Occlusal force and occlusal contact reestablishment with resin-bonded fixed partial dental prostheses using the Dahl concept: A clinical study

Posterior two-unit cantilevered zirconia resin-bonded fixed partial dentures: A 3-year prospective single-arm clinical trial

OBJECTIVES

To evaluate the longevity of cantilevered zirconia-based resin-bonded fixed partial dentures (RBFPDs) in replacing missing posterior teeth, as well as the quality of life and patient satisfaction experienced by those receiving zirconia RBFPDs.

METHODS

A prospective single-arm uncontrolled clinical trial was conducted to replace one or more missing premolars or molars with a span of 5 to 8 mm using cantilevered zirconia RBFPDs. Thirty-six participants with 40 prostheses were recruited and underwent a 3-year clinical evaluation. The retainer designs included a minimum thickness of 0.8 mm, a minimum of 200° circumferential wraparound with an occlusal bar, and a connector dimension of 3 × 3 mm. Patient-reported outcomes, including patient satisfaction and Oral Health Impact Profile (OHIP), were assessed.

RESULTS

The average age of participants was 45.8 years, and 72.5 % were women. The success rate of the posterior zirconia RBFPDs was 76.2 %, with an estimated mean success duration of 46.1 months. The survival rate was 88.1 %, with an estimated mean survival duration of 49.4 months. Participants were highly satisfied with the treatment, achieving an average satisfaction score of 80.8 ± 11.9. Participants' total OHIP scores decreased from 52.3 to 39.6 after 3 years, indicating a significant improvement in oral health-related quality of life (P = 0.009).

CONCLUSIONS

After 3 years, a moderately high survival rate and favourable patient-reported outcomes of posterior cantilevered zirconia RBFPDs were achieved. Therefore, it can be recommended as a conservative treatment option to replace missing posterior teeth, provided that retainer design considerations are taken into account.

CLINICAL SIGNIFICANCE

Cantilevered zirconia RBFPDs for posterior teeth can serve as a conservative treatment option that is both aesthetically pleasing and biocompatible. It offers a more cost-effective alternative compared to dental implants, which are often prohibitively expensive for the majority of patients. This approach has the potential to greatly improve patient-reported outcomes.

Aspects of Occlusal Recordings Performed with the T-Scan System and with the Medit Intraoral Scanner

INTRODUCTION

Dental occlusion refers to the static and dynamic relationships that are established between the teeth of the two arches and is an important factor in the homeostasis of the dento-maxillary system. The objective of the present study was to compare two digital occlusal analysis systems: the T-Scan III system and the Medit I600 intraoral scanner.

MATERIALS AND METHODS

The study was carried out on 20 students from the Faculty of Dental Medicine Craiova, whose dental occlusion was assessed with the T-Scan III system and with the Medit I600 intraoral scanner. Dental occlusion was assessed in the maximum intercuspation position, the edge-to-edge protrusion position, and the edge-to-edge position in right and left laterotrusion. The images of the 2D occlusal contact areas obtained by both methods were converted to .jpeg format and then transferred to Adobe Photoshop CS6 2021 (Adobe Systems, San Jose, CA, USA) for comparison. The recorded data were statistically processed.

RESULTS

Analyzing the data provided by the two digital occlusal analysis systems, it was found that the T-Scan III system provided data related to the amplitude of the occlusal forces, the surface on which they were distributed (the contact surface), the dynamics of the occlusal contacts, and the proportion in which they were distributed at the level of the two hemiarches, and the Medit I600 intraoral scanner performed an evaluation of the occlusal interface of the two arches, highlighting the extent of the contact areas with the degree of overlapping of the occlusal components. Although both methods of occlusal analysis recorded the highest values for the maximum intercuspation position, the results could not be compared.

CONCLUSIONS

The two digital systems provide different data in occlusal analysis. As the T-Scan III system is considered the gold standard for occlusal analysis, more studies are needed to understand the data provided by the Medit I600 intraoral scanner and their significance.

Creating space for a resin-bonded fixed partial denture retainer by using the Dahl concept

A technique is presented for creating interocclusal space for a resin-bonded fixed partial denture retainer by applying the Dahl concept. A missing mandibular first molar was replaced with a cantilevered resin-bonded fixed partial denture and had been successfully retained at the 9-year clinical review.

Patient satisfaction following resin-bonded fixed dental prostheses cemented by using the Dahl concept

OBJECTIVE

Resin-bonded fixed dental prostheses (RBFDPs) cemented at an increased occlusal vertical dimension (OVD) (the Dahl concept) to create space for a metal retainer remains controversial because of the lack of reported clinical studies. This study analyzed the demographic (age and sex) and clinical factors (location and arch of prosthesis) affecting the patients' perception of RBFDPs cemented at an increased OVD.

MATERIAL AND METHODS

Twenty-eight participants treated with cantilevered RBFDP at an increased OVD were prospectively recruited. They were asked to answer a validated patient satisfaction questionnaire based on six parameters during the 12-week review visit.

RESULTS

71.4% of the participants were completely satisfied with the color, shape, and function. Twenty-one (75%) participants reported no complaints about the prostheses. 89.3% will recommend this treatment option to others. There was a significant difference between males and females in avoiding loading on the prostheses (p = 0.015). The level of satisfaction did not differ by age, ethnicity, location, and arch of the prostheses (p > 0.05).

CONCLUSIONS

Patient satisfaction toward RBFDP cemented by using the Dahl approach was generally high on all the parameters at the 12-week review visit.

Structural Integrity of Anterior Ceramic Resin-Bonded Fixed Partial Denture: A Finite Element Analysis Study

This study was conducted as a means to evaluate the stress distribution patterns of anterior ceramic resin-bonded fixed partial dentures derived from different materials and numerous connector designs that had various loading conditions imposed onto them through the utilization of the finite element method. A finite element model was established on the basis of the cone beam computed tomography image of a cantilevered resin-bonded fixed partial denture with a central incisor as an abutment and a lateral incisor as a pontic. Sixteen finite element models representing different conditions were simulated with lithium disilicate and zirconia. Connector height, width, and shape were set as the geometric parameters. Static loads of 100 N, 150 N, and 200 N were applied at 45 degrees to the pontic. The maximum equivalent stress values obtained for all finite element models were compared with the ultimate strengths of their materials. Higher load exhibited greater maximum equivalent stress in both materials, regardless of the connector width and shape. Loadings of 200 N and 150 N that were correspondingly simulated on lithium disilicate prostheses of all shapes and dimensions resulted in connector fractures. On the contrary, loadings of 200 N, 150 N, and 100 N with rectangular-shaped connectors correspondingly simulated on zirconia were able to withstand the loads. However, two of the trapezoidal-shaped zirconia connectors were unable to withstand the loads and resulted in fractures. It can be deduced that material type, shape, and connector dimensions concurrently influenced the integrity of the bridge.

When (and when not) to use the Dahl Concept

The Dahl Concept describes the re-establishment of occlusal contacts after the provision of a planned localised appliance or restoration in supraocclusion. Initially developed to create space for prosthetic rehabilitation of anterior teeth suffering from localised wear, the principle has later been successfully applied to a variety of situations, including the Hall technique and resin-bonded bridges cemented in supraocclusion. Despite high levels of success seen in the relevant literature and widespread adoption in specialist care, the wider profession appears to be far more cautious in its use. This article aims to provide a brief summary of the Dahl Concept and discuss the local and general factors that influence its successful implementation in the hope of promoting its increased adoption by the broader dental profession.