Using the neutral zone to obtain maxillomandibular relationship records for complete denture patients

Neutral zone recording in computer-guided implant prosthesis: A new digital neuromuscular approach

Background

Neutral zone (NZ) is a specific area in the oral cavity where muscular opposite forces are null. NZ represents the ideal zone for prosthesis placement. In this study, we compared digital implant planning using conventional technique and using NZ registration through piezography.

Methods

Sixty-tree implants were digitally planned. Angular deviation differences between traditional planned and NZ-planned implants were calculated. In addition, interferences with soft tissues (i.e., tongue and cheeks) were evaluated.

Results

We observed a significant difference between traditional technique and piezographic approach in terms of implants angulation (p = .003), independent of site. A 4.7% of the planned abutments with traditional technique were placed outside the NZ, causing conflict with soft tissues in the digital model.

Conclusions

Compared with traditional technique, piezography allows a significantly different exploitation of the nonconflict area, which potentially translates into better management of soft tissues and improved functionality of the implants.

Effect on patient satisfaction of mandibular denture tooth arrangement in the neutral zone

STATEMENT OF PROBLEM

The effect of the neutral zone (NZ) technique on different functional aspects (masticatory performance, speech, and muscle activity) has been studied objectively. Subjectively, some studies reported that their participants felt that NZ dentures were more stable, retentive, and comfortable than conventionally fabricated dentures. These studies, however, lacked a measurable assessment scale or a specifically designed questionnaire.

PURPOSE

The purpose of this within-subject, crossover clinical trial was to investigate patient satisfaction levels in edentulous patients after rehabilitation with dentures fabricated using the NZ concept as compared with conventional dentures using a specific, question-oriented patient satisfaction questionnaire.

MATERIAL AND METHODS

The clinical trial included 52 participants. Each received one set of conventional dentures and another fabricated based on the NZ concept with a 1-month wash-out period. Participants randomly chose 1 of 2 closed opaque envelopes with 2 denture sequences, either conventional then NZ or NZ then conventional. Hence, participants were blinded to the dentures they wore. Patient satisfaction with each denture type was assessed 6 weeks after insertion by a blinded staff member using a 5-scale questionnaire developed for the most important functional aspects (esthetics, masticatory ability, retention, stability, speech, and comfort). The Wilcoxon Signed Rank test was used to compare the satisfaction scores of the 2 denture types (α=.05).

RESULTS

Patient satisfaction scores were significantly higher with the NZ dentures than with the conventional dentures in all aspects; P=.001 for question 2 (opinion of denture appearance) and P<.001 for all other questions.

CONCLUSIONS

NZ dentures offer significantly higher levels of patient satisfaction than conventional dentures in all functional aspects (retention, stability, masticatory ability, and speech) as well as in comfort and appearance.

Recording an accurate maxillomandibular relationship by adding vertical stops to the occlusal rims

Complete denture fabrication includes accurate recording of the maxillomandibular relationship to ensure the functional requirements of occlusion and minimize the traumatic effects on the residual alveolar ridges. However, errors may occur when the occlusal rims have uneven and nonuniform occlusal contacts. The technique described is a straightforward method for recording an accurate silicone centric relationship record with dome-shaped baseplate wax added as vertical stops on the occlusal surface of the mandibular occlusal rim.

Lip and Lower Lid Supporting Prosthetic Appliance: A Unique Approach of Treating Unilateral Facial Paralysis

Along with function, aesthetics plays an important role in treating partially or completely edentulous patients. Ageing, trauma, tooth loss and neuromuscular disorders have a high impact on tonicity of facial musculature, elasticity of skin as well as function of muscles. Patients affected with Bell's palsy face functional, aesthetic as well as psychological impairment. Common problems are the partial closure of upper eyelid, sagging of lower eyelid and drooping of angle of mouth leading to facial asymmetry, along with difficulty in eating, drinking and speaking. The key to aesthetic restoration is to support and harmonize the collapsed facial musculature with the help of various prosthodontic treatment approaches. This case report attempts to focus on treating completely edentulous patient affected with Bell's palsy with special prosthesis supporting angle of mouth and lower eyelid using novel technique.

The Effect of Reading Aloud Exercises for Complete Denture Patients during the Functional Rehabilitation Period

PURPOSE

The focus of this study was to evaluate the effect of reading aloud on masticatory performance and patient satisfaction of patients rehabilitated with conventional complete dentures for the first time.

MATERIALS AND METHODS

Sixty-two edentulous patients who received conventional complete denture treatment for the first time were randomly divided into two equal groups. After insertion of the dentures, patients in group I were asked to read a news report three times per day for 4 weeks, while those in group II did not read. The reading duration increased by 5 minutes per week, from 5 minutes in the first week to 20 minutes in the fourth week. The patients' mouth opening during reading aloud was advised to gradually increase throughout the training project. Two and four weeks after insertion of the dentures, masticatory performance was assessed using the sieving method, and patient satisfaction was measured using a visual analogue scale, which combined the patient's perceptions in relation to comfort, esthetics, stability, ability to talk, and ability to chew.

RESULTS

There were significant improvements in masticatory performance with reading aloud exercises after the insertion of complete dentures (p < 0.001) at the 2- and 4-week follow-up visits. Masticatory performance also showed significant improvement within each group in the follow-up periods (p < 0.001). No significant differences were found between the two groups in patient satisfaction (p > 0.05) at 2 weeks, but at 4 weeks, patient satisfaction regarding stability, ability to talk, and ability to chew was significantly higher for group I (p < 0.001).

CONCLUSIONS

The results of this study suggest that reading aloud exercises significantly improved early masticatory performance and patient satisfaction for denture wearers who were treated with conventional complete dentures for the first time, and may be a useful clinical application for more effective denture treatment.

Cross-arch arrangement in complete denture prosthesis to manage an edentulous patient with oral submucous fibrosis and abnormal jaw relation

A patient with oral submucous fibrosis and resorbed ridges poses a challenge for prosthodontic rehabilitation because of the limited mouth opening and fibrotic mucosa. The fabrication of prosthesis is very difficult due to abnormal jaw relations, influencing the long-term prognosis of the patient. To present a case of oral submucous fibrosis with severely resorbed edentulous ridges which was successfully managed by adopting a modified technique in fabricating a complete denture prosthesis. A 55-year-old female patient with completely edentulous maxillary and mandibular arches diagnosed with oral submucous fibrosis was rehabilitated with complete dentures by recording neutral zone for resorbed mandibular ridge and by arranging the posterior teeth in cross arch relation for compensation of the abnormal jaw relations. The cross-arch arrangement of posterior teeth provides a more stable and retentive complete denture prosthesis for patients with severely resorbed ridges and a wider mandibular arch.

Kinesiographic study of deglutition in dentate individuals and complete denture wearers

Swallowing is used as a clinical method in prosthodontics to determine and record jaw relationships. The aim of this study was to perform a quantitative evaluation, in naturally dentate subjects and complete denture wearers, of three measurements associated with the mandibular position during the act of swallowing water: 1. intermaxillary distance on vertical axis; 2. anteroposterior deviation; and 3. lateral deviation. Two groups were selected: Group I (GI) included 40 subjects with complete dentition (mean age 45.27 yrs) and Group II (GII) included 40 bimaxillary edentate subjects, complete denture wearers (mean age 63.92 yrs). A kinesiographic instrument was used for analysis. Three records were taken for each measurement and a mean value obtained. It was concluded that: 1. intermaxillary distance on vertical axis and horizontal deviation were similar for both groups; 2. there was a significant intermaxillary distance on the vertical axis; and 3. for anteroposterior and lateral axis, results showed moderate deviation in relation to maximal intercuspation (MI).

A comparison of the accuracy of two methods used by pre-doctoral students to measure vertical dimension

STATEMENT OF PROBLEM

Measuring vertical dimension is a soft-tissue measurement. Therefore, inaccuracy may occur.

PURPOSE

The purpose of this study is to compare the accuracy of the Willis gauge method with the caliper method.

MATERIALS AND METHODS

The Willis gauge measures the distance between the septum of the nose and the chin. The caliper method measures the distance between reference points on the tip of the nose and the chin. Twenty predoctoral students applied both methods 10 times in measuring the rest vertical dimension (RVD) and the occlusal vertical dimension (OVD) of a single edentulous patient. The measurements obtained from one experienced clinician were selected as controls for the interocclusal distances (IOD) for the Willis and the caliper methods, respectively. One-sided t tests and a 1-sided nonparametric test were used to determine significant differences between the 2 methods (alpha=.05).

RESULTS

The variances in the RVD values for the Willis gauge method were higher than for the caliper method for most students. A Wilcoxon signed rank test showed that the accuracy of the OVD measurements for the caliper method was significantly better than for the Willis gauge method (P=.001). This was not the case for the RVD measurements (P=.073). The average IOD for the Willis method was significantly higher than the control IOD (P=.026). The average IOD for the caliper method was not significantly larger than the control (P=.1303).

CONCLUSION

This study showed that the use of the caliper method by predoctoral students was a significantly more reliable method of measuring the OVD for the patient evaluated.

Report on the determination of occlusal vertical dimension and centric relation using swallowing in edentulous patients

When constructing a complete denture, the correct vertical dimension of occlusion (VDO) and centric relation (CR) can be difficult to determine. The aim of this study was to compare the swallowing technique used to determine the maxillomandibular relationship with a conventional technique. Fifteen edentulous patients were selected, each having a complete denture. The VDO and CR were assessed using acrylic base plates and a Boley gauge. First, the VDO was established by means of the vertical dimension of rest (VDR) and interocclusal rest space, and the CR was obtained by mandibular manipulation. Secondly, the VDO and the antero-posterior mandibular position were determined using swallowing. All measurements were repeated three times and the average was calculated. The results showed that (i). the VDO determined by means of the swallowing method was reproducible and significantly higher than the one established from the VDR (P < 0.01), and (ii). the swallowing position was located 2 mm anterior to CR (P < 0.01) and was moderately reproducible. This study suggests that swallowing can be used to determine the vertical position but no as a reference position in the sagittal plane.