Laser Doppler flow measurements of pulpal blood flow and severity of dental injury

Dental Pulp Vascular Response to Early Stages of Caries

OBJECTIVES

During caries progression, dental pulp is increasingly pathologically affected. Since the accurate assessment of pulp is of vital importance in clinical decision-making, this study aimed to evaluate pulpal condition in the early stages of caries via laser Doppler (LD) flowmetry and histologic analysis and determine their agreement.

METHODS

Fourteen patients with severe dental crowding were included. Prior to extractions and orthodontic treatment, dental pulp condition of 52 premolars was evaluated via LD flowmetry. Teeth were assessed for the presence of caries and lesions were graded according to the International Caries Detection and Assessment System (ICDAS). After extractions, teeth were split and histologically stained for endothelial cells with anti-von Willebrand factor and Movat pentachrome for collagen. Volume densities of vessels (Vvasc) and collagen were calculated.

RESULTS

There was a significant negative correlation between LD flow and Vvasc of the dental pulp with ICDAS grade. Pulpal LD flow and Vvasc in teeth with the initial lesion were increased, decreasing with progressing stages of caries. A significant positive correlation between the the pulpal LD flow and Vvasc, and a negative correlation of LD flow with collagen fibre density were noted.

CONCLUSIONS

Caries affects the physiology of the dental pulp, initially with increasing vascularity, and decreasing vascularity at later stges of caries progression. Collagen contents increase with grades of ICDAS. LD flow shows good agreement with the histologic constitution of the dental pulp. Use of clinical measurements of pulpal LD flow could provide a good noninvasive indication of pulpal vascular state and its health.

Evaluation of pulpal blood flow during orthodontic space closure: Prospective clinical trial

INTRODUCTION

Orthodontic tooth movement (OTM) is a biological process that can affect the vascularization of the dental pulp. The forces exerted on the teeth may increase periapical pressure that could compress the arterioles, which in turn affects pulpal blood flow (PBF). The study aimed to investigate how OTM affects PBF during orthodontic space closure.

METHODS

A total of 22 adolescent participants who required orthodontic space closure in mandibular posterior sectors were enrolled in a prospective clinical study. The same sliding mechanics, wires, and active elements were used. Patients were observed before OTM, after leveling before space closure, and at the 4th, 7th, 21st, and 28th during active space closure. PBF was measured with laser Doppler (LD) flowmetry. Dental models were obtained with an intraoral scanner.

RESULTS

The LD flow values decreased significantly during the observation period (2-way repeated measures analysis of variance, P <0.001). There was a significant difference in LD flow between tooth categories (2-way repeated measures analysis of variance, P <0.001). During space closure, the most pronounced LD flow reduction was observed in single-rooted teeth closest to the residual space. A higher speed of OTM was associated with a greater decrease in LD flow on day 4 of OTM (Pearson correlation, P = 0.0299).

CONCLUSIONS

Orthodontic space closure reduced PBF; it was lowest in the early stages of space closure and showed a tendency to increase during the first month. Anterior teeth closer to the interdental space that experiences more OTM and teeth that move faster during initial OTM had a higher risk of reduced blood flow.

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.

Efficacy assessment of laser Doppler imager in diagnosing the pulp vitality after dental trauma

Background/purpose

This is the first paper evaluating the efficacy of laser Doppler imager in diagnosis of pulpal vitality. The purpose of this study was to evaluate and compare the diagnostic benefits of laser Doppler imaging and electric pulp test (EPT) in dental trauma.

Materials and methods

Seven patients were selected for pulp vitality evaluation in Kaohsiung Medical University Hospital between 2018 and 2019. EPT and laser Doppler imager evaluation were performed for patients with traumatic injury to teeth. Statistical methods included the Kappa consistency test and the chi-square test. In addition, the receiver operating characteristic (ROC) curve, and the area under the curve (AUC) were used.

Results

There was a significant difference in Doppler flow values between the severe trauma group and the mild trauma group, regardless of patient self-reported symptoms (P = 0.043) or physicians' diagnostic classification (P = 0.018). For an EPT instrument, the Kappa coefficient was 0.67 and 1-year pulpal status findings were highly consistent (P < 0.001). Using a Doppler instrument, the Kappa coefficient was 0.85. According to the ROC curve, the AUC for EPT was 0.94, the AUC for Doppler was 1, and the optimal cut-off value was 31.55, indicating that both were superior diagnostic tools.

Conclusion

Both laser Doppler imager and EPT can be used as tools for diagnosing traumatic pulp necrosis. Doppler imaging instruments allow for a more timely and accurate assessment of pulp vitality in dental trauma. In the future, ongoing research and related training are necessary for interpretation of Doppler data.

Changes in pulp blood flow and pulp sensibility resulting from surgically assisted rapid maxillary expansion: A clinical study

INTRODUCTION

The aim of this work was to assess and compare changes in pulp blood flow (PBF) and pulp sensibility (PS) after surgically assisted rapid maxillary expansion (SARME) and rapid orthopedic maxillary expansion (OME).

METHODS

Ten patients requiring SARME and 10 requiring OME had the pulp status of their maxillary incisors and canines assessed with the use of laser Doppler flowmetry, electric pulp testing (EPT), and CO₂ snow. The SARME group was assessed at T1-S (before surgery), T2-S (after surgery, before expansion), T3-S (after surgery, at completion of expansion), and T4-S (3 months after surgery). The OME group was assessed at T1-O (before expansion), T2-O (after rapid expansion), and T3-O (3 months after expansion commencement). Relationships between PBF/PS and the procedures, assessment times, and tooth types were evaluated.

RESULTS

In the SARME group, surgery did not cause significant (P ≥0.05) reduction in PBF, maxillary expansion did cause significant (P ≤0.05) reduction in PBF, pretreatment PBF was reestablished by T4-S, and nonresponses to both EPT and CO₂ peaked at T2-S. In the OME group, rapid expansion caused significant (P ≤0.05) reduction in PBF, pretreatment PBF was reestablished by T3-O, and all teeth responded to at least 1 of EPT or CO₂ at each assessment time.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Within the study's limitations, it can be concluded that both SARME and OME induce reduction but not elimination of PBF to maxillary anterior teeth and therefore do not cause loss of pulp vitality; surgery for SARME does not significantly reduce PBF to maxillary anterior teeth, rather it is the process of maxillary expansion that significantly reduces PBF in SARME patients; and caution when using CO₂ and EPT tests alone to assess pulp status after SARME is warranted because the capacity for CO₂ or EPT to provide negative sensibility responses despite the presence of PBF was observed.

The Efficacy of Laser Doppler Flowmetry, Electric Pulp Test and Cold Test in Diagnosing Revascularization of Extrusively Luxated Immature Maxillary Incisors

Objective:

To evaluate the effect of extrusion on immature permanent tooth PBF values during a 6-month post-trauma period and to compare the accuracy of cold tests on pulp sensibility of traumatized teeth with that of electric pulp tests (EPT).

Methods:

The study group comprised of 26 extruded immature maxillary incisors in 25 trauma patients. The respective contralateral homologous teeth (n=25) were included as a positive control group. Teeth in the study group were treated by repositioning and splinting. Pulp vitality readings for traumatized and control teeth were taken with LDF, EPT and cold test on the day of splint-removal (2-3 weeks after trauma–T1) as well as 6 weeks (T2), 3 months (T3) and 6 months (T4) post-trauma. Student t and Mann-Whitney U-tests were used to compare data among groups. Statistical significance was set at P< 0.05.

Results:

LDF gave positive vitality readings (>4.5 PU) in all patients from T1 to T4 (with the exception of 1 patient at T1).

Conclusions:

LDF was able to accurately identify vitality in traumatized immature teeth even during the first few weeks following trauma, whereas conventional sensibility tests were unable to accurately recognize vitality shortly after trauma.

Effect of extracorporeal shockwave therapy (ESWT) on pulpal blood flow after orthodontic treatment: a randomized clinical trial

OBJECTIVES

The effect of non-invasive extracorporeal shockwaves on pulpal blood flow in orthodontic patients who have undergone active treatment was investigated.

MATERIALS AND METHODS

Seventy-two adult patients were enrolled in the clinical trial and allocated by block randomization to a treatment or a placebo group at a 1:1 ratio. The patients were required to be otherwise healthy. Blinding was performed for the subjects and the outcome assessor. The region of interest was the mandibular incisors and canines, which were vital, unrestored, and had experienced no trauma. The active treatment group received a single shockwave treatment with 1000 impulses at 0.19-0.23 mJ/mm(2) while the placebo group was treated with a deactivated shockwave applicator but acoustic sham. Pulpal blood flow was evaluated four times over a period of 6 months starting from the day of bracket removal, using a laser Doppler device.

RESULTS

Thirty patients were evaluated in each group. Orthodontic patients who have undergone active treatment tend to have high levels of pulpal blood flow which decrease over a period of 6 months. Pulpal blood flow did not differ significantly over 6 months between the placebo and treatment group. Shockwave treatment was associated with no significant effect in respect of tooth type, age, sex, or mean blood pressure, and had no unintended pernicious effects.

CONCLUSIONS

Extracorporeal shockwaves had no statistically significant effect on pulpal blood flow. Multiple applications of ESWT in a pathological setup may be needed in future studies to demonstrate significant differences.

CLINICAL RELEVANCE

The absence of any adverse effects justifies further principal investigations of the use of shockwave treatment in the oral cavity.

Doppler flowmetry as a tool of predictive, preventive and personalised dentistry

Periodontal lesions are considered a major problem in the global burden of oral diseases due to their high frequency and negative impact on quality of life. Periodontal inflammation is accomplished by a breakdown of microcirculatory function. Early detection of gingival microvessel dysfunction helps diagnose and prevent the progression of initial periodontal pathology. Doppler flowmetry is a useful tool in the diagnosis, monitoring, prognosis and management of periodontal patients which allows access not only of gingival blood flow but also of pulpal microcirculation. Doppler flowmeters might help to realise the ultimate target of predictive, preventive and personalised periodontology tailored with respect to the particular patient. This article highlights the main working principles of laser Doppler flowmeters and the ultrasonic Doppler flowmeters. The advances in blood flow measurement by ultrasonic flowmetry are discussed.

Parameters influencing increase in pulp chamber temperature with light-curing devices: curing lights and pulpal flow rates

This laboratory study examined the effects of curing lights with different light intensities and changing flow rate on the increase in pulpal temperature during the light curing process and the rate of the subsequent decrease in temperature after the termination of light curing. The tip of a temperature sensor was positioned on the pulpal dentinal wall of the buccal side of the maxillary premolar. Metal tubes were inserted in the palatal and buccal root of the tooth, one for water inflow and the other for water outflow. The tubes were connected to a pump to control the flow rate. The water flow rate was set to 4.2 microl/minute, 28 microl/minute or 70 microl/minute. At each flow rate, the unprepared tooth was light cured from the buccal side 1 mm from the buccalsurface, using four different curing lights. The temperature data were recorded and stored on a computer every second for three minutes. The curing lights that were used were: Astralis 10 (QTH(high), Ivoclar Vivadent), Bluephase 16i (LED(conv), Ivoclar Vivadent) and two experimental LED-curing lights (LED(exp2000), LED(exp3000), Ivoclar Vivadent). The power densities were 1200 mW/cm2, 1600 mW/cm2, 2000 mW/cm2 and 3000 mW/cm2, respectively. The curing lights, LED(conv), LED(exp2000) and LED(exp3000) were activated for 60 seconds, and the QTH(high) was activated for 30 sec- onds. The maximum intrapulpal temperature (TM) and rate of temperature change at 30 seconds after turning off the light (S(30LO)) were analyzed by two-way ANOVA with a post-hoc Tukey test (p < 0.05). The influencing factors were the flow rates and curing lights.

RESULTS

The T(MAX) ranged from 41.0 degrees C to 53.5 degrees C. There was a difference between the curing lights (p < 0.05), with LED(exp3000) > LED(exp2000) > LED(conv) > QTH(high). There was no difference in T(MAX) between the different flow rates (p > 0.05). Both the curing lights and flow rates affected the SE(30LO) (p < 0.05). The S(30LO) was LED(exp3000) < LED(exp2000) > LEDon, , QTH(high) (p < 0.05). The S(30LO) at 70 microl/minutes was higher than at 4.2 pd/minutes and 28 microl/minutes (p < 0.05).

CLINICAL IMPLICATION

Because the increase in temperature is directly related to the light intensity and exposure time, curing devices with high power density (> 1200 mW/cm2) should only be activated for a short period of time (< 15 seconds) even in teeth without cavity preparation. The flow rate had only a negligible effect on the temperature increase.

Dental pulp testing: a review

Dental pulp testing is a useful and essential diagnostic aid in endodontics. Pulp sensibility tests include thermal and electric tests, which extrapolate pulp health from sensory response. Whilst pulp sensibility tests are the most commonly used in clinical practice, they are not without limitations and shortcomings. Pulp vitality tests attempt to examine the presence of pulp blood flow, as this is viewed as a better measure of true health than sensibility. Laser Doppler flowmetry and pulse oximetry are examples of vitality tests. Whilst the prospect is promising, there are still many practical issues that need to be addressed before vitality tests can replace sensibility tests as the standard clinical pulp diagnostic test. With all pulp tests, the results need to be carefully interpreted and closely scrutinised as false results can lead to misdiagnosis which can then lead to incorrect, inappropriate, or unnecessary treatment.

A retrospective evaluation of crown-fractured permanent teeth treated in a pediatric dentistry clinic

A retrospective study was carried out on the dental trauma records of 93 patients (55 boys, 38 girls) with 129 crown-fractured teeth. The patients' average age was 9.57 years (SD 1.57), ranging between 7 and 15 years. Uncomplicated crown facture (comprising enamel-dentin) was the most observed type of injury (n = 107, 83%). Only 15 patients (16.13%) sought treatment in less than 24 h following the injury. Of 41 injured teeth (31.79%) the apices were open at the time of presentation at the clinic. The initial treatment of these injured teeth were interim restoration with acid-etch and composite (69%), Cvek amputation (2.33%), fragment reattachment (1.55%), apexification (APX, 10.07%), and root-canal treatment (RCT, 17.05%). Out of 94 teeth, which were diagnosed as vital on admittance, 23 (24.46%) later developed pulp necrosis and required APX or RCT depending on their apical status. In 66 teeth (51.16%) definitive treatment was provided with only esthetic restoration (ER), while in 15.50% and 26.68% of injured teeth ER was carried out following APX and RCT, and RCT, respectively. Definitive treatment was provided in 3-6 months for 29.45% of the injured teeth, while 27.13% and 20.16% of teeth received definitive treatment within 1-3 months and 6 months to 1 year, respectively. Type of crown-fracture, elapsed time following injury, and vitality of the tooth on admittance and pulp necrosis observed were significantly related to the total time spent for definitive treatment (P < 0.05).