March meeting Conejo/Simi Implant Study Club

We would like to thank Nobel Biocare for their generous sponsorship of speaker Steve Hurson for our March meeting of the Conejo Simi Implant Study Club. Steve is a mechanical engineer by education who graduated from Cal Poly San Louis Obispo and has over 30 years of experience in the implant field. 

Mr. Hurson brought to us knowledge that he has accumulated from a long and industrious career at Nobel Biocare, spearheading the science behind the product line. His topic today was to inform us on how we can increase long term success by understanding the importance of proper screw preload, properly matched components and an occlusal scheme that will not deteriorate the system.

The original implants were all CP 1 (commercially pure grade).  Now the implants are CP 4.  Large diameter fixtures have a CPA value of 680 and all the other have a CPA 0f 750.  The manufacturer starts with a large bar that is cold worked into a smaller and smaller size.  This creates a work hardened bar stock.  As the oxygen and hydrogen and nitrogen levels go up the bar gets stronger.  There will also be trace amounts of iron in the implants. Some other companies use annealing to create their bar stock.

You can never overstretch a prosthetic screw, this is a myth. It will break before it stretches. You can’t make it too tight.  Steve described the preload of a screw to a stiff spring, like an old garage spring, we try to tighten it to 75% of its induced tension of yield. Today’s springs can be tightened 3 x tighter due to the stronger material used as compared to 25 years ago.   A problem with Ti screws in Ti implants is the galling of the surfaces as they rub against each other. Each time the screw is tightened it galls more and weakens the screw. This led Nobel to develop Torqtite coated screws. Each tightening leads to the small deposit of material and the screw can be tightened more. This coating lasts for  up to five tightenings before the coating wears off.

Screw loosening many times relates to poor management of occlusal forces.  The longer the tooth the more negative impact the horizontal forces will have on the screw system.  Best results will come from loading implants on their long axis in the posterior jaw, even if this requires the use of shorter implants to achieve the proper position.  Angled implants will place detrimental horizontal forces on the screw system.  As a side note, this does not relate to all on four cases since this load is held by the framework and dispersed over all the implants.  It is important to note that aftermarket screws do not have the high preload which will lead to a rocking motion and screw failure.  The tribe connection has a longer screw and tube that goes 4mm into the implant so it is less likely to rock.  The conical connection is even better as it has a 12-degree taper that stretches the implant wall and hermetically seals the micro gap.  These connections are all tested at over 5 million cycles with torqtite screws.  Overall, screw loosening can be attributed to occlusal overload, lack of screw preload and misfit components.

He advised all the attendees to purchase a 10x loupe so they can evaluate the lab work prior to delivery. Always wash all the component with soap and water and rinse in saline when they come from the lab, even sterilize if you can.  Do not use peridex as it will cause the periodontal tissues not to adhere to the abutment surface.  Furthermore, do not allow the lab to glass bead or grit blast the component.  It will create high points that can eventually lead to loosening.  The but joint is the best connection to the implant for multiple units as it sits passively on the shoulder of the implant.  It is even better to use multiunit abutments and move the micro gap further from the bone level, especially with the conical connections that can be hermetically sealed.  Additionally he advised against probing around implants, as the hemidesmisomal seal is broken each time and contaminated.  This attachment is much different than the bone implant level that consists of a 100 angstrom protein layer that the bone adheres to.

Steve then spent time discussing the soft tissue seal around dental implants and how important it is for good bone health and the prevention of perimplantitis.  He reviewed the role of the hemidesmosmal attachment that occurs. There are three materials that soft tissue will adhere to: Titanium, Zirconia, and PEET.  It will not adhere to gold.  This means that some sort of abutment is needed to provide the best seal. Try to eliminate anything that would prevent cell adherence to the restorative components.  So make sure the components are cleaned with soap and water and rinsed with saline. Sterilize if possible.  Do not use peridex as a cleaner for final abutments of temporary abutments as it will inhibit cell adhesion.  A mirror finish is no better than a machined surface in this regard.  He is not an advocate of probing around implants as he feels this leads to inoculation of the area with bacteria. 

I hope this information helps to build a better understanding of osseointergrated implants.

Changes in Anesthesia Consents for Minors

As you may be aware, many new laws have become effective as of the 1^st of the year.  One that will have an effect on our practice is A.B.2235, otherwise referred to as Caleb’s Law. It is directed at dental anesthesia of minors (considered anyone 18 years or younger).

The first part of this law will require the following language be added to our consent forms:

‘’The administration and monitoring of general anesthesia may vary depending on the type of procedure, the type of practitioner, the age and health of the patient and the setting in which anesthesia is provided. Risks may vary with each specific situation.  You are encouraged to explore all the options available for your child’s anesthesia for his or her dental treatment, and consult with your dentist or pediatrician as needed.”

Our office is particularly well positioned to handle the changes in three ways:

First, for patients over eighteen we can provide the same, safe, operator-anesthetist treatment that we have in the past and can modify the anesthesia for younger patients. 

Second, we have an AAAHC accredited and Medicare deemed (the highest level for ambulatory facilities) surgical center adjacent to our office. This is staffed by many of the finest physician anesthesiologists in the community. It provides an excellent option for monitored anesthesia care in a non-threatening environment for patients who are minors.

Third, we continue our long history of working at Los Robles Regional Medical Center where patients are able to have their procedures performed in specific situations.

For 42 years our office has had a strong relationship with the medical community and Los Robles Regional Medical Center. We feel very strongly about the long history of safety in oral and maxillofacial surgery and pediatric dentistry with the Operator-Anesthetist model.  The Conejo and Simi Valleys and other surrounding areas have many fine practitioners who have been providing safe and comfortable anesthesia to minors for decades. As we start the New Year we are positioned to continue to provide excellent service to our patients.

Year End Study Club Meeting 2016

For our year-end implant study club, commemorating 25 years of serving our dental community, we had  the pleasure of hearing a lecture from Dr. Sanda Moldovan. She did a great job holding the interests of the attendees as they enjoyed the fine food at the Four Seasons Hotel.

She began by talking about hygiene around implants.  Probing around implants has been controversial but the studies quoted showed that probing, especially bleeding on probing, was a useful tool to help diagnose perimplant mucositis which is the precursor to perimplantitis.  Delicate probing is the key to understanding that implants do not have the same biological attachment as natural teeth.  While flossing is important, Dr. Moldovan felt the use of oral irrigators has shown to be much more effective in disrupting the biofilm, especially around complex implant restorations that are difficult to negotiate.  She also encourage the use of chewable probiotics to help disrupt the oral flora and diminish the bacteria associated with periodontal and perimplant disease.

Breaking up the Biofilm is very important to overall oral health.  Using electric toothbrushes and oral irrigators was cited as the most effective choice around implants.  Studies have shown that patients on 3-6 month hygiene schedules decreased the failure rate to 90% and those patients that were on a one year or less recall schedule only decreased the failure rate by 60%.  With recommended maintenance intervals ranging from 4 weeks to 6 months depending on the patient., Dr. Moldovan thought is was very important to have base line records consisting of photos, radiographs and probing depths at the time of prosthetic delivery.   Hygienist spending significant time on education was also very important to creating patient awareness of the importance of home care.

For the remainder of the lecture Dr. Moldovan spoke about the importance of nutrients as they related to surgical healing and periodontal health.   She greatly favors a much more in depth health history that looks at diet, life style and supplements in addition to medical information.   For example, high Vitamin D levels are associated with less gingival bleeding, while low levels were seen in hypertension, osteoporosis, heart problems and more frequent colds and flus.  Furthermore, patients taking large amount of fish oils were likely to have more bleeding.  Vitamin C is very important, decreased bleeding and increased tissue health.  She also covered many other supplements and their roles in healing.

In summary, patient education and the right tools for hygiene should be coupled with a diet low in processed foods and high in the right supplements to ensure a more successful outcome in implant patients.  We would like to thank Dr. Sanda Moldovan for her insight and expertise. 

September Implant Study Club

We thank the Zimmer Corporation for sponsoring Terri Oto CTBS as our speaker for the September Study Club.

In the past, we have had the pleasure of having Terri present to our study club and her lecture was very well received. The following is a synopsis of her most recent lecture, “Technology of Graft Materials.”

Tissue banks are highly regulated government approved organizations and there are over 500 registered by the FDA at this time. Each company strives to maintain a strict level of quality control to remove high-risk donors and ensure safe tissue handling procedures. This high level of oversight is needed to ensure the quality of tissues available and to prevent the possible transmission of diseases. Her products through Zimmer are CE approved for European use and are recognized by the governments of 46 countries. They utilize an advanced tissue handling process that has been in use since 1971 to ensure over forty-five years of usage and five million implant cases with no cases of disease transmission. 

When choosing graft material is important to note that not all graft materials are the same even if they originate from the same source. This can be attributed to the variety of processing and packaging differences for each company. In general, there are four types of grafts to choose from. The first type of graft is an autograft which is an autogenous graft taken from a different site on the same individual. Next is an allograft which is a graft from the same species but not the same individual. These can be treated to become mineralized, demineralized or turned into a putty or paste. A great example of this type of graft is Zimmer Puros. The third type of graft available for use is a xenograft, which is a graft from a different but compatible species. Such grafts are often equine, bovine or porcine. One of the most well-known and well-documented xenografts is bovine graft, Bio-Oss. Finally, there are a variety of synthetic grafts available, most notably Alpha TCP, Beta TCP, HA, Biologics and Calcium Sulphate. Each of these graft types will have different healing and handling characteristics. Terri stressed the importance of picking the correct product for your specific application.

A good graft should have several important characteristics. First it should present outstanding and consistent clinical performance. Second it must have good handling characteristics and third, it must have surface characteristics that mimic natural bone. Finally, it is imperative that the graft shows good collagen integrity.

The tutoplast procedure used by Zimmer for the Puros product line takes 39 days to complete.  There are other companies whose process is done in 5 days.  The reason that the Tutoplast process takes so long is that they are trying to be as gentle as possible with the bone in order to retain its most important characteristics. Antigens are removed, pathogens are inactivated, preservation of the tissues is ensured and inactivation of bacterial and viral elements is confirmed to maintain a 5 year shelf life.

When it comes to Puross, mineralized bone is more effective than demineralized.  The .25 to 1 mm chips are the most advantageous sizes.  Cancellous bone is best for sites that you plan on reentering within 3 months such as extraction sites. The Cortical chips are more advantageous in sites that you will allow to heal longer as you would do with sinus grafts, as well as a large particle size such as 1 -2 mm. It was stressed that the bone product you choose should be based on reentry time to the area. 

The discussion continued with information on MinerOss and RegenerOss, as well as the company Life Net, who produces the bone products for Salvin, Straumann, Creoss and others.  They use a much shorter treatment process that involves sonication and centrifugation.  RegenerOss, has a very small particle size, and large surface area.  This makes it ideal for small defects such as perio furcation areas or voids adjacent to immediate implant placements

In regards to xenographs, Bio-Oss has long been touted for its excellent track record and consistency. Bio-Oss is sintered Bovine bone, which undergoes a high heat process that renders the bone a virtual ceramic. It acts more like a non-resorbable material in which the patient’s bone will form around it but not replace it.   It is especially useful for the maintenance of ridge volume in areas where future implants are not likely to be placed.  Again, Bio-Oss has a tremendous long-term track record.   Studies have shown the product present 9 and 14 years after placement with little to no change.

In closing, any graft should show the properties of attraction, adhesion and proliferation. When dealing with products the clinician should remember to not over-pack with excessive force in order to allow space for proper bone regeneration. It is also important to keep in mind the reentry time and clinical reasons for the graft. In our clinical experience, the better the vascular bed, the better the end result. 

Complications in Implant Dentistry

Case # 18   “My Implant Crown Never Felt Tight Like the Others”

Patient has a tissue level Straumann implant that is placed and allowed to integrate for 8 weeks. Impressions are made for a screw retained crown. The crown is delivered by an exceptionally skilled and experienced referral and torqued to 32 N/cm.  Shortly after this time the patient notes some movement in the crown; having other implants he questions this.  The abutment screw is retorqued; it is tight but still has some side to side movement, although almost clinically unperceivable. There was no pain on torquing the screw.  He lives with this for a year and notes it is slowly getting more mobility.

He presents to our office for evaluation.  First step is PA radiograph and CBCT that look fine.  Next is clinical exam and there is a rotational movement from left to right very minimally when the crown is grasped between the fingers.  It is barely perceivable but is present. On percussion the crown sounds solid

Diagnosis would include implant loosing integration.  Loose abutment screw and or loose crown.  Each interface must be checked systematically.  Since this is a screw retained crown that eliminates the need for drilling through the crown to access the prosthetic screw to remove it. It also eliminates the possibility of the cement union failing.  Although on a side note for the future there are many lab techniques using milled restorations that are advocating cementation of a crown to an abutment to create a screw retained restoration, only time will tell if this interface will weaken in some cases. In this case it was a cast UCLA type abutment.

The composite was removed a small cotton pellet was removed and the screw was reversed.  The screw was very tight and required a torque wrench to counter torque.  It caused no pain or distress to the patient when this was done. The area was irrigated after the crown was removed; a small amount of metal particulate consistent with a grinding movement of the crown was evident in the implant body.

To test the implant it was percussed and sounded solid an implant mount was placed and the implant was torqued and counter torqued with no pain or movement...  It was determined the implant was solid.  There was some debris in the implant consistent with the friction from abutment mobility.  

So next the internal integrity of the implant was tested to make sure the abutment had not degraded the internal connection. This was done by the placement of a transfer type impression coping it was place and tightened and attempts were made to rotate it. There was no movement.  This confirmed the implant internal connection was not damaged or rounded by the crown movement.  So continuing in a bottom to top analysis. The abutment was tested.

The abutment was tested by placing the screw retained crown on a brand new implant analog.  The model and original analog was not used since these sometimes become accidently modified in the lab setting.  It was noted that the crown ucla abutment did not fit flush to the implant analog.  There was a gap caused by a small hang up on the buccal where the porcelain extended to the metal junction. When the crown was placed on the analog mounted in the model as supplied by the lab it sat flush.   This was removed carefully under magnification incrementally until the crown fit snuggly on the new implant analog.  At this time the restoration was transferred to the mouth and fit snuggly with no rotational mobility.  A new abutment screw was placed and torqued to 32 N/cm, contacts and occlusion were tested Teflon tape and composite were used to seal the access hole.

A good example of a common problem that does occur in implant dentistry and why it is important to have a supply of impression copings and analogs as well as abutment screws always in stock so the this type of diagnosis can be made and corrected for the patient.

July 2015 Conejo/Simi Implant Study Club

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.

September 2014 Conejo/Simi Implant Study Club Meeting

We had the pleasure of attending the lecture that was sponsored by Sean Fisher of Zimmer Corporation.  The two featured speakers were Gregg Stebbins of Zimmer Trabecular Metal Technologies and Joanna Dorgan of Zimmer Dental. 

The lecture started with Mr. Stebbins talking about the metal Tantalum, which is the material that is behind their Zimmer Trabecular Metal Technology.  It is a porous biomaterial.  Originally, it was utilized by NASA in an effort to promote flying objects from getting into jet engines.  It was then owned by a company called Ultramet.  Ultramet was unsuccessful in creating this porous material for that specific utilization. In their research for other models to use Trabecular Metal in, they came across a biological model.  The microstructure of  Trabecular Metal is similar to coral.  There was significant research being done on utilization of coral as a allographic material and he felt there might be a place for Trabecular Metal to be used as an allograft.  There are 250 clinical papers backing up the success of this material and 15 years of proven utilization in orthopedic surgery, particularly in hip socket and joint restoration. 

The three things that make it a superior metal are the structure is similar to bone, in the function and physiology that it maintains.  It is a 99.9% pure metal.  It is not an alloy.  Tantalum is #73 on the periodic table and has a periodic weight of 180.95.  It is inert, noncorrosive to alloys, and when heated forms a 440 mcg average pore size dodecahedron that allows bone formation in the areas.  They coined this osseoincorporation, which is equal to bone ingrowth plus the addition of bone ongrowth, and it takes approximately 14 days for this to take effect.  It is a difficult procedure to make, done under high heat using a carbon core block that has been treated in a Tantalum gas chamber that deposits a fine layer of the Tantalum and takes 2-1/2 weeks for the material to adhere and approximately 6 weeks beyond that for fabrication of a dental implant.  

The dental implant that has been created was talked about by Joanna Dorgan of Zimmer Dental, the product brand manager. It is very similar to their Tapered Screw-Vent implants and it uses the press-fit internal connection that is common to all Tapered Screw-Vent products.  It has a trabecular metal band, a titanium upper, and a one piece welded at the apex of titanium.  The prosthetics are all common to a cross platform of Tapered Screw-Vent implants.  It comes in lengths of 10, 11.5 and 13 mm, and widths of 3.7, 4.1, 4.7 and 6 mm.  The advantage to the product is it has a final loading date of 2 weeks after insertion, which is twice as fast as the next competitor and about four times as fast as most other dental implant systems.  The drill sets used to place this are the exact same drill sets that we would consistently see with the Tapered Screw-Vent system from Zimmer Dental.  So it has a very high insertion torque and a higher surface area than the other implant models, thus giving it fine and rapid initial stability.