Removable Partial Denture Abutments Restored With Monolithic Zirconia Crowns

March 2, 2020 updated by: Hiroko Nagaoka

Removable Partial Denture Abutments Restored With Monolithic Zirconia Crowns: A Randomized Controlled Trial

The purpose of this study is to investigate the use of an all-ceramic dental crown material to restore the abutment teeth of partially-edentulous patients who need removable partial dentures (RPD). The outcomes of the treatment group (all-ceramic crowns) will be compared to a similarly-treated control group whose RPD abutment teeth are restored using conventional metal and metal-ceramic crowns. Primary outcomes of interest include crown survival, abutment tooth survival and RPD survival.The null hypothesis is that at the conclusion of the study there will be no differences in outcomes between the two groups.

All dental treatment, including dental hygiene and periodontal care, fillings, crowns and RPD fabrication will be provided by predoctoral dental students in the University of Kentucky College of Dentistry student clinics. Students treating the subjects will be supervised by licensed, technique-calibrated faculty specialists. Following the completion of dental treatment, enrolled subjects will be clinically re-evaluated by investigators at 6 months, and at annual intervals thereafter for 5 years following RPD delivery.

Study Overview

Status

Terminated

Conditions

Intervention / Treatment

Detailed Description

This study will investigate the use of highly esthetic, second and third generation multi-layer zirconia crown materials to restore removable partial denture abutment teeth. All performed treatment will be the standard of care and to the usual and customary standards used in United states dental clinics for crown and RPD procedures. Treatment subjects will have RPD abutment teeth restored with either Noritake Katana STML (anterior teeth) or HTML (premolars and molars) zirconia crowns, and periodically evaluated for 60 months following RPD delivery. Outcomes will be compared to a similarly treated control group restored with metal, metal-ceramic, or a combination of metal and metal-ceramic crowns.

Following informed consent, subjects will be randomly assigned using an internet program (https://www.randomizer.org/) to either a treatment (zirconia abutment tooth crown) or control (metal or metal-ceramic abutment tooth crown) group. Using information from the oral examination, articulated diagnostic casts will be evaluated , the RPD design confirmed, and the need for a crown on one or more abutment teeth verified. Enrolled subjects will be given oral hygiene instruction at the beginning of the study. They will also be instructed to brush their teeth twice daily using an OTC fluoride dentifrice of their choice. They will also be asked to use a 0.05% NaF oral rinse for 1 minute daily.

Abutment teeth must be in function with the opposing arch and vital at the beginning of the study. Vitality will be be determined using a synthesis of history, percussion, palpation and pulp testing. Pulp tests will be conducted using cold and an EPT, and the facial, lingual and occlusal (incisal) surfaces of all abutment teeth will be tested for responsiveness. If abutment tooth vitality is confirmed, teeth requiring surveyed crowns will be prepared and restored using standardized clinical and laboratory guidelines.

Abutment teeth restored with metal and zirconia crowns will be prepared and restored using the following clinical and laboratory guidelines. The margin will be a circumferential chamfer prepared to a depth of 0.5 mm with a rounded internal line angle and a 90° cavosurface exit angle. Margin height will be at or slightly coronal to the free gingival margin where possible. Axial surfaces will be prepared with a total occlusal convergence of >6° but not to exceed 20°. Incisal and facial surfaces will be reduced 0.7-1.0 mm. Functional surfaces will be reduced to 1.0 mm of opposing tooth clearance with the exception of under rest seats, where opposing tooth clearance will be 2.0 mm. At completion, the prepared tooth should have a height to base ratio of 0.4. If inadequate retention and resistance form is identified following preparation of axial walls, supplementary grooves will be added, the number and location of which are at the discretion of the investigator. Final impressions will be made using PVS in a custom tray (Extrude) and poured in type V dental stone (Jadestone). Following fabrication, the working cast will be articulated, tripoded, and the die(s) sectioned, trimmed and scanned (3Shape D2000 laboratory scanner or equivalent). The crown(s) will be waxed to full contour. Rest seats, undercuts and guide planes will then be developed in wax. Once the waxup has been surveyed and finalized, it will be secured to the scanning platform and a new scan performed with the waxup in place. The data file with the die scan will be merged with the file that contains the waxup. The merged file will then be transmitted to a designated production facility where the zirconia crown(s) will be milled. Canines will be milled using Noritake Katana STML zirconia and premolars and molars will be milled using Noritake Katana HTML zirconia. Once the crown(s) are returned and the margins, contacts, occlusion and contours clinically verified, they will be luted using a self-adhesive resin-based cement (RelyX Unicem 2).

Porcelain-fused-to-metal (PFM) crowns will be prepared and restored using a standard protocol utilizing the following guidelines. Posterior crowns will have metal occlusal surfaces with the porcelain-metal junction on the occlusal surface at half the distance between the central groove and the buccal cusp tip. Mesial, distal and lingual surfaces will be in metal, and the crown will have a disappearing metal margin on the facial surface. The facial preparation from mesiofacial to distofacial line angles will be a heavy chamfer or modified shoulder 1.0-1.2 mm in depth with a rounded internal line angle and a 90° cavosurface exit angle. Mesial, distal and lingual chamfer margins will be prepared to a horizontal depth of 0.5 mm. Facial margin height will be at or slightly apical to the free gingival margin. Mesial, distal and lingual margin height will be at or slightly coronal to the free gingival margin if possible. Functional surfaces will be prepared with opposing tooth clearance of 1.5 mm with the exception of under rest seats where opposing tooth clearance will be 2.0 mm. Nonfunctional cusp reduction will be 1.0 mm. Final impressions will be made using PVS (Extrude) in a custom tray and poured in type V dental stone (Jadestone). Following working cast fabrication it will be articulated, tripoded, and the die(s) prepared for conventional laboratory crown fabrication. Conventional (all-metal and PFM) surveyed crowns will be fabricated using noble and high-noble casting alloys and PFM crowns will use feldspathic porcelain as a veneering ceramic. Once the crown(s) are returned and the margins, contacts, occlusion and contours clinically verified, they will be luted using a self-adhesive resin-based cement (RelyX Unicem 2).

Qualifying RPD designs may be Kennedy class I-IV with up to two modification spaces, and will be designed using a standardized protocol. Maxillary major connectors may consist of a complete palatal plate, modified palatal plate, anterior-posterior palatal strap or palatal strap. Mandibular major connectors will consist of either a lingual plate or a lingual bar. Frameworks will be fabricated from nickel-chrome alloy (Ticonium), the denture bases acrylic resin (Lucitone 199), and artificial teeth will be DENTSPLY Trubyte IPN Portrait. To meet the definition of an RPD abutment tooth it must host a direct retainer consisting of an occlusal or cingulum rest, a proximal plate and a retentive clasp. Reciprocation must be provided in the form of a plate, reciprocating clasp or minor connector and rest. The plan for occlusion will be based upon the number and distribution of remaining natural teeth. If an arch opposing the RPD is edentulous and restored by a removable complete denture, then natural and artificial teeth will be arranged in bilateral balance. If anterior guidance is present on natural teeth in both arches it will be preserved so that artificial RPD teeth contact opposing teeth in maximum intercuspation only.

Clinical assessments, procedures and annual examinations will be performed in the University of Kentucky College of Dentistry second, third, and fourth floor student clinics. Clinical procedures will be performed by third and fourth year dental students, and clinical supervision for these procedures will be provided by licensed, calibrated investigators.

Study Type

Interventional

Enrollment (Actual)

1

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Kentucky
      • Lexington, Kentucky, United States, 40536-0297
        • University of Kentucky College of Dentistry

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

25 years to 70 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Partially edentulous and treatment planned for an RPD
  • Requires at least 1 surveyed crown on an abutment tooth
  • Abutment teeth and RPD in function with opposing arch
  • Abutment teeth vital at time of study enrollment
  • English literacy, cognitively capable of understanding study and consent documents
  • Cognitively and functionally capable of performing prosthesis and oral self-care

Exclusion Criteria:

  • Any chronic or degenerative condition which impairs consent capability
  • Any cognitive or motor condition which impairs ability to follow instructions or perform oral self-care
  • Healthy enough to tolerate planned dental procedures without premedication
  • Chronic infectious disease
  • COPD
  • Renal insufficiency
  • Autoimmune or chronic inflammatory disorders
  • Unstable asthma or diabetes
  • Unstable hypertension

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Full-contour monolithic Zirconia crowns
If participants assigned to this arm are in need of surveyed crowns on RPD abutment teeth they will be fabricated from multi-layered monolithic zirconia
Device: Full-contour monolithic zirconia abutment crowns
Subjects with RPD abutment teeth that require surveyed crowns will have them fabricated from monolithic multi-layered zirconia
Other: Conventional abutment crowns
If participants assigned to this arm are in need of surveyed crowns on RPD abutment teeth they will be fabricated from type III gold or high-noble metal veneered with feldspathic porcelain
Device: Conventional abutment crowns
Subjects with RPD abutment teeth that require surveyed crowns will have them fabricated from noble or high noble metals, veneered with feldspathic porcelain

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Need to Replace Crown on RPD Abutment Tooth
Time Frame: 60 months
This is a collective measure reporting need to replace an abutment tooth crown for any reason. This includes repeated adhesive failure at crown interface due to inadequate retention/resistance form in the abutment tooth preparation, catastrophic fracture of monolithic or veneering crown ceramic necessitating crown replacement, primary or secondary caries involving crowned abutment tooth necessitating crown replacement
60 months
RPD Abutment Tooth Loss
Time Frame: 60 months
Loss of any RPD abutment tooth for any reason whether crowned or otherwise.
60 months
RPD Failure
Time Frame: 60 months
Any technical or biologic complication resulting in loss of service of RPD. This includes loss of RPD as well as dissatisfaction and nonacceptance
60 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Tooth Loss
Time Frame: 60 months
Loss of any nonabutment tooth in either arch for any reason
60 months
Caries
Time Frame: 60 months
Dental caries involving any tooth in either arch
60 months
Periodontal Disease
Time Frame: 60 months
Change in clinical attachment level involving any tooth in either arch compared to baseline presentation.
60 months
Periodontal Disease
Time Frame: 60 months
Increase or decrease in mobility involving any tooth in either arch compared to baseline presentation.
60 months
Periodontal Disease
Time Frame: 60 months
Onset of fremitus involving any tooth in either arch relative to baseline presentation.
60 months
Periodontal Disease
Time Frame: 60 months
Change in furcation classification involving any molar in either arch relative to baseline presentation..
60 months
Periodontal Disease
Time Frame: 60 months
Change in overall score for bleeding index compared to baseline presentation.
60 months
Periodontal Disease
Time Frame: 60 months
Change in overall score for plaque index compared to baseline presentation.
60 months
Abutment Tooth Vitality
Time Frame: 60 months
Loss of vitality of any abutment tooth, crowned or otherwise
60 months
Patient Satisfaction and Quality of Life
Time Frame: 60 months
Change in patient satisfaction and quality of life, measured using the OHIP-14 questionnaire
60 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hiroko Nagaoka

Investigators

  • Principal Investigator: Vaughan Hoefler, DDS, MBA, University of Kentucky

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 1, 2017

Primary Completion (Actual)

November 30, 2019

Study Completion (Actual)

November 30, 2019

Study Registration Dates

First Submitted

September 11, 2017

First Submitted That Met QC Criteria

September 13, 2017

First Posted (Actual)

September 14, 2017

Study Record Updates

Last Update Posted (Actual)

March 13, 2020

Last Update Submitted That Met QC Criteria

March 2, 2020

Last Verified

March 1, 2020

More Information

Terms related to this study

Other Study ID Numbers

  • 17-0511-F1V

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

IPD Plan Description

There is not a plan to make IPD available

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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