Bone-crest height after maxillary implants in individuals with different deoxypyridinolinuria/creatinuria

Background: Accurately predicting bone re-absorption before dental-implant procedures could potentially reduce the frequency of therapeutic failures. Deoxypyridinoline (Dpd) is a type I collagen present in bone and excreted in urine without metabolic stages. Due to circadian variations, Dpd urine levels are normalized by comparing them to creatinuria, using the deoxypyridinolinuria/creatinuria ratio (Dpd_U/Cr_U). Since changes in Dpd_U/Cr_U manifest earlier than findings in bone densitometry measurements, this could be a potential predictive biomarker of excessive bone re-absorption in the context of dental implants.

Objective: To compare the bone-crest change in a group of patients with elevated Dpd/Cr_U, versus a control group with normal Dpd_U/Cr_U, after the placement of upper maxillary dental implants.

Method: After being granted IRB approval, 20 controls with normal Dpd_U/Cr_U (2.3-5.4 females; 3.0-7.4 males) and 20 patients with high Dpd_U/Cr_U were enrolled from all individuals undergoing placement of upper maxillary dental implants, at the Center for Dental Studies and Research in Bogotá, Colombia. The Dpd_U/Cr_U ratio was measured, using a solid-phase chemo-luminescent immunoassay technique. The height of the bone crest was radiographically measured at baseline and two months after the implant procedure.

Distributional and homocedastic assumptions were tested with Shapiro-Wilk’s and Fisher’s test, respectively. Mean differences for continuous variables were tested with Student’s T test. In all cases α=0.05.

Results: The mean loss of bone-crest height was statistically larger (p=6.0x10^-4) in patients with high Dpd_U/Cr_U (0.402mm), versus controls with normal Dpd_U/Cr_U (0.013mm).

Conclusions: Due to the statistically significant difference in bone-crest change between patients with a high Dpd_U/Cr_U ratio versus controls with a normal Dpd_U/Cr_U ratio, this study adds evidence to support the potential usefulness of this measurement to predict the degree of bone-reabsoprtion after the placement of dental implants. Further confirmatory studies are needed to confirm and expand these findings, including more stringent clinical endpoints.