Objective: Tooth loss leads to reduced occlusal contact area, altered jaw biomechanics, and diminished neuromuscular coordination, impairing both masticatory function and speech clarity. Edentulous patients often adapt by modifying food choices or swallowing behavior and may experience persistent phonetic disturbances. Maximum bite force is a validated measure of masticatory system performance, while speech intelligibility reflects the functional integration of a prosthesis within the oral cavity. This study aimed to objectively evaluate maximum bite force and speech intelligence among completely edentulous patients rehabilitated with different types of dental prostheses, compared to individuals with full natural dentition.

Methods: A cross-sectional study was conducted with 60 participants divided into six groups: (A) Hybrid Prosthesis (at least one arch) (B) Implant-Retained Overdentures (IROD) in both arches (C) Maxillary Complete Removable Dental Prosthesis (CRDP) with Mandibular IROD (D) Implant Bar-Supported Prosthesis (at least one arch) (E) Maxillary and Mandibular CRDP (F) Full Natural Dentition (control group)

IRB approval (Protocol #857207) and informed consent were obtained.

Maximum bite force was recorded using a bilateral molar bite force transducer. Participants performed three maximal-effort bites per side; total and unilateral bite force data were analyzed.

Speech intelligence was evaluated using a standardized dental articulation passage. A speech intelligibility scorer calculated the percentage of recognized words, averaged across three trials.

Results: Group F (Full Natural Dentition) exhibited the highest mean bite force (752.03 N), followed by Groups A (522.97 N), B (294.12 N), C (174.23 N), D (162.17 N), and E (72.13 N). Fold increases over Group E (complete dentures) were 10.4× (F), 7.3× (A), 4× (B), 2.4× (C), and 2.25× (D). Repeated-measures ANOVA confirmed that total bite force was significantly higher than unilateral values (1.5–1.8× greater). Males had significantly higher bite force than females (p < 0.01).

Speech intelligibility scores followed a similar gradient. Group F had the highest score (85.67%), followed by Groups A (70.13%), D (62.73%), C (58.17%), B (56.52%), and E (54.63%). Statistically significant differences were observed between Group E and Groups B, C, and D (p < 0.005). Fixed prostheses (Groups A and D) outperformed removable designs (Groups B, C, and E) in both bite force and speech performance. The superior speech outcomes associated with fixed prostheses are likely due to greater palatal stability and optimized tongue space. No gender-based differences were observed for speech scores.

Correlation analysis revealed moderate positive relationships between bite force and speech intelligence across prosthetic groups. Stronger masticatory capacity was associated with improved phonetic clarity in fixed and implant-retained prosthesis users, whereas weaker bite forces in complete denture users correlated with reduced intelligibility.

Conclusion: This study underscores the importance of assessing both masticatory and phonetic outcomes in prosthodontic rehabilitation. The findings establish a functional gradient of bite force across prosthetic designs:

Full Natural Dentition > Hybrid Prosthesis > IROD > Bar-Supported Prosthesis > CRDP + Mandibular IROD > CRDP.

Complete removable dental prosthesis exhibited only one-tenth the bite force of full natural dentition. Masticatory function improved 2.4× with a mandibular IROD, 4× with IROD in both arches, and 7.3× with a hybrid prosthesis. Fixed prostheses also yielded higher speech intelligibility, attributed to improved tongue space and palatal contours. While gender influenced bite force, it had no effect on speech.

Bite force transducers and intelligibility scorers offer practical, objective tools to guide treatment planning, monitor rehabilitation success, and support evidence-based prosthodontic care.