The integrity of dental arches is maintained through proximal contact areas. The anterior force of occlusion has been shown to stabilize the dental arches and to help maintain proximal integrity. Teeth are stabilized by contact with adjacent teeth and by occlusal contacts with the opposing tooth. Weak or slightly open contacts can create issues for patients relative to chewing comfort and maintenance. Open contacts may allow for food impaction that can be very discomforting to patients.
Long-standing open contacts could create periodontal inflammation and subsequent bone loss. This bone loss can contribute to more extensive tooth migration and occlusal disharmony. Additionally, dental caries is another concern related to food impaction. Therefore, maintaining proper proximal contact in natural dentitions is important.
Proximal contact strength
Proximal contact strength (PCS) is generally measured by passing floss through the interproximal surfaces of the teeth. The presence of a “snap” signifies that adequate tooth contact exists. This determination is unscientific.
Proximal contact strength has been measured in numerous articles in the literature. PCS is not a constant value. There are differing measurements between various teeth and dental arches. The magnitude is the critical aspect that affects clinical situations.
C.E. Dörfer and a team studied PCS and concluded in the European Journal of Oral Sciences that proximal contact force is a physiological entity of multifactorial origin. They determined that PCS is lower in the maxilla than in the mandible.
In the study, the lowest contact strength existed between the upper canine and the first premolar. The highest contact strength existed between the lower premolar and the first molar. Not only was it determined that contact tightness varied between tooth location and the time of day (morning vs. afternoon), chewing and mastication also contributed. Body posture and positioning have also been shown to be contributing factors to contact tightness and change.
Clenching forces have shown to contribute to opening of contacts as teeth can be displaced. Open tooth contacts can be frustrating for both patients and dentists, as food impaction can cause gingival inflammation and bleeding. Managing these open contact situations is important to maintain periodontal health and restore stability of occlusion.
Restoring open proximal contact is a viable option for managing these situations; however, in cases where virgin teeth exhibit open contacts, alternatives to restoration are very important. Here is a simple technique that can easily and effectively manage open contacts in the molar region.
Fabricate in the dental office
I will use a clinical example to describe and outline the technique for closing interproximal spaces. My patient, Matt, scheduled an appointment for evaluation of an open proximal contact of his second maxillary molar.
He complained of food trapping, gingival irritation, and bleeding. Matt does have a history of clenching but does not wear a protective occlusal splint. At age 40, he has had no dental restorations and is caries-free. As a regular flosser and a consistent dental re-care patient, this situation was frustrating and irritating to him. He asked for a solution to this concerning problem.
The technique applied to these situations is very simple and easily managed in the dental office (versus dental laboratory collaboration). Once the open contact has been verified, an evaluation and correction of occlusal contact is performed. Opposing “distal wedging” forces are adjusted and corrected. Elimination of these occlusal contacts is paramount for successful proximal contact management and closure. An alginate impression is obtained and poured in hard stone (die stone).
Once the poured model is hardened and trimmed, the contact closure technique can be applied. Horizontal parallel lines are scribed on the buccal (and lingual, if desired) aspect of the stone teeth involved in the open contact. Extend the lines at least one tooth forward of the open contact. These lines are used as re-positioning reference points once the die cuts are completed.
Using a plaster saw or a rotary disc, separate the distal tooth from the stone model. Separate the tooth directly at the mesial and distal contact points of the stone model. Once the vertical cuts are complete, detach the tooth by making a horizontal cut approximately 2-3 mm gingival to the facial/buccal gingival margin. I utilize a plaster saw for the vertical cuts followed by a lab engine and a #557 straight shank cutting tool for the horizontal sectioning.
The separated tooth is then reset in the stone cast with wax. If needed, the proximal contact of the freed tooth is contoured to allow for increased tightness and sufficient contact closure. This tooth is secured in place with pink baseplate wax. The scribed lines allow for proper positioning in a vertical dimension.
With the contact closed and the stone tooth secured to place, an aligner tray is fabricated on the corrected cast. The Great Lakes MiniSTAR vacuum system is efficient in fabricating well-fitting aligner trays. Clear Splint Biocryl 1 mm tray material is the recommended thickness for efficiently moving the tooth and closing the contact. The aligner tray is trimmed to the gingival margins' both buccal and lingual.
The patient is instructed to wear the aligner for approximately 20 hours per day. The tray should only be removed for eating and home care maintenance. In my experience, most contacts are fully closed within 2-3 weeks. At that point, the patient is “weaned” from all-day aligner wear to nighttime only. If appropriate, a bruxism/occlusal splint may be fabricated to replace the aligner tray as a long-term occlusal management solution.
This simple tray closure technique has been a game-changer for circumstances in which open posterior contacts have occurred. These aligners are not only well accepted by patients, but they create an opportunity to manage frustrating circumstances in a practical and noninvasive manner. I hope you will find this simple technique as effective and efficient as I have.
Jeffrey Bonk, D.D.S., is a member of Spear Resident Faculty.
Kasahara K, Miura H, Kuriyama M, Kato H, Hasegawa S. Observations of interproximal contact relations during clenching. International Journal of Prosthodontics. 2000;13(4).
Oh SH, Nakano M, Bando E, Shigemoto S, Kori M. Evaluation of proximal tooth contact tightness at rest and during clenching. Journal of Oral Rehabilitation. 2004;31(6):538–545.
Conroy, John J. (1994).An investigation of the posterior component of occlusal force. AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING.
Kadam KS, Swapnil SK. Proximal Contact Areas: A Forsaken Facet of Restorative Dentistry. Acta Scientific Dental Sciences. 2019;3:33-34.
Dörfer CE, Von Bethlenfalvy ER, Staehle HJ, Pioch T. Factors influencing proximal dental contact strengths. European Journal of Oral Sciences. 2000;08(5):368-377.
Kim H-S, Na H-J, Kim H-J, Kang D-W, Oh S-H. Evaluation of proximal contact strength by postural changes. The Journal of Advanced Prosthodontics. 2009;1(3):118.