Our July implant study club was graciously sponsored by Carol Sachs of Nobel Biocare. We had the pleasure of listening to Dr. Kyle Stanley. The following is a synopsis of his lecture.
Dr. Stanley is a USC Graduate and did a residency in Brazil, where he focused on implant dentistry and performed research with regards to the position of the anterior teeth and smile. He teaches with Dr. Pascal Magne at USC, who is one of his mentors and somebody that he works with in biomimetic dentistry. He lectures for Nobel Biocare. On a regular basis works with Dr. Sacha Jovanovic at UCLA. At the lecture he talked about new techniques including, 1) digital smile planning 2) abutment modification and 3) custom impression copings.
Dr. Stanley feels the biggest problem in implant dentistry today is; lack of planning and knowledge, and not beginning with the end in mind. His goal is to create a natural look and thinks of the face, lips, gums and teeth as a single unit that has to flow naturally. He is exceptionally critical of incisal edge position and that is the starting point when he designs a smile. The anterior display of the teeth at rest is very important, as well as the lip length, the age, race and sex of the patient. For instance, when treating a 30-year-old patient, he allows 3-10 mm of tooth to be shown, in a 70-year-old patient, it is about 0-0.5 mm of incisal edge of the maxillary centrals shown at rest. Women tend to have two times as much show of teeth as men and aging loses the elasticity in the upper lip so it sags more and you show less teeth. At the same time, the teeth become worn down and they become shorter.
At this time 4 mm of maxillary central incisor shown at rest is the new norm for a common esthetic look. He showed a lip lift technique by Dr. Perenack developed in 2005 which uses an external incision under the nose removing a small amount of tissue and then allowed the lip to be lifted superiorly. There is a scar with this technique and in 2011 the technique was modified and the incision was made through the nose and held up with a retention suture eliminating the scar. The planning of the esthetic lip length is crucial and is often overlooked when it comes to smile design. He likes to display about 2 mm of gingiva apical to the teeth while smiling and thinks this is ideal. With the incisal edge a little lower, he likes that to be 0.2 mm from the lower lip, so he came up with the 42.2 rule. The 42.2 rule summarizes the measurements above.
In talking about central incisor width, it is 78% ratio in younger patients and 87% ratio in older patients. This is because as the patient ages, they grind down the teeth and the teeth become shorter and thus the ratio becomes a higher percentage. When he looks at the dentogingival esthetics at the zenith of the lateral incisor teeth, he says that the doctors at UCLA like to have the laterals and centrals at the same height where USC likes the laterals lower than the centrals and slightly shorter, thus the gingival display design is different, he uses digital smile planning to evaluate this. He likes to take photos at rest, with a small smile, large smile, and calibrated photo with the calibrator showing mm so it could be used by the laboratory and a full face shot with good retractors so that the plane of occlusion could be identified by the dental laboratory. He likes to add composite with no bonding agents in it to the incisal length of teeth to see how patients will appreciate that and whether other friends and family would find their teeth to be to short or too long and then he just chips that off after the fact, but he does take photos with that in place.
He spent a significant amount of time talking about the new ASC (angle screw channel) from Nobel Biocare and how it works noting it is a three-piece design, that the screw holds the zirconia abutment in place to the titanium abutment. It is blue in color to understand which screws are used is important, and it is torqued to 35 Newton cm. He says that you can use the ASC on molar teeth with the screw axis coming forward if you cannot open too well as another option for a screw retained molar. This is a practice saver and it allows him to do an excellent job maintaining screw retained anterior teeth in areas where normally it would not be possible. There is about a 25 degree angle this will accommodate. Still when doing temporaries, he uses a straight chimney on the temporaries and has that come out the incisal edge if that is the way the implants were placed and then just covers that with composite, but when he does his final impressions, then he moves to the ASC and uses the screw retained crown in a more traditional lingual or palatal position.
He then talked about the Nobel Connect and Nobel Clinician viewer for the i-pad. This is something that we use in the office and we are well versed in using guided surgery techniques. Dr Stanley felt that the new workflow was to take an impression and then do an ideal wax up (beginning with the end in mind) and then do a CT scan. The CT and wax up together are scanned and that makes for a co-mingling of those through the Nobel Clinician software.
Then you are able to make a guide that is restorative driven, driven by the ideal position of the final teeth thus giving us the depth, angulation and position of the implant to optimize the restorative result. He uses guided surgery on a high percentage of his cases. The ideal gingival margin should be 3 mm below the CEJ of an adjacent tooth and that pretty much has stayed the same. He definitely is a big fan of doing screw retained crowns wherever possible to eliminate cement margins.
The next thing he talked about is abutment modification for his temporaries. He feels he must maintain the papilla and that titanium provisional abutments are much better than any other material when it comes to gingival contact, so he takes the straight titanium abutment and he takes the additional collar and polishes it off to keep the chimney narrow and no wider than the implant itself eliminating impingement at the abutment interface. He does not like the plastic temporary cylinders. He does take the abutments and narrows them with the implant interface and likes to have all his restorations emerging off the implant without widening or flaring the platform to keep the buccal gingiva from moving apical on the maxillary incisor teeth. He uses shade A1 opacifier on the abutments and you want 1.5 to 2 mm straight up, then taper until 1-2 mm in all titanium. He does not like the fat impression copings and he wants to use narrow impression copings on all of the impressions making sure to fabricate a custom impression coping that allows for the ability to transfer the full information to the lab and by having a custom impression coping, the lab knows they can’t create a crown that is any wider than what is given to them. They cannot modify that in any way because that ends up leading to buccal gingival creep in an apical direction if they do not maintain those guidelines, so again he is not a fan of fat impression copings, but of the narrow impression copings and custom modified by using the standard technique for making a custom impression copings. He does use cross polarized lights on teeth. Cross polarized lighting in photography allows the lab to understand where the mamelons and various portions of the teeth are and by doing that is just another adjunct.
In discussing cements he thinks the excess cement can cause inflammation plus residual pain. Excess cement is a risk factor if you have a depth of 1 mm or greater of attached gingiva surrounding an implant. You will always have cement, not sometimes, but always. Implants are not teeth and they do not have an attachment like teeth do, so do not treat them like teeth. One of the biggest problems with the cement retention is bacterial colonization and all cements are different. It turns out in all the studies that Temp-Bond original is the best cement to not allow bacterial colonization. The Temp-Bond Non-Eugenol does have a lot of colonization so do not use that one or a cement like Multi-Link again has a lot of colonization of bacteria in the studies that he quoted. So as far as decreasing the amount of bacteria, the Temp-Bond original was the best. Next, he talked about making a duplicate abutment with Teflon that you could then place in the crown and in so doing, you can get the excess cement out of that area and just have the minimal amount of cement that is present. By doing this, you end up with a much less likelihood of having cement pour out into the adjacent tissues. He talked about the strength of removing the crown from an abutment in the clinical lab and it turns out the Temp-Bond is the same as any of the others tested, so the strength is as good yet the bacterial colonization is much less. The other thing that he talked about which was radiographic evidence and again he showed that the Temp-Bond shows up as well as Flecks on x-rays, none of the others show up on radiographs so you would not be able to make a confirmation of whether there was anything left behind. So Temp-Bond is highly recommended to cement implant restorations.
He showed a case where a mom's tooth was lost coronally and using biomimetic dental techniques, they reduced it and sealed the dentin and then following this, took the daughter's 3rd molar that was recently extracted and went through a series of steps with the Cerec machine to mill the internal of the daughter's tooth to match the existing root structure of the mother's tooth, at which time it was bonded in place, so instead of having a crown restoration, she actually had the daughter's tooth bonded to her existing molar as a restorative aspect. He went on to show multiple cases with regards to the esthetic zone and periimplantitis and finished his discussion with some really interesting and well done cases. His lecture was very well received by the members of the study club.