Spectrophotometry is Superior to Photo Analysis in Peri-implantitis Ink Model

Objectives: Debridement has been demonstrated as an effective method for biofilm removal during peri-implantitis. Currently, software-aid photo analysis is extensively used for assessing efficiency of different types of debridement methods on in-vitro, ink-based models of plaque accumulation; however, it has several limitations: bidimensional rendering, technical biases (shadows, parallax error, software setup, equipment quality), and inter-operator variability. Herein, we propose a reliable alternative for evaluation of debridement efficiency on implants, based on spectrophotometry.
Methods: Twenty dental implants were randomly assigned to 4 different groups (n=5/group) according to staining. Red ink was used for staining implants to different levels from the apical surface: 0 mm (no ink), 4mm, 8mm and 12mm. Implants were stained simultaneously with a custom-made jig to the described levels. In order to define the ink absorption (ABS) wavelength peak, different dilutions of the ink were tested spectrophotometrically. Photos of implants were subjected to stereomicroscopy, and analyzed planimetrically by dedicated software (ImageJ v1.46, NIH, Bethesda). Vibrating the implants that were placed in 5mL leak-proof tubes with 5mL ethanol (95%) dissolved the staining. ABS of the obtained solutions was assessed in blinded fashion (3x).
Results: Ink ABS wavelength was assessed at 534nm. No difference between software-aid photography and spectrophotometric analysis was found (p>0.05). A positive strong correlation was found between methods (R²=0.923, p<0.001). Receiver Operating Characteristic (ROC) analysis revealed high specificity/sensibility (AUC=97%) for the spectrophotometric method.
Conclusions: Spectrophotometry is comparable to photo analysis in the assessment of debridement efficiency, and overcomes its many intrinsic and extrinsic limitations. This method is not affected by typical photo biases, like parallax error, shadows and software capability to discriminate ink-colored surfaces. In addition, it allows the evaluation of debridement efficiency in the entire implant surface, not limited to the bidimensional photo rendering. Potential applications may also extend to restorative dentistry (e.g. cavity cleaning) and endodontics (e.g. canal shaping). ROC analysis deserves further validation with larger numbers.