Comparison Between Conventional and Neutral Zone CAD/CAM Complete Dentures in Muscle Activity and Occlusal Accuracy

Comparison Between Conventional and Neutral Zone CAD/CAM Complete Dentures in Muscle Activity and Occlusal Accuracy

Comparison of Electromyographic Muscle Activity and Occlusal Accuracy Between Conventional and Neutral Zone CAD/CAM Complete Dentures (Randomized Controlled Clinical Trial)

A within-subject cross-over study is done on eight completely edentulous patients to compare two different complete removable dentures. Group I: CAD-CAM ( computer-aided design/computer-aided manufacturing) conventional complete dentures designed based on the software algorithms; Group II: CAD-CAM neutral zone complete dentures designed based on the neutral zone concept. Occlusal analysis is done by the T-Scan device, and evaluation of muscle activity is conducted by electromyography at insertion time, two weeks after insertion time, and one month after insertion time.

This study is designed as a randomized clinical trial applying a within-subject comparison of two different complete denture types as follows; group I: CAD-CAM conventional complete dentures designed based on the software algorithms, group II: CAD-CAM neutral zone complete dentures designed based on the neutral zone concept. The study will be carried out on eight completely edentulous patients, each patient will receive two sets of complete dentures in a random sequence. For each denture set, at the denture insertion visit occlusal analysis and equilibration will be performed with the aid of the T-Scan device, also EMG evaluation of muscle activity will be conducted. Two weeks after, the patients will be recalled to reanalyze the occlusion after the denture settles using the T-scan computerized system. One month after the last recall visit, the EMG evaluation of muscle activity will be conducted again. The EMG and T-scan recording data will be collected and analyzed to compare the two denture types

The patient will be provided by a complete removable denture designed based on the software algorithms to restore his missing teeth which will be manufactured by CAD/CAM milling of monolithic methacrylate blanks.

The patient will be provided with a complete removable denture designed according to the neutral-concept to restore his missing teeth, which will be manufactured by CAD/CAM milling of monolithic methacrylate blanks.

The patients will receive complete removable dentures designed based on the software algorithms and digitally manufactured using a milling machine.

The patients will receive complete removable dentures designed based on the neutral-zone concept and digitally manufactured using a milling machineز

The electromyography activity of the Masseter and Temporalis muscles will be evaluated during clenching, chewing of soft food, and chewing of hard food, at the time of denture insertion (baseline) and one month after baseline.The measuring unit is mv.

The percentage of occlusal force distribution will be evaluated for both dentures using the T-Scan computerized occlusal analysis system, at the time of denture insertion (baseline) and following baseline by two weeks after.

Inclusion Criteria: Patients who have been completely edentulous in both jaws (maxilla and mandible) for a long period. Patients with a resorbed mandibular ridge. Patients with a Class I maxillo-mandibular relationship Patients with adequate inter-arch space. Patients with good neuromuscular control. Patients without any tempo-mandibular disorder. Exclusion Criteria: Patients with any oral diseases that may affect complete denture construction Patients with bad oral hygiene. Patients with neuromuscular disorders. Patients with a history of parafunctional habits. Hysterical patients. Patients will undergo or have previously received chemotherapy or radiotherapy. Drug-addicted patients.

Ohkubo C, Shimpo H, Tokue A, Park EJ, Kim TH. Complete denture fabrication using piezography and CAD-CAM: A clinical report. J Prosthet Dent. 2018 Mar;119(3):334-338. doi: 10.1016/j.prosdent.2017.04.013. Epub 2017 Jul 15.

Cagna DR, Massad JJ, Schiesser FJ. The neutral zone revisited: from historical concepts to modern application. J Prosthet Dent. 2009 Jun;101(6):405-12. doi: 10.1016/S0022-3913(09)60087-1.