A3 Tooth Loss and Dental Mobility

Topic

Tooth mobility is the combined result of three processes occurring in the tissues supporting the tooth: a reduction in the functional periodontal ligament area, increased gingival inflammation, and alveolar bone loss. The greater the reduction in the functional periodontal ligament area, the increase in gingival inflammation, and the alveolar bone loss, the greater the tooth mobility resulting from the combination of these three factors.

This behavior can be likened to a spring supporting the tooth: the effective stiffness of that spring decreases as alveolar bone loss progresses, and the lower the tooth's effective stiffness, the greater the clinically observed mobility.

When tooth mobility becomes sufficiently severe, the tooth can no longer fulfill its supporting function, leading to tooth loss. From that point on, the system lacks a tooth to distribute masticatory loads in that position, and this absence triggers subsequent changes in the neighboring teeth.

Tooth loss alters the distribution of masticatory loads on adjacent teeth and the opposing tooth in the opposite arch: the opposing tooth, having lost the contact that previously restrained it, extrudes into the empty space, while adjacent teeth migrate horizontally toward the edentulous area, tilting into the space left by the lost tooth.

Within the edentulous area resulting from tooth loss, the alveolar bone that previously supported loads transmitted by the lost tooth's root no longer receives that functional load; bone deprived of load tends to resorb, meaning the less functional load the alveolar bone in that area receives, the more its volume diminishes over time.

Beyond the edentulous area, tooth loss disrupts the occlusal balance of the entire arch by redistributing masticatory loads—previously shared among more teeth—across fewer points of contact. When this redistribution concentrates excessive masticatory load on specific teeth or the temporomandibular joint, it can overload the joint and trigger associated symptoms.

When an edentulous area is restored with a prosthesis supported by the edentulous ridge, the masticatory load received by the prosthesis is distributed among the system's various materials based on their relative stiffness: the stiffest material concentrates a proportionally higher load, while the more flexible material absorbs less.

Because a dental implant is far more rigid than the periodontal ligament supporting a natural tooth, it concentrates masticatory load differently than a natural tooth and creates a distinct stress distribution pattern in the surrounding pericrestal bone. While the mobility of a natural tooth relies on the flexibility provided by the periodontal ligament—as previously described—a dental implant lacks this shock-absorbing ligament, thereby transmitting masticatory load to the pericrestal bone in a much more direct and rigid manner.

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