Changes in Occlusion Following a Prolonged Edentulous Period: A Review

ABSTRACT
Prolonged edentulism results in progressive anatomical and functional changes within the stomatognathic system, significantly influencing occlusal relationships and prosthodontic outcomes. The absence of natural teeth leads to continuous residual ridge resorption, reduction in occlusal vertical dimension, altered mandibular posture, neuromuscular adaptation, and temporomandibular joint remodeling. These changes complicate occlusal reconstruction and prosthetic rehabilitation. This review discusses occlusal alterations associated with long-standing edentulism and highlights their clinical relevance based on recent scientific evidence.^1,3
1. INTRODUCTION
Occlusion is a dynamic relationship between the maxillary and mandibular arches that ensures efficient mastication, phonation, aesthetics, and neuromuscular balance. Natural dentition provides occlusal stability and periodontal proprioception essential for controlled mandibular movements. When edentulism persists over a prolonged period, the loss of occlusal support initiates adaptive and degenerative changes affecting alveolar bone, masticatory muscles, and temporomandibular joints (TMJ).^1,3; Recent studies emphasize that the duration of edentulism plays a critical role in determining the severity of occlusal alterations and rehabilitation complexity.⁴
2. RESIDUAL RIDGE RESORPTION AND OCCLUSAL CHANGES
Residual ridge resorption (RRR) is a chronic and irreversible process following tooth extraction. The mandible exhibits more rapid and severe resorption than the maxilla, leading to altered maxillomandibular relationships and reduced denture stability.^3,4 Advanced ridge resorption can produce an apparent prognathic mandibular relationship, complicating occlusal plane establishment and tooth arrangement. CBCT-based studies confirm a strong association between prolonged edentulism and increased vertical and horizontal ridge loss.⁵
3. REDUCTION IN OCCLUSAL VERTICAL DIMENSION
Loss of teeth over an extended period often results in decreased occlusal vertical dimension (OVD) due to mandibular overclosure. Clinically, this manifests as reduced lower facial height, angular cheilitis, and compromised facial aesthetics. Functional consequences include impaired mastication, altered speech, and muscular fatigue.⁶
Recent systematic reviews highlight the importance of careful evaluation and gradual restoration of OVD to prevent patient discomfort and TMJ strain.^6,7
4. ALTERATIONS IN MANDIBULAR POSITION AND CENTRIC RELATION
Centric relation is a bone-determined mandibular position independent of tooth contact. In long-term edentulous patients, habitual closure patterns and neuromuscular adaptation may alter mandibular positioning, making accurate centric relation records challenging.⁷ Failure to identify these changes can result in occlusal discrepancies, denture instability, and patient dissatisfaction. Accurate recording techniques and verification are therefore essential.²
5. OCCLUSAL PLANE CHANGES
Uneven ridge resorption and loss of dental landmarks disrupt the orientation of the occlusal plane. An improperly established occlusal plane compromises denture retention, stability, and masticatory efficiency. Excessive deviation may also increase lateral forces, accelerating residual ridge resorption.⁶ Recent clinical studies stress the importance of using anatomical and functional landmarks to re-establish a physiologic occlusal plane in edentulous patients.⁶
6. TEMPOROMANDIBULAR JOINT ADAPTATIONS
The TMJ undergoes adaptive remodeling following prolonged edentulism due to altered occlusal loading and mandibular positioning. CBCT studies have demonstrated changes in condylar position and joint spaces after complete denture rehabilitation, indicating the adaptive capacity of the TMJ.⁹ While many patients remain asymptomatic, others may develop TMJ discomfort or functional limitations, particularly when occlusal discrepancies persist.^9,10
7. NEUROMUSCULAR ADAPTATION
Loss of periodontal mechanoreceptors reduces sensory feedback necessary for precise mandibular control. Edentulous patients rely primarily on mucosal receptors, resulting in altered chewing patterns and reduced bite force.^1,3 Neuromuscular adaptation occurs gradually, and patients often require an adjustment period to achieve functional efficiency with new prosthesis, especially after prolonged edentulism.²
8. CLINICAL IMPLICATIONS IN PROSTHODONTIC REHABILITATION
Understanding occlusal changes associated with long-term edentulism is critical for successful prosthodontic rehabilitation. Comprehensive evaluation of residual ridge morphology, vertical dimension, mandibular position, and occlusal plane orientation is essential.^3,6 Recent evidence supports the use of implant-supported overdentures to improve occlusal stability and reduce further ridge resorption in suitable patients.^4,5
9. CONCLUSION
Prolonged edentulism leads to significant occlusal alterations resulting from residual ridge resorption, reduction in vertical dimension, neuromuscular adaptation, and temporomandibular joint remodeling. These changes pose challenges during prosthodontic rehabilitation but can be effectively managed through accurate diagnosis, careful clinical procedures, and individualized treatment planning. Awareness of these occlusal changes is essential to restore functional, stable, and comfortable occlusion in long-term edentulous patients.^1-10
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