Several months ago an article came out in the news that linked composite fillings that contain BPA during childhood with social issues like depression, stress and anxiety. BPA or Bisphenol A is a chemical present in many plastic materials, and has been associated with numerous health issues, resulting in it’s removal from many products such as water bottles and baby bottles. One of the chemicals in composite filling materials is bisGMA and it is made from BPA. Last month’s issue of JADA included an article based on research that showed increased levels of BPA in both saliva and urine for a number of hours after the placement of composite fillings containing bisGMA.
In previous posts I have talked about the challenges we encounter with composites that extend interproximally. Pre-wedging the teeth and proper selection and placement of a matrix system are two critical steps for creating consistently tight contacts. Preparing the tooth with convenience form is a key component that allows us to see and trim and adjust the margins of the interproximal portion of the restoration. With all of these key pieces in place I was still struggling with shaping the occlusal portion of the marginal ridge to create the proper shape to the occlusal embrasure, and sometimes polishing the interproximal box margins.
Recently it dawned on me that I am wedging before I begin preparing the tooth to create an interproximal space, why not wedge after the tooth is filled to create the same space and facilitate the trimming and polishing phase. For the last few weeks I have been removing the separator ring, band and wedge after the prep is filled and the composite cured. Then repositioning the wedge before I begin trimming and polishing. this small step allows me vastly improved access for my mosquito diamond, the tip of a white stone and discs to perfect the shape of the interproximal contact, occlusal and gingival embrasure form and marginal interface. Similar to when we shape the interproximal of a provisional you do not want to polish or adjust the area that composes the contact, which was created by proper band placement and contour, but right up to it.
Cracked teeth have been traditionally treated by a process we call “containment”. The tooth is prepared so that restorative material will be around the tooth circumferentially and contain the cracked pieces, holding them together and preventing progression of the crack. The placement of a crown or onlay removes a significant amount of tooth structure and increases the risk of post operative pulpal death. Adhesive dentistry and composite materials can be used as an alternative because of their ability to reinforce the remaining tooth structure. Studies show that teeth with MOD preparations and restorations exhibit much lower cuspal flexure when the restoration was bonded into place using an acid-etch adhesive technique. This ability to hold the remaining cusps together and limit flexure can prevent the progression of a crack while still preserving tooth structure.
I am old enough that I learned amalgam as the go to operative material. In those days when we encountered deep decay we followed a process of applying calcium hydroxide to the deep areas of the prep and expected good results in the formation of a dentinal bridge and survival of the pulp. When we transitioned to composite products like Dycal(Calcium Hydroxide) and Copalite disappeared. For me it has felt like there has been a void in my ability to pulp cap in the instance of deep decay under a composite. Using glass ionomer or RMGI is probably the most accepted technique. The challenges I have run into are the set time of the materials and the limited bond strengths to dentin. Earlier this year Bisco dental released a new product designed for just this purpose. I have been using it ever since and finally feel like I have a pulp capping product I can use with confidence.
Post Operative sensitivity can be both a normal and abnormal sequela of placing a posterior composite. I make sure my patients are expecting some temperature sensitivity, and even tell them to be cautious the first time the have a cold drink after the anesthetic wears off. Beyond the mild pulpitis that can be induced during the preparation and placement of a posterior composite is the sensitivity that lingers. When I speak with dentists who have a question about sensitivity, the first thing I ask them to do is recount heir adhesive technique with me. The reason is that almost all lingering issues can be tagged on a piece of the adhesive process.
Key to the long-term success of a posterior composite is the marginal seal and integrity. The margins are the area most likely to break down, evidenced by leakage, staining or recurrent decay. Interproximal margins are perhaps more subject to these issues than the margins we see easily on the occlusal surface. So how do we assure proper seal that will last over time. In the prior post of posterior composites I mentioned convenience form. I think this is a critical step in marginal integrity. Having adequate convenience form allows us to see, feel and finish the margins interproximally. In this way we can be certain the day of placement we have created sealed the margins.
One of the largest complaints I hear about posterior composites is in our ability to predictably create tight interproximal contacts. I often joke that when I am ready I take the floss from my assistant, place it in the occlusal embrasure, turn my head and say a prayer before I try and pop it through to the gingival embrasure. Over the years it has been the combination of multiple steps that have helped me overcome this technique challenge. The first thing I do is pre-wedge any tooth that will be prepared with an interproximal box. This step creates adequate tooth separation to overcome the thickness of the band.
One of the most critical factors in the success of posterior composites is adequate isolation. Our ability to achieve acceptable bond strengths and prevent marginal breakdown and leakage are dependent on it. Blood and saliva are the enemy during any adhesive procedure. There are numerous options that all allow us to achieve proper isolation. The tried and true is still placing a rubber dam, and even as I type this I know people are cringing at the thought of it. With practice and proper technique rubber dam placement can become easy and efficient. In addition there is also the option of utilizing a split dam technique. In this approach one large slit is created that goes over multiple teeth and is anchored by a clamp on the most posterior tooth and flossed between the anterior abutment teeth.
By far one of the most common procedures I do in a general practice is a posterior class two or class three. It is also one of the most popular topics to discuss at dental meetings or when a group of dentists gathers together. Why do we focus so on this one type of restoration, with all of the services we offer. Part of the answer is the frequency with which we offer this service. Another reason is that given the frequency we expect a pattern of predictability to develop, the results to be consistent and this process to become less stressful over time.
If it is possible, and not to weird, to be in love with a matrix band, I am. Over the last month I have started to use the Composi-Tight 3D Clear sectional matrix from Garrison and I can not imagine going back to using anything else. I have been a fan of sectional matrix systems for many years, but all of them have had little nuances that had to be overcome clinically. One of these is that the shape of the metal sectional matrix bands does not curve around the buccal and lingual walls of the tooth. Getting the matrix to seal the buccal and lingual walls of the proximal box required a combination of curling it around the handle of a mirror and using the wings of the separator ring.