The Implant Bar Challenge
In this article, we will discover the step by step documentation of Christian von Bukowski, DT on his implant bar case involving a Double Structure and a Wrap-Around for a 63-year old female patient.
The patient
The patient is a 63-year-old female who has been wearing dentures for many years. She was tired of having constant problems with ill-fitting dentures. She had 5 implants placed in the upper arch and 4 implants in the lower arch. She has good oral hygiene so a compromise between fixed and removable was decided for this patient. Patient has requested a natural looking appearance.
Implant bars
The upper dental implant bar is a Double Structure milled implant bar. Incorporating MK1 and CM Loc attachments offering the patient a combination of fixed and removable prosthesis. The case will be done on 5 Zimmer ACTR implants. The lower is a fixed Wrap-Around milled implant bar. The case will be done on 4 NobelBiocare Multi-Unit RP implants.
Doubling
After preparing the models, a doubling mold is created. When it this hardens, impression screws must be loosen (this is very important). Afterwards the original models are removed, the doubling mold is cleaned and new lab analogs are screwed into the impression posts. Then plaster can be mixed and poured into the mold.
Bite registration
A bite registration is received from the dentist, allowing us to assign the upper jaw and lower jaw in their relation. In addition, it also provides us with the following base measurement data: The canine line, smile line, midline and the occlusal plane.
Working models
A split-cast base with magnets is made on both working models. That way, they can be separated from the articulation base and reduced at any time during case processing. This is made, in order to avoid height problems at the moment of model placing when in the light-curing unit and makes it easer to handle. Now we have the working models ready to be placed in the articulator.
Setting in the articulator
The mandible is aligned in the articulator using the bite registration. Then the mandible is fixed with the kneading silicone. The incisal pin and a thin rubber band are very useful here. After that, is time to mount the upper jaw. When the plaster has hardened, the silicone positioning aid is removed and the lower jaw is loaded in.
Setting working models
Silicone key is made over the bars on the original models. Then upper jaw is adjusted with it. Afterwards, the lower jaw is aligned accordingly to the model. With all preparatory actions made. The model analysis can be taken.
Model analysis
Objectives: Assesses the anatomical shape of the upper and lower jaws, recognize the intermaxillary relationship between jaws in transversal and sagittal direction and determine of the occlusal concept, according to selected tooth.
Teeth set-up is done based on the following criteria
Normal bite, unilateral crossbite, bilateral crossbite and lingualized occlusion according to Dr. A. Gerber. Important information according to static, prosthetic, esthetic and phonetic is gathered. The objective is to correctly set up the replacement teeth. Always focused on where teeth used to be. Note: It is important that the muscular balance is not disturbed.
Evaluation of model situation by static lines markings
We determine here important information that we need to be able to set up the replacement teeth according to static, prosthetic, esthetic and phonetic aspects. The focus here is on where the teeth used to be. It is important that the muscular balance is not disturbed. We need the following markings to evaluate the model situation: Determining the center of the alveolar ridge, the course of the sagittal ridge in relation to the masticatory function and the center stop line in the mandible. Drawing static lines: position of the center chewing and the stop line. Determined points and lines are transferred to the outer sides of the models. Markings of the bite registration are also transferred to the models.
Evaluation in the articulator
Based on the model analysis and intermaxillary relationship between the maxilla and mandible. It’s applied the lingualized occlusion concept developed by Dr. A. Gerber. The Tooth-to-tooth occlusion (mortar/pestle) has proven to be very advantageous for implant supported hybrid prostheses. The masticatory force transmission acts in the direction of the alveolar process and horizontal shear forces are minimized. Now we can make the teeth selection.
Anterior teeth selection
There are some criteria that can build up teeth selection. First, the markings on the bite registration are determining the required width and length of the anterior teeth. In addition, I prefer using a live mold chart. With it, I can get an impression of the actual situation and if possible, have some photos of the natural teeth before tooth loss. Also, teeth shapes, positions and color tastes can be discussed in that appointment. In some cases, a natural look is desired but most patients prefer a slightly lighter color than they had before. Since it doesn’t present any functional disadvantage, that will be a patient decision.
Posterior teeth selection
When selecting posterior teeth, I’m guided by the vertical height relationships and the statically best dorsal extension of the denture. A creation of a lingualized tooth-to-tooth set-up is intended. To achieve this, the appropriate width and occlusal surface shape is needed. Patient and I have decided on the A2 shade, the Vita Excell confection teeth for the front and the Vita Lingoform for the posterior.
In addition, I discussed some modifications with the patient: First, she wanted to change the shape of the ready-to-go teeth a little bit so we can get closer to the original shape of her natural teeth. Also it was decided for canines to be one shade darker (A3), and the position of the anterior teeth will be minimally customized (Slightly turned out 12 and 22). On the gums a natural color effect was decided.
Teeth line-up
Try-in
The try-in appoinment is a very important moment on making dentures. For patients, aesthetics and speech are the most important aspects. Giving them the opportunity to see themselves and try out their speech before the prosthesis is finished gives us the opportunity to make minor or sometimes major changes. The practitioner is interested in the general fit and position of the individual elements such as: occlusion, vertical height, resting position, speaking distance, functional movements, lips and muscle support. So, at the try-in appointment, all important details are discussed. Then the final approval is given for completion.
Completion
For this case, all functional criteria was Ok, even fitting was right. Only few things in the anterior set-up were changed according to patient’s wishes. Next, teeth will be attached to the metal framework with tooth-colored PMMA resin. But before that the silicone vestibules needs to be created. Then the teeth shape is added to framework. Silicone keys are prepared to attach the teeth to the framework with tooth-colored PMMA (New Outline).
Individualize – Upper
A minimal cut-back was made on the maxillary anterior teeth. Internal layering with GC Gradia plus and completed again with incisal material.
Individualize – Lower
The same cut-back procedure as in the maxilla. Internal layering with GC Gradia plus and completed again with incisal material.
Pink PMMA
In the maxilla, as in the mandible, the basic fits are achieved with pink PMMA (Xthetic prime). This can be used to cover the entire framework very well.
Pink composite
Individual layering of the gingiva with GC Gradia plus Gum has now been carried out. The surface was pre-polished with pumice stone. It is always better to obtain a color impression in advance from old patients photos, or a selection based on samples.
Selective grinding of the centric occlusion
The aim is to achieve uniform contact with 12mm foil. Then the dynamics are finely ground in order to achieve a balanced movement pattern in right and left lateral movement and protrusion movement. In this case and due to the previous chewing pattern, the dynamic occlusion was created rather flat.
Final result
Transform your learning experience with these videos
Learn from recognized industry experts how they worked with Panthera Prosthetic products
