New cavity forms in first deciduous molars which maximize dentin thickness between cavity and pulp chamber

Area of Science:

• Dentistry
• Pediatric Dentistry
• Dental Materials Science

Background:

• Preserving adequate dentin thickness beneath cavity preparations is crucial for maintaining tooth vitality and preventing pulpal complications in deciduous molars.
• Understanding the anatomical variations between upper and lower deciduous molars is essential for designing effective and conservative cavity preparations.
• Previous research has not comprehensively detailed the ideal dimensions and features of retentive cavities in human deciduous molars.

Purpose of the Study:

• To investigate and define ideal cavity preparation parameters in human first deciduous molars to ensure a minimum of 1 mm subcavitary dentin thickness.
• To evaluate the effectiveness of different cavity designs, including retentional grooves and dovetail shapes, in preserving dentin thickness and ensuring filling material retention.
• To provide quantitative measurements for cavity margins, cusp distances, wall depths, and gingival wall widths in both upper and lower first deciduous molars.

Main Methods:

• Sixty human extracted first deciduous molars (30 upper, 30 lower) were used to prepare ideal cavities with approximately 1 mm subcavitary dentin.
• Cavities incorporated retentional grooves to prevent filling material dislodgement.
• Transparent specimens were sectioned into 93-micron slices, reconstructed via computer, and analyzed for subcavitary dentin thickness and cavity dimensions.

Main Results:

• Optimal subcavitary dentin preservation in upper molars was achieved with lingual retentional grooves or mesio-distolingual dovetail shapes; lower molars tolerated various cavity forms.
• Cavity margins were displaced medially to cusp summits by 1.9 mm (buccal) and 1.2 mm (lingual) in upper molars, and 0.9 mm (buccal) and 0.6 mm (lingual) mesially, and 1.2 mm (buccal) and 1.0 mm (lingual) distally in lower molars.
• Cavity width to inter-cusp distance ratios were 1:3 (upper) and 2:5 (lower). Cavity depths varied, with gingival wall widths measuring 0.6-0.7 mm in both.

Conclusions:

• Specific cavity designs, particularly lingual grooves and dovetail preparations, are recommended for upper deciduous molars to maintain adequate dentin thickness.
• The study provides precise anatomical and dimensional data crucial for conservative cavity preparation in deciduous molars.
• These findings contribute to improved restorative techniques in pediatric dentistry, enhancing the longevity of dental fillings in primary teeth.