prostho sheet # 1-Mohammad abukar

Terminology
Prosthesis: replacement of any absent part of human body by an artificial part (ex. Prosthetic leg, arm, etc.)
Prosthodontics = Prosthesis + Dentistry
Prosthodontics: Branch of dental art and science pertaining for the restoration and maintenance of all the functions by replacement of missing teeth and structures by artificial devices. (The underlined words are common in the definition of all dental branches).
Denture (طقم): Artificial substitute of the missing teeth and adjacent structures.
 It’s important to understand that a dentist don’t only replace missing teeth because when a patient loses teeth he also loses other structures (especially related to the function of the teeth). Just like muscle atrophy resulting from immobilization of bone of the leg for example.
Complete denture: Dental prosthesis that replaces all of natural dentition and associated structures in maxilla or mandible.
 A denture can be either fixed or removable (conventional complete denture).
 Fixed denture can be done for edentulous patients by using implants instead of teeth to fix the denture in top of.
Partial denture: Dental prosthesis that replaces one or more but less than all of natural dentition and associated structures in maxilla or mandible.
 Partial denture can as well be fixed or removable.
Removable partial denture: A partial denture that can be removed and cleaned by the patient.
Etiology of teeth loss: Etiology = the study of causes
1- Caries.
2- Periodontal disease (affecting periodontium).
3- Trauma.
4- Iatrogenic dentistry (malpractice for example extracting a healthy tooth instead of the diseased one).
5- Congenital missing (A common in which the patient is born with no teeth or less than normal teeth.)

 Tooth loss pattern range from a single tooth to all teeth.
 Partial teeth loss can be restored by many treatment modalities
 Patients having some teeth enable the dentist to make a fixed partial denture (جسر) that is fixed on top of two of the remaining teeth that were prepared for the treatment by reduction of size.
 In removable partial denture the dentist doesn’t prepare the teeth. Instead, he makes a denture that “clips” onto the remaining teeth by clasps.
 Implant-retained prosthesis can be used for a single missing tooth, many missing teeth, all missing teeth.. all cases are treated by implants.
 Implants can be used for both removable and fixed dentures.
 Metal pieces used in implants are made mainly from titanium.
 Partial denture can move a little bit correlating with the movement of the teeth in their sockets and it will move during function.
 Most of cases in which dentists apply partial denture can be treated by implantations, the limitation of use is due to the high cost of the implants mainly and sometimes due to biological issues (i.e. the patient doesn’t have sufficient bone for the implantation and so the nerve may get injured if implantation is used.
Revising oral anatomy, we have facial muscles and certain oral muscles just like orbicularis oris (doctor called it once circumoral muscle) originated from bone and not inserted on teeth but supported by teeth and bone. So, in case of loss of teeth the muscle will retract. Behind orbicularis oris is the buccinator muscle (of the cheek) attached to the superior constrictor of the pharynx muscle through pterygomandibular rahphe which is the superior constrictor muscle of the pharynx. And they all form a ring around the oral cavity. This ring will collapse if it lost its anterior support and that is why you may predict that a patient is edentulous without him to open his mouth (collapsed lower face).

As dentists, we have to restore all missing “things” not only the teeth and therefore we have to place the denture in the correct position to regain the normal shape of the lower face as much as possible.
Anatomical changes associated with loss of teeth:
Edentulous people have much less pressure exerted on their mandibles causing more bone resorption than bone formation and that is why by comparing between dentate and edentulous mandibles we’ll notice that the distance between mental foramen and the top of the bone is reduced and the same applies on genial tubercle posteriorly.
 Bone loss depends on time (i.e. the longer the time since the loss of teeth the more the resorption is) and also depends on the cause of teeth loss (e.g. If the patient is suffering a periodontal disease the bone will be somewhat damaged before the loss of teeth and the situation will worsen after it and we have to deal with bone loss in complete denture treatment.
 Changes of facial appearance of edentulous patients are caused by the loss of teeth, resorption of alveolar bone that supports oral tissues and resorption of bones that support the facial muscles.
 Edentulous can move the mandible closer to the maxilla than normal person. A patient can’t make a contact between the upper and lower ridges just after losing his teeth if this situation lasted for several months the ridges may come in contact and the patient can use them for eating because of elongation of ligaments that restricts this movement but even without elongation, loss of teeth will allow mandible to go closer to the maxilla and that is why the lips and cheeks of the patient may seem collapsed and the wrinkles become more because of loss of muscular support that occurred due to bone resorption that in turn supports the muscles.
Objectives of prosthetic treatment
1- Restore masticatory function.
Edentulous patient don’t die from hunger but it is enjoyment of life.
2- Social demand and personal demand (improve appearance)
3- Improve speech
Even if the patient tried to speak without teeth some derangement will still.
Denture:
 A denture is formed of teeth and denture base (pink)
 Denture base is like a saddle that transmits rider’s weight to the horse by its lower surface but its upper surface should be comfortable for the rider.
 Only the occlusal surface is needed in artificial teeth, root is not needed.
 The most common material of denture base is the acrylic material. The acrylic material we’ll use for denture bases will be heat cure acrylic material (Powder and liquid mixed and heated to become solid)
 Chemical cure acrylic material that doesn’t need to be heated and light cure acrylic material that dries (hardens) when light applied are also available
 Heat cure acrylic material is peculiar for complete dentures or dental partial dentures for denture bases.
Putting the maxillary denture over the mandibular one and having a vertical section we’ll notice:
The upper arch should be continuous while the lower is not as we have to keep a place for the tongue.
Denture can be divided into three surfaces:
1- Fitting surface: reflection of denture base done to make contact with the oral tissues that support the denture (masticatory mucosa attached to the bone). It is a negative replica of the oral tissues.
2- Occlusal surface contact with the opposing dentition (arch)
3- Polished surface (named because we polish it) these surfaces contact with the tongue and cheek. Polished surfaces are important because they will support the muscles of the cheek. We have to put the denture in the exact place so it will irritate neither the tongue nor the cheek. Therefore, the place of the denture is not arbitrary but determined by intraoral factors.

 Polished surface is polished to make it hard to get dirty but in other surfaces our priority is to the accuracy.
Complete denture treatment procedure has two phases: preparatory and construction
Preparatory Phase:
The patient visiting the prosthodontist may not be ready for treatment and he may first undergo some examinations, treatments and even surgical operations if he has tumor. Oral health should be optimum and before applying the denture and the structure that will be underlying it should be healthy.
Construction phase:
Five main clinical appointments between every two of them there is a laboratory step:
1- Primary impression: lab work is to get the model.
2- Secondary Impression: A dentist make a special tray specific for the patient over the primary model and take another impression that will be more accurate. Lab work will be by making the (master model/secondary model/ secondary cast/ working cast)  all are names for what a dentist gets from the secondary impression.
3- Taking the relations between maxilla and mandible and the patient’s bite Lab work is to use articulator (representative to the maxilla, mandible and TMJ) and make fixation of the arches according to the relations we got from the patient’s mouth.
4- We remove some of the wax (bite blocks) and we fix the artificial teeth on the denture and then we apply it to the patient’s mouth to check whether it is suitable or not and to notice what needs improvement. Everything (wax) but the teeth is disposable
5- The Model is done.
the lecture is an introduction and therefore WILL HAVE NO QUESTIONS IN THE FINAL

This sheet is dedicated to:
Yousef Khoury

Done by: Mohammad M. Abukar

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