Laser Doppler flowmetry: reproducibility, reliability, and diurnal blood flow variations

Monte Carlo Simulation of Diffuse Optical Spectroscopy for 3D Modeling of Dental Tissues

Three-dimensional precise models of teeth are critical for a variety of dental procedures, including orthodontics, prosthodontics, and implantology. While X-ray-based imaging devices are commonly used to obtain anatomical information about teeth, optical devices offer a promising alternative for acquiring 3D data of teeth without exposing patients to harmful radiation. Previous research has not examined the optical interactions with all dental tissue compartments nor provided a thorough analysis of detected signals at various boundary conditions for both transmittance and reflectance modes. To address this gap, a GPU-based Monte Carlo (MC) method has been utilized to assess the feasibility of diffuse optical spectroscopy (DOS) systems operating at 633 nm and 1310 nm wavelengths for simulating light-tissue interactions in a 3D tooth model. The results show that the system's sensitivity to detect pulp signals at both 633 nm and 1310 nm wavelengths is higher in the transmittance compared with that in the reflectance mode. Analyzing the recorded absorbance, reflectance, and transmittance data verified that surface reflection at boundaries can improve the detected signal, especially from the pulp region in both reflectance and transmittance DOS systems. These findings could ultimately lead to more accurate and effective dental diagnosis and treatment.

Case-control study analyzing the relationship between oral microcirculation and oral mucositis and pain in patients under antineoplastic therapy

The study aimed to evaluate the relation between microcirculation of the genian region using laser Doppler flowmetry and oral mucositis (OM) and pain in individuals undergoing antineoplastic therapy. A case-control clinical study was conducted with the participants divided into three groups: chemotherapy (CTG), radiation therapy and chemotherapy group (RCTG), and control group (CG). Pain was assessed by visual analog scale; OM was classified by oral mucositis assessment and WHO scales. The blood flow was assessed by laser Doppler flowmetry. Kruskal-Wallis statistical test, Friedman test, and Spearman test were used for statistical analysis of this study. CTG (7 individuals/25.93%) showed the worst manifestations of OM between 2nd and 4th evaluations (OM-WHO: T2, p = 0.006; T3, p = 0.006; T4, p = 0.003; OM-OMAS: T2, p = 0.004; T3, p = 0.000; T4, p = 0.011), and increased blood flow over time, with the exception of the 3rd evaluation (p = 0.138). The RCTG (9 individuals/33.33%) showed the worst manifestations of oral mucositis on the 4th week (OM-WHO and OM-OMAS: p = 0.000) with a decrease in blood flow (p = 0.068). The decreased blood flow is associated with greater severity of oral mucositis and greater pain intensity.

The effects of gingival blood flow on pulpal blood flow detection using ultrasound Doppler flowmetry: animal study

Objectives

This study evaluated the effect of adjacent gingival blood flow on detection of pulpal blood flow (PBF) using ultrasound Doppler flowmetry (UDF) through animal study.

Materials and Methods

The study included 36 right and left maxillary the third incisors and canines in 9 experimental dogs. The study included 2 main steps: In the first step, the pulse sound level (PSL) was recorded on the cervical part of each tooth without flap elevation (Group 1), with flap elevation (Group 2), and after it was repositioned in place (Group 3). In the second step, the PSL was recorded on the cervical part of each tooth (Group 4), after pulpotomy (Group 5), after partial pulp extirpation (Group 6), after complete extirpation (Group 7), and after canal filling (Group 8). In Groups 5-8, the study was performed with and without flap elevation in the left and right teeth, respectively. The PSL was graded as follows: 0, inaudible; 1, heard faintly; and 2, heard well. The difference between each group was analyzed using Friedman's test with Wilcoxon signed-rank tests (α = 0.05).

Results

In step 1, the PSL results were Group 1 > 2 and 3. In step 2, there was no significant difference between the groups when the flap was not elevated, while PSL results were Group 4 > 5 ≥ 6 and 7 ≥ 8 when the flap was elevated.

Conclusions

PBF is affected by gingival blood flow when measured with UDF. UDF measurements require isolation of gingiva from the tooth.

Effects of wearing removable dentures and aging on palatal mucosa blood flow by laser doppler

Aim

The purpose of this work is to analyze the effects of removable dental prostheses and aging on blood microcirculation in the palatal mucosa.

Settings and Design

Blood flow was measured in two groups using the Laser Doppler Flowmeter at three specific anatomical sites: Retro incisive papilla, medial raphe, and Schroeder area.

Materials and Methods

Group 1 included young, healthy dentulous individuals (mean age: 23 ± 3 years), and Group 2 contained elderly edentulous individuals (mean age: 62 ± 11.69 years). For Group 1, measurements were taken in a single session; for Group 2, the measurements were taken in two sessions: The first just before the prosthetic load (E1) and again 1 week after new dentures were provider (E2).

Statistical Analysis Used

Statistical analyses were performed using SAS software, Version 9.4 of the SAS System for Windows, Copyright © 2017 SAS Institute Inc. (Cary, NC, USA). A P < 0.05 was classified as statistically significant.

Results

Measurements of blood flow of the palatal mucosa showed that the healthy young dentulous participants had significantly lower perfusion unit values than the elderly edentulous participants at all three anatomical sites (P < 0.05). For Group 2, the comparisons between the measurements taken before (E1) and after (E2) new dentures were provided showed no significant differences.

Conclusion

Our results indicate that the process of aging significantly modifies the blood flow of the palatal mucosa while wearing removable dental prostheses does not modify the blood flow of the palatal mucosa in a 1week period. These results are not influenced by systemic pathology (e.g., diabetes, cardiovascular diseases) or smoking.

The Decisive Role of Laser Doppler Flowmetry for Pulp Preservation in Discolored Traumatized Teeth

Objective: It has been stated that blood pigments within discolored teeth may interfere with Laser Doppler Flowmetry (LDF) measurements. The aim of this study was to assess pulp vitality with LDF in a cohort of discolored traumatized teeth referred for endodontic treatment or where the referring dentist had doubts regarding maintained tooth vitality. Background: Discoloration of teeth is a common sequel of dental trauma. Still today, it is taken as an indicator for root canal treatment. Transient apical breakdown (TAB) is confused with apical periodontitis, although it is a sequel of dental trauma in young mature teeth and will result in revascularization and dissolution of the apical radiolucency. Methods: A total of 26 patients with 28 discolored teeth, belonging to a cohort of referred patients with traumatized teeth referred for root canal treatment and/or pulp vitality assessment were screened on color with photographs by three investigators, with traditional sensibility tests and with a Moor VMS II LDF meter. Results: The color of the intrinsically discolored teeth was grayish in 58% of teeth, blue 20%, pink/crimson 12%, and yellow 4%. Eighty-five percent were central maxillary incisors, 11% were mandibulary incisors. Thanks to LDF, 43% of the trauma cases in this small cohort with discoloration underwent root canal treatment instead of 70% with traditional sensibility tests as indicator. TAB was found in 11%. Conclusions: LDF was decisive in diagnosing vitality of discolored teeth and there was no negative impact of tooth discoloration on LDF measurements.

How standard deviation contributes to the validity of a LDF signal: a cohort study of 8 years of dental trauma

The aim of this cohort study was to document the potential of laser Doppler flowmetry (LDF) for diagnosing tooth vitality in traumatized teeth in a population of 88 referred patients with dental trauma over a period of 8 years (2011-2018). The main reason to refer was tooth discoloration (26%), and the main trauma cause was a traffic injury (35%). Taking into account that referral for LDF is best given within the week after trauma, 66% of referrals were overdue. In 73% of cases, root canal treatment could be avoided, and in 65%, the presence of a fixed orthodontic retainer showed beneficial for pulp recovery. Data of 394 teeth were collected and submitted to multilevel modelling statistics. As a general conclusion, both LDF perfusion and concentration values proved to be highly reliable in the appreciation of tooth vitality. The difference of variability of standard deviation and range of LDF measurements involving intra-subject control teeth showed statistically significant in discriminating between vital and non-vital pulps. In non-vital teeth, the diagnostic combination of LDF, sensibility tests and peri-apical X-ray is advised.

Diurnal variations and pulpal status: is there a need for FFT besides LDF?

The aim of this article was to investigate the use of laser Doppler flowmetry (LDF) combined with a fast Fourier transformation (FFT). LDF data in relation to three different scenarios were evaluated: (a) LDF records of a right central upper incisor of one patient were used for FFT analysis. These records were obtained by means of 30 pre-manufactured splints, handled by dentists without any experience in LDF recording. (b) Diurnal variations in one patient were analysed with LDF and FFT using 11 splints by one and same experienced investigator at four specific moments of the day. (c) Pulpal status was analysed using 17 splints. Eleven for a patient, standing as case model and six splints for six other patients. In this specific group, each patient had one vital and one non-vital central maxillary incisor and was analysed separately by LDF and FFT. The data of assessment (b) showed diurnal variations on LDF values of almost 80%, indicating that LDF registration is best performed in the same time period of the day. Data verification with FFT confirmed the findings without FFT of assessment (a) and (b). In assessment, (c) FFT demonstrated a clear distinction between a vital and a non-vital pulp for those cases with one vital tooth and one root canal treated tooth. In those cases with one vital incisor and the other traumatised, FFT was undeterminated. Considered that FFT was obtained after LDF recording and remained undeterminated for a decision in cases with decreasing pulpal blood flow in time, the added value of FFT in pulpal traumatology was minimal.

The use of laser Doppler flowmetry to evaluate oral soft tissue blood flow in humans: A review

The objective of this work is to define the conditions for improving the use of laser Doppler flowmetry (LDF) and to determine the limits for the use of this technique. This article systematically reviews the literature on the evaluation of oral soft tissue blood microcirculation by LDF. We analysed the available literature through October 2016 using the database resources Medline/PubMed, the Cochrane Oral Health Group Specialist Trials Register and the ISI Web of Knowledge. Several points emerged from this literature review The use of LDF involves specific constraints; however, the influence of different factors (temperature, tobacco, pressure etc.) must be adequately controlled when using LDF. LDF measurements of soft tissue within the oral cavity vary depending on the anatomical site. In dentistry, LDF can be used to track healing progress in periodontal surgery and to diagnose vascular flow changes in the connective tissue of mucosae covered by a removable prosthesis at an early stage prior to the onset of clinical inflammation signs.