Cement Types

There are four types of dental cements: glass ionomer (GI) cements, resin-modified glass ionomer (RMGI) cements, resin cements, and self-etching resin cements. While the action "cementing" might sound permanent it is actually important that the dentist is able to remove the restoration if needed during the treatment of the patient. Yet, of course, it still must be strong enough to stay in the patients the mouth. Requirements other than retention that are considered include durability, seal and neatness (during application as well as preparation).Cements will never make up for lack of proper preparation of a dental restoration.

GI cement is primarily used in PFM and metallic restorations. It has thin film thickness, can cause some remineralization to the demineralized tooth structure due to fluoride release and retains moisture.

RMGI cement is very similar to GI cement, the only difference is that RMGI cement is not soluble in other oral fluids. While it has been used successfully on most types of restorations it is most commonly used in PFM, metallic restorations or any situation where moisture-control is problematic.

Resin cement creates a micro-mechanical bond to the natural tooth on one side and the restoration on the other. The preparation for resin cement includes pretreatment of the tooth with 37% phosphoric acid and a dentin bonding agent. All-ceramic restorations are mainly cemented with resin cement.

Self-etching resin cement does not need the pretreatment that resin cement needs. It is one of the most versatile being able to cement zirconia, lithium disilicate, metallic, all-ceramic, and PFM restoration materials.

Week 3

Yesterday I had my initial reference collection review with Dr. Kramer. It went very well. I found some sources that will really help with my final paper. My next task is to organize my sources into a chart using the date the article was written, what type of zirconia it mentions, how the intaglio surface is prepared, what intaglio primer is used, what cement type and brand is used, what methods of tooth surface preparation is used (total etch, selective etch, or self etch), and what the result is. The intaglio surface and primer are two layers that are essential to the overall success of the crown. If you think of the crown as different layers the zirconia would be on the top, then the intaglio surface, the intaglio primer, the cement, the primer for the natural tooth and finally the natural tooth on the bottom. Not only did we talk about my sources and next steps for my project, we also finalized my initial abstract. He had some great tips to help my abstract sound more professional. I will be continuing to search for sources to categorize. Stay tuned!

Chemistry and Dentistry

I chose Mr. Caniglia as my BASIS faculty supervisor because I took his organic chemistry capstone class this year. As I find out more about the "what" of dentistry I want to have Mr. Caniglia help me with figuring out the "why". For example I learned that zirconia and lithium disilicate undergo different crystalline structures based on what part of the crown-making process the crown is at. During the phase that the crown must be shaped zirconia and lithium disilicate take on different color and are more malleable, but after the final firing stage they loose that color and the crystalline structure becomes fully hardened. Mr. Caniglia and I are working on using my basic knowledge of organic and inorganic chemistry to help me understand the reason why this happens. Another topic of interest is in the properties that make porcelain, zirconia and lithium disilicate match the color and translucency of human teeth so well.  Check back for more updates! 

What are crowns?

When a tooth has decay, a filling is a technique that can reestablish the normal function and shape of the tooth. Materials used for fillings include gold, porcelain, a composite resin and an amalgam. If a filling can no longer salvage a tooth because the decay is too invasive, then a crown, also known as cap, is used. Cracked teeth are held together by crowns as well. Crowns are also utilized when a tooth is discolored or misshapen. Crowns are fit on top of the metal parts of root canal implants or whatever remains of the patient’s original tooth. Dental bridges are another way crowns are helpful. They anchor either side of a dental bridge that is meant to fill a gap made by a missing tooth. Here are a few different types.

Gold is one of the best materials for a crown because it is long lasting and durable, however it is easier to see in the mouth which deters some patients from choosing it.

Gold crown

Porcelain fused to metal (PFM) crowns are aesthetically pleasing, long-lasting, accommodate the shape of the tooth well and are inexpensive. Disadvantages to PFM crowns include the dark line that appears where the crown meets the tooth near the gum line and more of the original tooth needs to be removed to fit the crown. 

PFM crowns 

All-porcelain or all ceramic crowns do not show a dark line, match other teeth extremely well, are non-allergenic and can be performed in one appointment. Though, these crowns are fragile, cause teeth sensitivity, tricky to fit, need more of the original tooth reduced and are more expensive than PFM crowns. 

All-porcelain crowns

Zirconia crowns resemble natural teeth well, rarely are rejected by the mouth, are fairly durable and do not need as much of the original tooth removed to fit. 

Zirconia crowns

Lithium disilicate crowns have low fracture rates, resemble natural teeth well and are easily shaped.

Lithium disilicate crowns

Week 2

On Monday I met with Dr. Kramer and we went over the sources I have been using for my information on the six different crown materials. My new task is to find articles that specifically deal with cementing protocols for zirconia and lithium distillate crowns. To aid my research and enhance my understanding of what a research paper at this level reads like, Dr. Kramer gave me a sample paper on dental materials that a student wrote for his class along with a large packet of sources that I can sort through.  Tomorrow I am going to set up a dropbox so I can communicate with him easier as I start writing and come across certain sources that I think could be beneficial to my research. We set a goal for next Thursday to have an initial reference collection review, where we will share our narrowed down sources and talk about the sections in each that have relevant data to use. Dr. Kramer also gave me the number of a dentist who has a practice right down the street from Midwestern. This dentist owns a CAD/CAM that helps design the crowns right there in the office. This will be a great opportunity for me to shadow him to see the zirconia and lithium disilicate crowns being used first hand. I have had a great second week!

Introduction

WELCOME

Hello, my name is Sydney Miller and for my senior project I will be researching the optimal bonding protocol for zirconia and lithium disilicate crowns. My mentor is Dr. Robert Kramer, who is an assistant professor and preclinical leader at Midwestern University's College of Dental Medicine. I will be on campus Mondays, Wednesdays and Fridays each week. 

My first week was extremely exciting. On Monday, Dr. Kramer gave me a tour of Glendale Hall, which is the hub of the dental school and where I will spend most of my time. From the work stations, where the dental students practice their techniques on mannequins, to the laboratories, the facilities are amazing. I had the honor of meeting and chatting with some of Dr. Kramer's brilliant friendly colleagues throughout my tour as well. Finally the tour ended in his office and we talked about our plan for my project moving forward. He wanted me to bring in my materials and sources I had used for my background research so he could further narrow my broad topic of "dental crowns". When I came back Wednesday he explained that it is important to understand the chemistry, physical properties, manufacture and synthesis of different crown materials. My task was to compile that information for each of the following types of crowns: zirconia, lithium disilicate, porcelain fused to metal (PFM), gold, leucite reinforced and zirconia lithium silicate. While I am still working to gather information on each material, it has tremendously helped my level of comprehension when reading dental journals and research papers. Studying the different crown materials has also helped me find solid sources that will contribute to my final paper. 

I loved my first week at Midwestern. Interacting with Dr. Kramer inspires me to learn as much as I can about dentistry. Even though it is mostly reading dental journals with scientific language that at times goes over my head, I still enjoy every moment of it. 

Midwestern University-Glendale Campus