Treatment of patients with combination syndrome can be a challenge for a dental practitioner. A significant resorption of anterior maxillary alveolar ridge is often seen when mandibular molars and premolars are lost and the anterior mandibular teeth with a distal extension RPD oppose the edentulous maxilla. When the lower RPD is constantly adjusted and properly maintained as the bone loss progresses, the deteriorating effects of CS can be postponed and less severe. When patients do not return for follow-up care and/or RPD is not well designed, the continuous resorption of the posterior mandibular bone leads to a loss of posterior occlusion with opposing maxillary denture teeth³. Mastication then shifts to the anterior regions that are bio-dynamically not designed for a heavy occlusal load. An adverse chronic pressure is placed on the anterior portion of a maxillary denture and the resorption of the premaxillary alveolar bone follows resulting in the combination syndrome (anterior hyperfunction). This unfortunate and progressive chain of events that causes an overgrowth and hypertrophy of some parts of maxilla and mandible as well as resorption and atrophy of other areas of the jaws is the result of a pathologic bone remodeling and can be explained by Wolff's law. Wolff's law states that “bone, either normal or abnormal, will develop the structure most suited to resist those forces acting on it.”³³ In other words, bone is deposited and resorbed in accordance with the stresses placed upon it. Recent experimental research has also indicated that bone resorption is a pressure-regulated phenomenon.³⁴ Although theoretically these bone changes could be reversed with return to the original bone condition if the source of pressure is removed (pressure-counter pressure), practically these changes are permanent and do not reverse on their own.

Although a traditional treatment with a complete maxillary denture and distal extension mandibular partial denture is still common, osseointegrated implant-supported or retained treatment has become more prevalent and has physiologic indications in CS cases.

A surgical and prosthetic rehabilitation of these patients in the office setting with dental implants in many cases may appreciably control and correct the deteriorating effects of CS. An establishment of an implant-supported posterior occlusion can help to redistribute the heavy masticatory load posteriorly and allow anterior bone regions of the jaws to “rest.” This can confront anterior hyperfunction and control anterior maxillary resorption.

Prior to or at the implant surgical phase, the hypertrophy of posterior maxilla and overgrowth of maxillary tuberosities can be corrected with an alveoloplasty and maxillary endosseous implants can be placed in a better vertical relationship. If subantral augmentation (sinus lift) is needed, this can also be done with a direct (Tatum) or indirect (Summers) method.

In the case described in this article and many other similar CS cases, 2 splinted implants for each posterior region of maxilla can provide retention for an implant-assisted overdenture. If possible, placement of 3 to 4 implants into the posterior maxilla on each side can provide a good foundation for an implant-supported fixed or removable prosthesis without an additional soft or hard tissue support. This often creates enough rigidity in the system to resist a prolonged posterior occlusal load in the area of poor bone quality.

It seems that using a single implant in the posterior maxilla on one or both sides in these cases will have little retention benefit over a conventional full upper denture. Also, non-splinting of implants placed into poor quality bone of posterior maxilla may compromise the treatment outcome due to a possibility of uneven load distribution and eventually an implant(s) loss.