Pontic Design in Prosthodontics

The pontic, \pŏn΄tĭk\, is an artificial tooth on a fixed partial denture that replaces a missing natural tooth, restores its function, and usually restores the space previously occupied by the clinical crown. An ideal correctly designed posterior pontic should have the following features. 

1. All surfaces should have convexity with proper finish. 
2. The contact with buccal contiguous slop should be minimal (pinpoint)) and with pressure free (modified ridge lap). 
3. Buccal and lingual shunting mechanisms should conform with those of the adjacent teeth. 
4. The occlusal table should be in functional harmony with the occlusion of all of the teeth. 
5. The overall length of the buccal surface should be equal to that of the adjacent abutment teeth or pontic. 

Figure 1. Schematic presentation of various pontic designs; (a) Sanitary pontic; has no contact with the edentulous ridge, (b) ridge lap pontic; forms a large concave contact replacing the contours of a missing tooth, (c) modified ridge lap; shows illusion of a tooth but it has all or nearly all convex surfaces for easy cleaning and minimize plaque accumulation, (d and e) bullet/conical; rounded and cleanable smaller tip in relation to overall size, (f) ovate; round end design currently in use where aesthetics is a primary concern[1].

The Pontic design can be classified into two types:

A. Pontic having mucosal contact 

1. Sanitary/Hygienic/Fish-belly
2. Modified sanitary type 

B. Pontic with no mucosal contact      

1. Saddle/Ridge lap 
2. Modified Ridge Lap 
3. Conical
4. Ovate 

Sanitary or Hygienic Pontic or Fish-Belly  

Sanitary pontic makes no contact with the edentulous ridge. It is made in an all-convex configuration, facio-lingually and mesio-distally. The space between the pontic and the mucosa should be 2 or 3 mm [2]. It is the most commonly used mandibular molar replacement pontic design. It has the advantage of providing good access for maintaining hygiene with the disadvantage of poor esthetic. 

Sanitary pontic design

Modified Sanitary 

The tissue facing surface of the modified sanitary design pontic has a hyperbolic parabola. The pontic is designed as a concave archway mesio-distally while the under surface is convex facio-lingually. It is indicated in molar replacement, provides access to the under-surface for good hygiene, along with poor esthetic.  

Modified sanitary pontic design-note the concavity at the cervical region.

Saddle/Ridge Lap 

It looks like crown of the tooth because it replaces all the contour of the missing tooth. It maintains a large concave contact with the underlying ridge and obliterates facial, lingual and proximal embrasures. Esthetic wise it provides the best result but due to impossible access to under-surface for cleaning, its use is limited for the replacement of maxillary incisors. 

Saddle/ridge lap pontic design

Modified Ridge Lap 

The modified ridge lap combines esthetic with easy cleaning and makes contact with ridge tissues in the shape of ‘T ‘ whose vertical arm ends at the crest of the ridge. This design is most commonly used in the area of the mouth that is visible during function, e. g. anterior teeth, premolars and sometimes maxillary molars.  

Modified ridge lap pontic design: note the half concave underneath surface in contact with mucosa.

Conical 

Conical pontic design is mostly limited to the replacement of thin knife edged ridges in the non-display zone of the mouth. It has a convex surface with only touching the center of the residual alveolar ridge. It helps maintain good hygiene with poor esthetic. Conical design is indicated for the replacement of molars. 

Image of conical pontic design- note the egg shaped design in green circle.

Ovate 

Ovate pontic design is the most aesthetically suitable appealing design that looks like emerging from the gingiva. When ridge resorption is corrected by ridge augmentation, ovate design appears to be emerging through gingiva just like natural tooth. it is indicated for the replacement of maxillary incisors, canines, and premolars. It has the advantage of best esthetic, negligible amount of food entrapment and easy cleaning. The disadvantage is the requirement of surgical preparation of the receiving site before prosthesis fabrication. 

Ovate pontic design-note the convex under-surface of pontic embedded in mucosa (green circle).

 

References:

1. Eur J Dent. 2018 Jul-Sep; 12(3): 375–379. doi: 10.4103/ejd.ejd_232_18
2. Rosenstiel & Tyllman respectively
3. Pontics

 

What should you look for before starting a crown preparation?

So, you are ready to start your crown work for the patient who is eagerly waiting to regain the lost functional ability, phonation and aesthetics. The functional ability, aesthetic value, speech enhancement and self-confidence of the patient will enhance when you look for the following anomalies in the oral cavity and rectify them, before the commencement of the crown preparation. You can make your crown & bridge without giving a dam for these factors, and get the quick bucks. But, it would be a good idea to consider them before you jump on for crown preparation part. And believe me, in long run, you will gain the faith of your patient, converting into your most reliable source of referral and image builder. These factors are given below:

• General overall health of the oral cavity
• Expectations of the patient
• Extremely tilted teeth
• Mobile teeth
• Type of occlusion
• The type of crown you want to fabricate for your patient

When we start examination, we look for the general health of the oral cavity. Is it healthy? Does the oral hygiene acceptable? Does the periodontal status of the tooth concerned adequate? Is the tooth tilted, rotated, supra or infra erupted? Does the patient need oral prophylaxis? What are the other systemic diseases the patient is suffering with; for example, cardiac, endocrine, orthopaedic, and physiological?  If any of the answer is yes, then the dentist needs to take care of them first, before the commencement of the crown preparation. Of course, few chronic diseases cannot be cured but they should be kept under control by the patient’s’ physician.

That preparatory phase, the phase that involve the work done inside the mouth so that the longevity of the prosthesis remains satisfactory, includes the scaling and root planing, the removal of hopeless mobile teeth, orthodontic correction of tilted tooth, and occlusal surface adjustment of the supra erupted tooth. The other decayed teeth should be appropriately restored.

You should also know that what type of crown you plan to provide or what type of crown the patient is wishing for? What are the expectations of the patients from a particular type of crown? Will the patient understand the significance of the particular type of crown? Does patient understand the inherent drawbacks of that particular crown? Does patient know and ready to accept the post insertion maintenance care?

The other consideration is the type of occlusion in a patient. Is it canine protected or group function? Will you be needing to alter it for the betterment of the function and longevity? Does patient has any TMJ issue?