Date of Award

6-26-2026

Thesis Type

PhD

Document Type

Thesis

Divisions

Faculty of Dentistry

Department

Department of Restorative Dentistry

Institution

Universiti Malaya

Abstract

Marginal adaptation of an obturator at the maxillary defect margin is essential for achieving an effective oronasal seal and satisfactory prosthetic function. However, evidence regarding the effects of fabrication techniques and 3D-printing build orientation on obturator-base adaptation remains limited. This in vitro experimental study assessed marginal adaptation of obturator bases at the maxillary defect margin and examined the effects of 3D-printing build orientation and fabrication technique/material. Fifty obturator bases were fabricated on an edentulous maxillary master cast with a Class I midline defect in two phases. In Phase I, obturator bases were 3D printed at 0°, 45°, and 90° build orientations (n=10/group). In Phase II, the selected 3D-printed photopolymerise resin (3D-PR; n=10) group at 45° was compared with compression-moulded heat-polymerised PMMA (CM-PMMA; n=10) and injection-moulded thermoplastic polyamide (IM-TP; n=10). Marginal adaptation was evaluated by scanning the master cast and specimens, performing 3D superimposition in Geomagic Control X, and calculating root mean square (RMS) deviation values (mm) for overall and regional defect-margin areas (anterior, posterior, medial, lateral). Data were normally distributed (Shapiro–Wilk, p>0.05) and analysed using one-way ANOVA with LSD post-hoc tests (α=0.05). Overall marginal adaptation did not differ significantly among build orientations (0°= 0.12956±0.03316, 45°= 0.12966±0.02925, 90°= 0.13329±0.01918; p=0.943), although significant regional differences were observed at the medial and lateral margins, with the lowest medial RMS at 45° (0.04976±0.01159) and the lowest lateral RMS at 0° (0.12827±0.02400). Fabrication technique/material significantly affected overall and regional adaptation (p< 0.05), with 3D-PR demonstrating the lowest overall RMS (0.12966±0.02925), followed by CM-PMMA (0.21297±0.03618), while IM-TP exhibited the highest overall RMS (0.27733±0.04788). In conclusion, fabrication technique significantly influences defect-margin adaptation, with the evaluated 3D-printing workflow producing superior overall adaptation compared with compression and injection moulding; build orientation showed region-dependent effects, supporting 45° as the preferred orientation when optimising adaptation at critical defect-margin regions.

Initial

khm

Additional Information

Thesis (PhD) – Faculty of Dentistry, Universiti Malaya, 2026.

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