2026 Catalog: All Courses

Updates 2025 - Answers to Prosthodontics Specialty Panel Questions

1.   Compare and contrast the literature supporting traditional pressed fixed restorations vs milled and 3D printed fixed restorations.
•   First to address 3D-printed fixed restorations [crown & bridge]: 3D-printed fixed restorations are currently used primarily for provisional fixed restorations, although there are new methods becoming available to 3D-print ceramic restorations as well. With regard to provisional crown and bridge restorations, there is a systematic review and meta-analysis available from 2022 [Jain et. al., 2022, Polymers ] that reviewed and analyzed research done comparing 3D-printed provisionals to milled and conventional provisionals, and they concluded that, in general, while 3D-printed provisionals do have a few drawbacks, [i.e. color stability and water sorption], they have superior fracture strength and wear resistance. They concluded 3D-printed provisionals are a good clinical alternative to milled or traditional materials for provisionals.
With regard to 3D-printed zirconia crowns vs milled zirconia crowns, there are relatively new materials and technology to 3D-print zirconia crowns; there is systematic review and meta-analysis from 2024 [Alghauli et. al., 2024, Journal of Dentistry] that concluded that both 3D-printed and milled zirconia crowns had acceptable internal and marginal fit, both had the usual zirconia strength, but with 3D-printed crowns having superior esthetics; other studies showed 3D-printed zirconia crowns have a microscopically rougher surface than milled crowns, but otherwise both manufacturing techniques led to clinically acceptable crowns. These materials are new, however, and haven’t had as much time for longer-term studies or evaluation.
•   Now to compare pressed fixed restorations and milled fixed restorations: In general, both methods produce fixed restorations with clinically acceptable marginal adaptation and strength. Some studies find the marginal adaptation of milled crowns slightly superior to pressed, others found pressed superior to milled, but most studies find that both methods produce restorations that are within clinically acceptable limits of less than 120 microns as to marginal adaptation. In general, either way is clinically acceptable. [J Prosthet Dent 2023 Jan;129[1]34-39]. On a related note, a meta-analysis from 2021 found that marginal adaptation for all types of fixed restorations was better with digital scanning impressions than with traditional polyvinyl materials [but this would be dependent on both the quality of the prep and the skill of the person scanning]. [J Prosthet Dent 2021 Apr;125[4]603-610]

2.   Now that amalgam is being phased out, some providers are using Fuji glass ionomer as final restorations due to its ease and it can be placed in multiple teeth rather quickly during quadrant dentistry. However, in our practice, I notice this material washes out, and doesn’t seem to be a good long-term solution compared to traditional composite. What are other providers noticing? What are they doing in their practices?
•   I can’t speak to what other providers are noticing or doing, and I know they’re a great option for primary teeth, but I shouldn’t address the use of GI in primary teeth as that isn’t my area; with regard to the use of glass ionomers for definitive restorations on permanent teeth, I do use them in geriatric patients with poor oral hygiene and/or xerostomia, but this is more or less the only place I personally use them. As you stated, traditional glass ionomers have been limited in their use due to these shortcomings – less durability than composites, water adsorption, etc., so my personal preference would be to still use posterior composite materials [or amalgam, as long as we are able to…] instead of glass ionomer; but there are a number of studies that show that while glass ionomers do tend to wear more quickly than composites initially, over the long-term, the two exhibit similar wear. [Comped Contin Educ Dent 2021 Mar;42[Suppl 1]:6-9]. Moving forward, I have read about new products emerging that are termed “high-viscosity glass ionomers”, that use ultrasonic activation and/or radiant heat during placement to improve these limitations. Supposedly, these would be more durable as well as have better marginal adaptation and integrity over time. My personal preference of posterior restorative material in most situations is the same as it has been for many years – amalgam is generally my first choice, followed by a posterior packable composite, followed by a glass ionomer. As with all things in dentistry, though, I’m sure other clinicians have different preferences, and their choice would be dependent on the clinician’s skill, the particular clinical situation, and what they’re most comfortable with using.

3.   What strategies or workflows do you recommend for managing complex restorative or surgical cases in remote IHS clinics where resources and specialists may be limited?
•   I can’t speak to surgical cases, but with regard to restorative cases, simplifying treatment plans generally is equivalent to decreasing the number of questionable [or hopeless] teeth that are present, and decreasing the amount of restorative work needed on teeth with a guarded or better prognosis. Fewer teeth means a less complex restorative plan, one where we can focus our attention, time and resources on fewer key teeth to provide a better overall outcome. That does not mean to overdo extractions, but maybe in what appears to be a complex restorative case, be more judicious about which teeth will stay and which will be extracted. In focusing resources and time on more critical teeth [in other words, in trying to simplify treatment plans], there are a few principles that I try to follow as much of the time as possible:
i.   Try to avoid lower complete dentures if possible – even keeping 2 or 3 teeth, even if only for a few years, will be a few years less that a patient has to deal with a complete lower denture.
ii.   Try to keep opposing sets of teeth, if possible, to maintain the patient’s existing vertical dimension, and allow at least a degree of tooth-to-tooth contact.
iii.   Try to keep cornerstone teeth if possible, especially in the mandible – canines and 1st molars.
iv.   Begin with the end in mind. Try to visualize what the entire mouth will look like when a given treatment plan is formulated, and create that plan to be as simple as possible and still meet the patient’s needs.
v.   ATTRITION: For a specific example of a typical complex treatment plan, as I’m sure you are all aware, with many of our patients, there is a significant amount of attrition present, sometimes leaving just a few millimeters of tooth structure supragingivally. This is always a difficult situation, but depending on the overall state of the dentition otherwise, you might have a few options. In general, if at all possible, the best option is to keep the patient’s vertical dimension the same. When this is not possible, because there simply is no room for any restorations or prosthetics, your two main options would be 1] extractions of remaining maxillary teeth, and a complete upper denture opposing, ideally, an RPD keeping as many lower teeth as is feasible; or 2] an increase in vertical dimension. [Actually, both of these involve an increase in vertical dimension, but this is obviously more in the clinician’s control with a complete denture]. If the patient only has a few [no more than 2 or 3] sets of opposing teeth, i.e. most of the teeth are missing or unopposed, this is easier to restore than someone with a relatively full dentition. In patients with a sparse dentition, sometimes a crown on a cornerstone tooth, or a cusp-protecting amalgam or composite on these opposing teeth, can be used to increase the vertical dimension and provide space for other restorations and/or prosthetics; an increase of no more than 2-3 mm at the canines is generally safe and is not going to create problems for a patient.

In patients with a relatively full dentition with heavy attrition but otherwise in acceptable condition, there’s not much that can be done, as a full mouth fixed reconstruction is not an option for us. For those patients, there is often not much we can do other than provide an acrylic guard to minimize future attrition, have them return for regular periodic exams, and monitor and restore as needed traditionally for as long as possible, extracting when teeth become symptomatic or are no longer restorable.

1]   Know the key advantages to 3D printed crowns
2]   Learn the difference between pressed and milled restorations.
3]   Know when it is best to use traditional glass ionomers

Roger Oldroyd — Personal Description / Biography not available. For follow-up questions, please contact the speaker at Roger.Oldroyd@ihs.gov.

The speaker has no conflicts of interest to report.

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