preparations were placed in 20 molars, the gingival margin placed below the cementoenamel junction and the occlusal margin placed in enamel. Two dentin primers (Syntac and ScotchPrep) were placed in equal numbers of 20 preparations, according to manufacturer's instructions. Ammonium fluoride (10% by weight) was then added to these primers and they were placed in the remaining 20 preparations, opposing the non-fluoridated primer of the same system. All teeth were then restored with a non-fluoridated resin composite. All teeth were subjected to an artificial caries challenge (pH 4.2) for 5 days. Sections of 100 microns were obtained, photographed under polarized light microscopy, then demineralized areas were quantitated by digitization. Results demonstrated the mean areas (mm2 +/- S.D.) demineralization at 0.25 mm, 0.5 mm and 1.0 mm from the restoration margin to be: Syntac/fluoride (1.44 +/- 0.49, 1.68 +/- 0.54, 3.72 +/- 0.74); Syntac (1.99 +/- 0.58, 1.50 +/- 0.35, 2.98 +/- 1.26); ScotchPrep/fluoride (1.23 +/- 0.68, 1.55 +/- 0.64, 3.08 +/- 1.16); ScotchPrep (1.90 +/- 0.83, 1.71 +/- .038, 3.36 +/- 0.62). A paired t-test indicated primers with fluoride to demonstrate significantly less demineralization 0.25 mm from the restoration margin (P < 0.07).

Dentin pretreatment and caries inhibition by a fluoride-releasing resin.

The purpose of this study was to examine the effect that phosphoric acid etchant, used to remove the smear layer, may have on dentin demineralization inhibition. Fifteen molars had Class V preparations placed on the mesial and distal surfaces, the gingival seat being placed 1 mm below the cementoenamel junction. Randomly, one preparation of each tooth had etchant placed carefully on only enamel for 30 seconds. Etchant was placed on the gingival seat dentin of the remaining preparations, as well as the enamel for 30 seconds. A HEMA dentin primer containing maleic acid was placed and allowed to dry on the unetched dentin, then a Bis-GMA resin with tetrabutyl ammonium tetrafluoroborate was placed. Only the fluoridated resin was placed over the dentin that had been etched. All teeth were then restored with resin composite and subjected to an artificial caries challenge (pH 4.4) for 7 days. Sections 100 microns were obtained, photographed under polarized light microscopy and demineralized areas were digitized. Results demonstrated the mean area (mm2 +/- S.D.) demineralization 0.5 mm from the gingival margin to be: etched dentin (0.77 +/- 0.36); non-etched dentin (1.52 +/- 0.98). A t-test indicated that there was significantly less demineralization when the fluoridated resin came in direct contact with dentin that had the smear layer removed (P < 0.05).

A one-visit composite post-crown restoration: case report.

A prefabricated endodontic post was cemented with glass ionomer, then composite resin was used to build up a core and fabricate a crown restoration. This treatment has been successful through a 2-year observation period, and may represent a treatment alternative for certain clinical situations, in which traditional cast procedures are not acceptable to the patient. Further investigation is necessary to evaluate the longitudinal success of composite resin crowns.