The Complete Workflow Guide for Multi Unit Abutment Treatments

The Complete Workflow Guide for Multi Unit Abutment Treatments image

Dr Ruben Gurie

Whether you’re talking bar retained dentures, overdenture implants, a direct to fixture implant, or multi unit dental implants there are a range of patient treatment options.

A good dental implant restoration will look, feel and act just like natural teeth. It will last for many years, prevent bone loss, and help to stabilise remaining teeth. A multi unit abutment or an overdenture treatment will also help to prevent premature facial ageing, and improve quality of life for your patients.

However, the reality is a multi unit implant abutment — while an excellent treatment option for some — is not appropriate for all patients.

“Implants are not for everybody,” says Ruben Gurie, an implantology specialist at Dentsply Sirona. “There are certainly indications where you have to tell the patient that you can’t place an implant and an alternative treatment is a preferred option.”

Gurie says proper patient assessment and selection is critical to achieve positive treatment outcomes. “You can’t just say let’s do full-mouth implants without thorough patient assessment,” he explains. “If you do a proper pre-clinical evaluation, you’ll have success.”

5 Step Patient Assessment for Multi Unit Abutment Treatments

Select the wrong patient for a multi implant restoration, and you could be looking at a catastrophic failure. That’s why dentists should adopt a five-step patient assessment process before accepting any patient for a multi unit implant abutment restoration treatment — whether that’s overdenture implants, a simple direct to fixture implant, or a more complex implant restoration.

Step 1: Extraoral examination

It all begins with an assessment of the patient’s overall general health. Lifestyle factors such as alcohol and tobacco use should be considered in the first place.

Excessive alcohol consumption can lead to changes in alveolar bone healing. This can negatively affect osseointegration and increase the risk of implant failure. While a patient’s alcohol usage may not eliminate them from treatment alone, it’s important to consider their drinking habits in the context of other health factors. For example, a heavy drinker who also suffers with diabetes may be a poor candidate for multi unit abutment treatments.

Smoking can also be an issue. Smoking is widely accepted to inhibit healing, and can damage delicate oral tissue. In fact, tobacco use may double the risk of implant failure. Again, assess a smoker’s eligibility for multi unit implant treatments in line with other general health factors discussed below.

Gurie says dentists should also be aware of any pre-existing health conditions that may negatively impact a patient’s case. He says patients with osteoporosis may also have problems with osseointegration.

Osseointegration refers to how bone growth responds to dental implants. Poor osseointegration could lead to structural and functional weaknesses in the connection between new bone and the implant. This can create insufficient anchoring around the implant, and cause catastrophic implant failure.

However, long bone decalcification present with osteoporosis has been shown to be only moderately linked with jaw decalcification. For this reason, patients with osteoporosis may not need to be automatically eliminated from multi unit implant treatments, including overdenture implants and a Hader Bar implant denture.

However, patients with osteoporosis should be carefully assessed to ensure no other extraoral or intraoral issues exist that would further increase the patient’s risk factor.

Patients on anticoagulation medications for heart disease and hypertension should also be carefully assessed. You may need to discuss any planned dental surgery with the patient’s cardiologist or primary doctor to get a clear picture of their suitability for potentially complex multi unit implant treatments.

Gurie says uncontrolled diabetes, the presence of sepsis or cancer, autoimmune diseases, or patients undergoing radiotherapy may also be poor candidates for multi unit implant treatments.

“As dentists, we need to do a thorough medical history assessment for every single patient, where they are undergoing a direct to fixture implant, a multi unit abutment, overdenture implants, or implant restoration,” Gurie explains. “This should never be overlooked.”

Step 2: General intraoral examination

Gurie says the next step is an intraoral examination. You’ll need to assess not only bone quality, but also consider the anatomy of the mouth, and where you would potentially place the multi unit implant abutment.

“When you’ve completed the pre-clinical extraoral evaluation, and have ticked the box that they are healthy to move forward, it’s time to look at the anatomy of the mouth,” he says. “In addition to assessing bone quality and precarious teeth, we must also identify whether we will be able to place the implants where we want to. If this is not possible, our treatment may be compromised.”

Assessing oral caries is a good starting point. This is a good opportunity to examine the health of remaining teeth, and determine whether any supplemental treatments will be required before moving onto an implant restoration. Evaluating oral caries is also a useful tool to help determine the patient’s general oral health and their awareness of proper oral hygiene practices.

The dentist should also check for signs of periodontitis. Patients with periodontitis may have an increased risk of developing peri-implantitis, which could inhibit bone support around the implant and lead to implant failure.

Swollen, puffy or tender gums can be a sign of periodontitis. Receding gums, bright red or purplish gums, pus between teeth and gums, loose teeth, and new spaces developing between teeth or a change in bite, can also indicate periodontitis.

Any infections in the alveolar bone should also be identified, treated and resolved before progressing with any implant treatment.

Step 3: Implant specific intraoral examination

Before moving onto radiology, dentists should pay close attention to the anatomy of the implant site or sites at this stage. This includes evaluating the anatomy of the implant site, and examining the health of the soft tissue and reviewing any aesthetic considerations at the implant site.

Examine the dimensions of the implant site, assess the condition of any surrounding teeth, and ensure there is at least 1.5mm of bone between the implant and adjacent tooth to stabilise the implant.

Periodontal probing under anesthesia can also be used at this point to assess and define the mucosa thickness at the implant site. A thin mucosa is another risk factor for implant failure, so should be considered along with other risk factors that may have been identified in the patient.

Any adjacent or surrounding teeth should also be carefully inspected for colour, health and the integrity of any existing restoration work. This is important for achieving both aesthetic value and stability at the implant site.

Step 4: Radiography assessment

At this point the patient should have passed general extraoral and intraoral examinations, and the implant site or sites should have been deemed appropriate to continue.

Now it’s time to explore further with a radiographic examination. This will assist to further assess the condition of any remaining teeth, and ensure bone height and width is sufficient for a stable implant. A radiographic examination will also help you to ensure the implants can be placed without causing damage to neighbouring structures.

“At this point you need to send the patient for a CBCT scan,” says Gurie. “This enables us to really look at the density of the bone, and see whether we need to augment. The CBCT scan will also show whether we can place the implants where we want to, or if our treatment may be compromised.”

CBCT (dental cone beam computed tomography) scans, offer several key benefits when it comes to assessing patients for multi unit dental implants, including overdenture implants and multi unit abutment treatments.

CBCT scans provide better image quality and accuracy. They enable dentists to examine areas as small as a single tooth root, and 3D functionality allows dentists to view the implant site from a range of angles to provide a much clearer picture of the patient’s suitability for the implant.

A cone beam CT scan also enables the dentist to assess both the bone and soft tissues in much more detail than a traditional X-ray. Again, this gives the dentist a much clearer picture of the patient’s overall oral health and how they are likely to respond to a dental implant.

CBCT scans are also easier on the patient than traditional X-rays. They deliver a lower dose of radiation, and a full-mouth scan can be completed in less than a minute.

Step 5: Virtual treatment planning

While CBCT scans give the dentist a very accurate and detailed picture of both bone structure and soft tissue health, virtual treatment planning software can take this a step further.

Gurie says Simplant is one software solution that can help dentists make the final decision on the patient’s suitability for implant treatment, and will ensure a high likelihood of success.

“Simplant gives the dentist the ability to virtually place the implant in the bone, so you know what to expect,” he says. “You’re giving yourself an in-depth look into the bone and the anatomy underneath the tissue in the mouth.”

Gurie says virtual treatment planning with Simplant will help to reveal any issues that may have been overlooked during other intraoral examinations, and identify any hidden problems that may disqualify the patient from multi unit implant treatments.

Prior to this kind of technology, dentists had to rely on two-dimensional X-rays to determine implant placement. This meant that dentists were only able to fully visualise the patient’s anatomy during the procedure, and surprises could occur that may compromise the success of the treatment plan.

Virtual treatment planning software like Simplant eliminates this problem by giving dentists the ability to virtually plan every step of the treatment — and potentially alter the treatment plan or switch to an alternative treatment prior to physically working on the patient.

Simplant will also create a custom surgical guide that is specifically designed to fit the anatomy of your patient. This vastly increases accuracy, which is important for a few reasons.

Mandibular nerves are avoided, and it’s much easier to protect the maxillary sinuses in the upper jaw. The surgical guide also dictates the implant angle, so you’ll be as close to certain as possible that the treatment will be successful before you even accept the patient.

3 Step Implant Workflow for Multi Unit Abutment

We can now proceed to the diagnostic denture, implant surgery and accuracy verification stages of the workflow. These processes require close collaboration with your dental lab and Avant Dental technicians will work with you to ensure each stage of the multi unit abutment or overdenture treatment workflow is completed with the precise accuracy that is required to achieve the best possible final treatment outcome.

Step 1: Diagnostic denture for multi unit abutment

Also known as a trial or transitional denture, the diagnostic denture is the critical next step in treatment planning for a multi unit implant abutment. It enables the dentist and patient to test a trial version of the permanent prosthesis to ensure both are satisfied with fit, function and aesthetics

Ruben Gurie, an implantology specialist at Dentsply Sirona, says that while some dentists can be tempted to skip this stage, they do so at the detriment of running into prosthetic complications during the restorative phase.

“Some dentists prefer to guesstimate where they are going to be placing the implants,” he says. “But even the most experienced implant dentists should not skip the diagnostic denture. Predictability in implant dentistry is very important, and the diagnostic denture is critical to ensure a more predictable outcome.”

That’s because a diagnostic denture essentially provides a test run of the final treatment outcome. The patient can spend some time — usually a month or two — developing a feel for the fit and function of the diagnostic denture, and can provide vital adjustment feedback to the dentist.

The diagnostic denture is also an important tool to help retrain muscles in the jaw to accept the restoration.

“If you’re dealing with a patient that has no teeth, and you want to throw implants in there and slam a fixed bridge on it, that patient is most possibly going to experience post restorative issues,” Gurie explains. “Being edentulous for a period of time changes the behaviour of the patient’s muscles and the TMJ joint . The natural harmony changes over time.

“Then all of a sudden you try to go straight into an implant prothesis and just expect the patient to adapt to it. You’re going from zero to hero and down to zero again in a very short time. We need to transition these patients with a diagnostic or transitional denture which paves the pathway in training the muscles of mastication into somewhat of a natural position.”

Critically, the diagnostic denture is also used to establish the most correct occlusion and centric relation of the upper and lower jaws. To achieve a successful treatment outcome, the dentist must create the perfect condition in the mouth. Without the correct occlusion, the final outcome will not be favourable.

Dentists should also be wary of using a patient’s existing denture as the diagnostic denture. This runs the risk of transferring existing inaccuracies to the new restoration. Rather, Avant Dental can work with you to manufacture a new, temporary transitional/ diagnostic denture to ascertain the precise dentate position and establish natural jaw relation .

“Establishing the correct tooth and natural bite positions are paramount to achieving a positive final treatment outcome,” says Gurie. “Once you have that sorted, everything is balanced and the muscles are fine, the patient should feel that they would be happy to keep the diagnostic denture if it was properly secured. That’s where we want to get to. We’re using the diagnostic denture to establish the occlusal plane of the teeth as well as the occlusal layout of the teeth on the jaw”.

Once you have reached that point, the diagnostic denture should be lined with scan dots and two CBCT scans should be taken. One scan will be of the patient with the diagnostic denture in their mouth, and the second will be a stand-alone scan of the diagnostic denture out of the mouth.

These scans are sent to the dental lab, where Avant technicians overlay the two images into the implant planning software typically called the dual scan technique to create a dual scan. This gives us a very clear picture of the patient’s mouth and bone structure in relation to his/her bite and will help us identify precisely where we are going to place the implants.

Step 2: Multi unit dental implants surgical guide

With final adjustments made to the diagnostic denture, the dentist and patient should now be happy to proceed to the surgical stage in the workflow. Your dental lab plays a key role in this too. At Avant, we work with the dentist to design and manufacture a surgical guide. This essentially acts as a template the dentist can use to determine the exact drilling position and depth for each implant.

To design the surgical guide, Avant technicians load the dual scan into our implant planning software system. At this point, we’ll also speak with the dentist about the implant system they are using, and any other components needed.

From here on, we’ll create a digital design of the implant plan, then consult with the dentist online to modify the design in real time, talk through any potential problems, and ensure the implants are placed in the best possible position.

With the final design approved by the dentist, we’ll then 3D print the surgical guide. At Avant, we always recommend using a fully guided drilling template. However, some dentists do prefer to use a pilot guide.

Gurie explains there are some key differences between a fully guided and a pilot surgical guide. Both drilling templates set out the position of the drill holes for each implant. However, a fully guided template also features depth stoppers that guide the direction and exact depth of the drill.

“It takes a huge amount of concentration and focus to place an implant,” says Gurie. “It’s a really sharp and acute process, and can be very nerve wracking. With a fully guided system, the drill will automatically stop at a certain depth. So if you’re putting in an 8mm implant, the drill will stop at precisely that depth. You’re getting an ideal outcome in depth and placement.”

While fully guided surgical templates are recommended to ensure the best possible accuracy, Gurie says there are some instances in which a pilot surgical guide will be favoured by some dentists.

“Going freehand with a pilot guide is easier when you have enough bone, and enough nerve distance,” he explains. “But a pilot guide doesn’t have depth stoppers. When you’re drilling, all it is doing is giving you an indication of where the initial drill position is going to be. It will not stop the drill at the precise depth you want.”

Gurie says the decision to choose a fully guided or a pilot surgical guide may also come down to the implant system the dentist is using.

“Different implant systems have different osteotomy drill preparations,” he explains. “For example, some implant systems are fully guided so you only have one guide master sleeve and each drill has its own sleeve. There’s no need to change anything. However, other implant systems may have a master sleeve with drill keys, so as your drill gets larger the diameter changes. The drills may have depth stoppers, or they may not.

“It’s important to keep in mind that pilot drills are not fully guided, and you want to be very clear on whether the implant system you’re using is fully guided or not. If you are not using a fully guided implant system, then I would certainly recommend getting a fully guided surgical guide made. Accuracy is critical here, and even the slightest mistake could lead to a possible treatment compromise.”

Step 3: Accuracy verification for multi unit implant abutment

With the implants now successfully placed in the patient’s mouth, some dentists may choose to immediately load the implants. However, to do so, primary stability of 25+ must be achieved. Gurie says this can be possible with self-drilling implants that thread into the bone to increase stability, however the dentist should proceed with caution.

At Avant, we generally recommend against immediate loading in all but the simplest of cases. We find that allowing the patient time to heal typically improves osseointegration and achieves better stability. Depending on the implant system you use and the patient’s individual situation, healing time can be anywhere from six weeks right up to three to four months, and possibly more if GBR or GTR is performed.

Once the patient has had the appropriate healing time and sufficient stability has been achieved, it’s time to create models of the mouth and verify the accuracy of the implant placement. We do this with a verification or accuracy jig.

The dentist takes a digital scan or makes an analog multi unit abutment impression of the patient’s mouth. At the lab, we’ll either 3D print the scan or make a plaster mould of the analog impression. As with most aspects of digital dentistry, we find that digital scans tend to deliver better accuracy than analog impressions, and the future of dentistry is certainly going down the digital path.

The resulting model will provide a baseline for us to design the final, permanent prosthesis, so accuracy is paramount. However, any slight inaccuracy of the oral scan or impression will create inaccuracies in the model. So before we spend thousands of dollars designing and manufacturing the permanent prosthesis, we will make a verification or accuracy jig to verify the scan or multi unit abutment impression — and therefore the model.

The verification/accuracy jig is essentially a series of cylinders that are joined by a resin bar. The dentist connects each cylinder to the corresponding implant and x-rays the patient to determine the accuracy of the fit.

If inaccuracies are present, the dentist can cut the resin bar and rejoin it in the mouth. The dentist must then take a new impression with the jig in the mouth. The position of that jig will then determine how we’ll design the final prosthesis.

Gurie emphasises the critical importance of accuracy at this stage. “We need to ensure that the scan or impression relates precisely to where those implants are actually placed — particularly if you’re taking analog impressions,” he says. “Any inaccuracies here can lead to treatment survival/failure and not success.”

At this point in the workflow, design and construction of the final, permanent prosthesis is ready to begin.

Summary of multi unit abutment workflow

When it comes to ensuring successful implant treatment outcomes, the importance of proper patient assessment and selection cannot be understated. There are a range of general health and oral health issues that can put patients at serious risk of implant failure, along with mouth anatomy issues that may inhibit the dentist’s ability to execute an appropriate treatment plan.

Patient assessment should begin with a thorough medical history. Any underlying systemic health issues such as uncontrolled diabetes, heart disease, hypertension, autoimmune disease, osteoporosis and cancer should be carefully reviewed.

Lifestyle factors such as smoking and excessive alcohol use can also increase risk of implant failure, and should be considered as part of the patient’s overall health profile. Patients on anticoagulation medications or under-going radiation therapy may also be better suited to an alternative treatment.

If the patient is in good overall health, the dentist can move onto an intraoral exam. Periodontitis should be identified as a potential determining factor as to whether the patient is a good candidate for a multi unit implant treatment, and the patient should be carefully examined for alveolar bone infections.

The dentist will also need to assess the implant sites. Evaluate the anatomy of the implant site, examine the health of the soft tissue, and review any aesthetic considerations at the implant site to determine if implant treatment is the best path forward.

Then it’s onto a radiography assessment with a CBCT scan. This will assist in the assessment of the condition of remaining teeth, underlying bone structure, and tissue health. Virtual treatment planning software such as Simplant can also be used at this point to accurately plan implant placement and identify any hidden issues that may compromise the implant treatment.

If the patient passes all five assessment stages, then they are likely to be an excellent candidate for a multi-unit implant treatment with a high likelihood of achieving a successful treatment outcome.

By selecting only patients with a high likelihood of success, the dentist is proactively limiting potential treatment issues and setting up each and every case for a smooth treatment workflow. This will benefit both the patient and the practice.

Now it’s time to perfect the diagnostic denture to ensure a positive treatment outcome, and use a surgical guide based on the final diagnostic denture to accurately place the implants in the patient’s mouth.

You then take a scan or impression of the healed implants, and your dental lab provides a verification or accuracy jig to verify the accuracy of your scan or impression.Design and construction of the final, permanent prosthesis can now begin.

The last word on multi unit abutments

The take-away message from this guide certainly revolves around the critical importance of accuracy. Whether you’re taking digital scans or analog impressions, working closely with your dental lab on the diagnostic denture, surgical guide and accuracy or verification jig will ensure precise accuracy and help you make large steps towards delivering the best possible treatment outcome.

At Avant, our technicians work directly with dentists at each stage of the workflow to ensure every step is completed to the highest standards. This provides predictability to the dentist throughout the multi unit implant workflow, and supports them to exceed patient expectations with restorations that are as good — or better than — their natural teeth.

Whether you’re talking bar retained dentures, overdenture implants, a direct to fixture implant, or multi unit dental implants there are a range of patient treatment options.

A good dental implant restoration will look, feel and act just like natural teeth. It will last for many years, prevent bone loss, and help to stabilise remaining teeth. A multi unit abutment or an overdenture treatment will also help to prevent premature facial ageing, and improve quality of life for your patients.

However, the reality is a multi unit implant abutment — while an excellent treatment option for some — is not appropriate for all patients.

“Implants are not for everybody,” says Ruben Gurie, an implantology specialist at Dentsply Sirona. “There are certainly indications where you have to tell the patient that you can’t place an implant and an alternative treatment is a preferred option.”

Gurie says proper patient assessment and selection is critical to achieve positive treatment outcomes. “You can’t just say let’s do full-mouth implants without thorough patient assessment,” he explains. “If you do a proper pre-clinical evaluation, you’ll have success.”

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