Bonding of resin composite precured or postcured to primary dentin.

PURPOSE: The purpose of this study was to examine in vitro the effect of cure mode on the shear bond strength (SBS), failure mode (FM), microleakage (ML), and resin tag penetration (RTP) of two resin composite (RC)/adhesive systems: (1) Clearfil Majesty Esthetic/Clearfil SE Bond (CME/SEB); and (2) TPH 3 Micro Matrix Restorative/Prime&Bond NT (TPH/P&B). METHODS: Paired RC samples (10 CME/SEB; 10 TPH/P&B) were precured or postcured with adhesive on primary molar dentinal substrates and tested for SBS (10 per group); debonded surfaces were examined. Cavities (Class V) in extracted primary molars were restored (20 CME/SEB; 20 TPH/P&B), following precuring or postcuring the adhesive, and examined for ML (eight per group) and RTP (two per group). RESULTS: Mean SBS (MPa) values differed: precured CME/SEB exceeded postcured CME/SEB (20.16±2.70 versus 10.97±4.39; P<.001), and postcured TPH/P&B exceeded precured TPH/P&B (14.17±3.73 versus 11.10±2.62; P=.007). The FM differed between systems: CME/SEB: precured (four adhesive-dentin; six mixed), postcured (10 adhesive-dentin); TPH/P&B: precured (10 adhesive-dentin), postcured (nine adhesive-dentin; one mixed). Only one specimen showed true ML (postcured TPH/P&B). The RTP was greater in postcured than precured specimens. CONCLUSION: Precured CME/SEB was deemed superior for restoration of primary teeth, despite extra time required clinically to precure the adhesive.

Distribution and severity of molar hypomineralisation: trial of a new severity index.

BACKGROUND: Current molar hypomineralisation (MH) indices do not guide clinicians in management of affected dentitions, and treatment is based on individual judgment. AIM: The aims of this study were to describe characteristics of MH and molar incisor hypomineralisation (MIH) and trial the new Molar Hypomineralisation Severity Index (MHSI). DESIGN: First permanent molars (FPMs) and permanent incisors (PIs) in 283 affected children were examined for hypomineralisation characteristics [defect colour, location, post-eruptive breakdown (PEB); restorations placed/replaced/atypical; sensitivity]. The MHSI scores were compared with treatment received (152 children). RESULTS: Mean (SD) affected teeth/dentition were as follows: FPMs: 3.2 (1.0) and PIs: 1.6 (1.6). Affected FPMs showed no arch or quadrant predilection; maxillary central PIs were affected particularly. As affected FPMs/dentition increased, MIH diagnoses also increased (P = 0.009). Among FPMs, defects most prevalent were brown (47%) and cuspal (74%); 67% showed PEB. Before study entry, 43% of FPMs had restorations placed/replaced. Among PIs, white defects were common (65%) on smooth surfaces; sensitivity was rare. Affected FPMs received more restorations and extractions than unaffected FPMs (P = 0.0001). As MHSI scores increased, FPM treatments/dentition increased (number, invasiveness). All characteristics were significant in predicting treatment (logistic regression model). CONCLUSIONS: A spectrum from MH to MIH occurred. The MHSI characteristics were predictive of the treatment of affected FPMs and can guide management.

Bonding of resin composite to caries-affected dentin after Carisolv(®) treatment.

PURPOSE: The purpose of this study was to investigate the effect of Carisolv(®) on resin composite adhesion on caries-affected dentin. METHODS: Carious lesion specimens (N =46) were prepared from 45 extracted primary molars: Group 1 (N =23)-chemomechanical (Carisolv(®)) treatment; Group 2 (N =23)-rotary instrumentation; and Group 3 (N =23)-caries-free specimens from 20 noncarious primary molars. After caries removal (Groups 1 and 2) or washing and drying (Group 3), a resin composite rod (2-mm high, 0.975-mm diameter) was bonded vertically to dentin. Specimens were stressed at constant displacement (1.0 mm/minute) to failure; treated surfaces were examined under a scanning electron microscope. RESULTS: The mean (±SD) microshear bond strengths of resin composite to dentin were: Group 1=6.69 (±4.08) MPa; Group 2=10.31 (±5.47) MPa; and Group 3=7.16 (±6.64) MPa. The mean bond strength of resin composite of Group 2 significantly exceeded that of Groups 1 (P=.02) and 3 (P=.01); Groups 1 and 3 did not differ significantly. There was no significant association between failure mode and treatment type (P=.22) or mean bond strength (P=.44). Carisolv(®) removed the smear layer or limited its formation, producing demineralization incompletely infiltrated by resin composite. CONCLUSION: Chemomechanical treatment of caries-affected dentin of primary teeth did not adversely affect resin composite bonding.

Molar incisor hypomineralization: review and recommendations for clinical management.

Molar incisor hypomineralization (MIH) describes the clinical picture of hypomineralization of systemic origin affecting one or more first permanent molars (FPMs) that are associated frequently with affected incisors. Etiological associations with systemic conditions or environmental insults during the child's first 3 years have been implicated. The complex care involved in treating affected children must address their behavior and anxiety, aiming to provide a durable restoration under pain-free conditions. The challenges include adequate anaesthesia, suitable cavity design, and choice of restorative materials. Restorations in hypomineralized molars appear to fail frequently; there is little evidence-based literature to facilitate clinical decisions on cavity design and material choice. A 6-step approach to management is described: (1) risk identification; (2) early diagnosis; (3) remineralization and desensitization; (4) prevention of caries and posteruption breakdown; (5) restorations and extractions; and (6) maintenance. The high prevalence of MIH indicates the need for research to clarify etiological factors and improve the durability of restorations in affected teeth. The purpose of this paper was to describe the diagnosis, prevalence, putative etiological factors, and features of hypomineralized enamel in molar incisor hypomineralization and to present a sequential approach to management.

Microshear bond strength of resin composite to teeth affected by molar hypomineralization using 2 adhesive systems.

PURPOSE: When restoring hypomineralized first permanent molars, placement of cavo-surface margins can be difficult to ascertain due to uncertainty of the bonding capability of the tooth surface. The purpose of this study was to investigate the adhesion of resin composite bonded to control and hypomineralized enamel with an all-etch single-bottle adhesive or self-etching primer adhesive. METHODS: Specimens of control enamel (N=44) and hypomineralized enamel (N=45) had a 0.975-mm diameter composite rod (Filtek Supreme Universal Restorative) bonded with either 3M ESPE Single Bond or Clearfil SE Bond following manufacturers' instructions. Specimens were stressed in shear at 1 mm/min to failure (microshear bond strength). Etched enamel surfaces and enamel-adhesive interfaces were examined under scanning electron microscopy. RESULTS: The microshear bond strength (MPa) of resin composite bonded to hypomineralized enamel was significantly lower than for control enamel (3M ESPE Single Bond=7.08 +/- 4.90 vs 16.27 +/- 10.04; Clearfil SE Bond=10.39 +/- 7.56 vs 19.63 +/- 7.42; P=.001). Fractures were predominantly adhesive in control enamel and cohesive in hypomineralized enamel. Scotchbond etchant produced deep interprismatic and intercrystal porosity in control enamel and shallow etch patterns with minimal intercrystal porosity in hypomineralized enamel. Control enamel appeared almost unaffected by SE Primer; hypomineralized enamel showed shallow etching. The hypomineralized enamel-adhesive interface was porous with cracks in the enamel. The control enamel-adhesive interface displayed a hybrid layer of even thickness. CONCLUSIONS: The microshear bond strength of resin composite bonded to hypomineralized enamel was significantly lower than for control enamel. This was supported by differences seen in etch patterns and at the enamel-adhesive interface.

Microtensile bond strength of tooth-colored materials to primary tooth dentin.

PURPOSE: This study measured the microtensile bond strengths of 2 tooth-colored restorative materials with and without conditioning of primary teeth dentin, and examined the micromorphology of the debonded surfaces and material-dentin interfaces. METHODS: Cylindrical specimens of packable composite resin (PCR) and resin-modified glass ionomer cement (RMGIC) bonded to dentin of primary teeth were ground to an hourglass shape and tested for microtensile bond strength. The debonded surfaces and material-dentin interfaces were prepared and examined under a scanning electron microscope (SEM). RESULTS: The microtensile bond strength values (mean +/- SD, in MPa) of PCR (Filtek P60 with Single Bond) and RMGIC (Fuji II LC), with or without the application of Cavity Conditioner (14.8 +/- 5.36, 12.01 +/- 4.43, 11.94 +/- 4.60, respectively), did not differ significantly (P > .05). Partial adhesive and partial cohesive failures within the restorative material predominated. The distributions of failure modes did not differ significantly between groups (P > .05). Under SEM, each material was seen to be closely adapted to dentin. Dentinal tubules were enlarged with etching, and the depth of penetration of resin tags of PCR was greater than for RMGIC. Smear plugs were incompletely removed by cavity conditioning. CONCLUSIONS: The bond strength of the PCR, Filtek P60 with Single Bond, to dentin of primary teeth was comparable to that of the RMGIC, Fuji II LC. Conditioning of the cavity preparation with Cavity Conditioner did not improve the bond strength of Fuji II LC. The distribution of failure modes did not differ between materials.

Assessing growth and development of the facial profile.

The study of growth and development of the facial profile is of interest to clinicians and researchers in the fields of pediatric dentistry, orthodontics, and craniofacial surgery, enabling diagnosis, planning, and evaluation of treatment. Until recently, craniofacial studies addressed facial growth, facial asymmetry, and gender differences by examining changes in size. However, size changes alone do not represent fully the complicated process of craniofacial growth which also involves changes in shape. The shape of the facial profile can now be quantified with Fourier analysis, contributing to a better understanding of growth. A combination of recently developed methods, such as 3-dimensional facial morphometry and Fourier analysis, should allow a more comprehensive knowledge of growth and development of the craniofacial structures, including the facial profile. This article examines various methods for assessing facial growth and development currently available with particular reference to the facial profile, and addresses the value of Fourier analysis in assessing shape changes.

The effects of cavity preparation and lamination on bond strength and fracture of tooth-colored restorations in primary molars.

PURPOSE: This in vitro study compared bond strength and fracture modes of tooth-colored restorations in 2 types of cavity preparations in human primary molars. METHODS: Standardized Class II cavities (40 dovetail and 40 box-only preparations) in extracted human primary molars were restored with packable composite resin (PC), resin-modified glass ionomer cement (RMGIC), resin-modified glass ionomer/packable composite resin laminate (RMGIC/PC), or resin-modified glass ionomer/packable composite resin laminate with an experimental bonding agent, K-14 (RMGIC/K-14/PC). The ultimate load at fracture was measured on marginal ridges, and fractured surfaces were examined microscopically. RESULTS: The mean (+/-SD) ultimate load at fracture (ULF, in Newtons) of PC and RMGIC/K-14/PC in box-only preparations (400+/-98; 386+/-82) did not differ significantly from that found in dovetail preparations (377+/-80; 317+/-92), and the mean ULF of RMGIC and RMGIC/PC in box-only preparations (307+/-44; 325+/-72) did not differ significantly from that in dovetail preparations (352+/-71; 353+/-70). No interactions were seen between materials and preparations (P=.09). Fracture modes for restorations in dovetail (predominantly mixed) and box-only preparations (predominantly mixed and adhesive) differed significantly (P=.003), but not between restorative procedures (P=.052). CONCLUSIONS: Tooth-colored restorations placed in vitro in box-only preparations did not differ in fracture resistance from those placed in dovetail preparations. On fracture loading, resin-modified glass ionomer restorations placed in box-only preparations were more likely to show adhesive failure than those placed in dovetail preparations.