Problems with ALL ON 4

For millions of Americans who are edentulous or have broken down teeth, one of the implant based treatment known as “ALL ON 4” can be a viable treatment option. Four to six implants are placed in the jaw bone which will support the zirconia or acrylic teeth  that can easily restore patient’s chewing ability and smile. The implants can be tilted to avoid anatomical features and thus may not need bone grafting or sinus lift procedures.  

“ALL ON 4” or “ALL ON 6” is nothing but implant based full mouth reconstruction that requires teamwork and coordination with a high quality dental lab that physically produce the final teeth for the patent. This treatment is very technique sensitive and the success of the treatment depends on proper initial treatment planning, expertise of the treating dentists and excellent team work among the surgeon, restoring dentist and the dental lab.

Along with the popularity of the ALL ON 4, patient’s complaints about ALL ON 4 also have soared.

A patient recently came to me with an ALL ON 4 that completely broke loose inside her mouth. Examination revealed that all screws connecting the prosthesis to the implant broke and one implant was compromised with poor prognosis. The ALL ON 4 prosthesis was of poor quality and it lacked key design features.

As a Prosthodontist, I have come across many patient complaints like lack of aesthetics, unpleasant smile, problems with chewing, prosthesis fracture and poor hygienic designs for  ALL ON 4 teeth, all of them leading to failures and patient dissatisfaction.

Problems with Inadequate Treatment Planning
Many problems with ALL ON 4 originate from poor treatment planning prior to the surgery. If the restorative dentist is not involved in the treatment planning or restorative dentist fails to spend time needed for proper treatment planning or fail to communicate with the surgeon, implants placement may be compromised. These problems will have negative impact on the restorative phase of the treatment and they are not easy to correct later in the treatment phase.

Implant placements play an important role on the ALL ON 4 restoration and final prosthesis durability. Unsupported teeth beyond the implants can break off due to excessive stress. Too much stress on the implants due to poor treatment planning can lead to bone loss and implant failures. These problems are amplified for patients with a history of bruxism and proper treatment planning must be done to overcome the grinding forces of bruxism.  

Problems with ALL ON 4 restoration process
ALL ON 4 restoration leading to final prosthesis is a highly technique demanding process with numerous stages and patient try-ins. The restorative dentist must pay close attention to all the steps involved in this process and direct the dental lab with every step. If these steps are not followed or proper patient trials are not completed, the final prosthesis may not live up to the expectation of the patient and patient can experience difficulty with chewing, may affect esthetics and durability of final prosthesis.

Poor Construction of ALL ON 4 Prosthesis (Teeth)
Not all dental labs are same and that will be reflected in the quality of the final ALL ON 4 prosthesis. The restorative dentist must ensure that the prosthesis is constructed correctly with high quality materials selected for the prosthesis. The design of the ALL ON 4 must avoid collecting of food inside and sharp edges and ledges must be avoided. Original implant parts and screws must be used to avoid mechanical failures of the prosthesis. Ability to clean is a big issue for the patient and the design of ALL ON 4 must allow easy everyday cleaning.

ALL ON 4 materials of construction
Patient must be aware of the limitations of ALL ON 4 materials of construction. The final ALL ON 4 prosthesis may be made from plastic (PMMA) or Zirconia, the choice may be made based on cost or clinical limitations. The PMMA prosthesis tends to wear faster. The PMMA is a porous material that is prone to stain. The Zirconia is harder and aesthetically superior however, the ceramic layer may chip or fracture, especially if the occlusion is not perfected.

Patient Expectations
Patient expectations play an important role in ALL ON 4 patient satisfaction. Most of the ALL ON 4 patients didn’t have natural full dentition for a long time and ALL ON 4 suddenly introduce a foreign object into the mouth that patient must get adjusted to. There are some inherent problems with the implant supported full arch denture that patient must be aware of. The natural tooth has nerve and it has proprioception which protects the teeth from pressure and excessive forces. The dental implants do not have proprioception and  thus it lack this protective mechanism. Hence any bite problems may be exacerbated leading to prosthesis chip or failure. Patients are advised to eat slowly and carefully and thus develop a safe chewing pattern and chewing muscle memory with their new ALL ON 4 teeth.

ALL ON 4 prosthesis teeth do not come out of the gum like natural teeth. Patient may feel that the new ALL ON 4 teeth is bulky and it always touching the cheek and tongue. There is an adjustment period and patient must slowly get used to the prosthesis in the mouth.

Caring for your ALL ON 4 teeth
Routine care includes water floss and super floss to avoid food accumulation under the prosthesis. 4-6 month hygiene appointments to clean the gum around the implant area is a must. Patient must wear a soft night guard to protect the prosthesis at night.
The screws supporting the prosthesis on implant will fatigue and fail over time. Patients are advised to go to the restorative dentist and remove the small screws and replace them with original new screws every few years.