Acute effects of traditional and electronic cigarettes on palatal blood flow in smokers: A cross-over pilot study.

Background: Smoking is a significant health hazard and contributes to cardiovascular and pulmonary diseases. It can increase postoperative complications during oral and maxillofacial surgery due to its topical effect on the oral mucosa. New alternatives to traditional tobacco products are gaining popularity, in particular, electronic cigarettes. Objectives: This pilot study investigated the acute effects of nicotine-containing and nicotine-free electronic cigarettes on palatal blood flow (PBF), and compared their effects to traditional cigarettes. Materials and methods: 14 medically healthy volunteers (8 males, 6 females, age: 34.7 ± 7.0) were recruited for the study. All patients (N = 14) were requested to smoke nicotine-containing (ECN) and nicotine-free electronic cigarettes (EC0) and a mouthpiece (end of a traditional cigarette) as a control sham smoking blind test (BT). EC users did not smoke a traditional cigarette (TC), resulting in 10 people in the TC group. Palatal blood flow was measured by Laser Speckle Contrast Imager before, immediately after, and 15 min after the exposures. Exhaled carbon monoxide (eCO) and carboxyhemoglobin (COHb) were measured before and immediately after smoking with a piCO+ Smokerlyzer machine. Results: In all groups, no significant differences were observed in the changes of palatal blood flow between time points. Exhaled carbon monoxide and carboxyhemoglobin were significantly higher in the traditional cigarette (TC) group compared to the nicotine-containing electronic cigarette (ECN) and nicotine-free electronic cigarette (EC0) groups, both before and after the exposure (p < 0.05). Conclusion: Acute use of either traditional or electronic cigarettes may have minimal impact on palatal blood flow, but additional studies are required to clarify their impact on the mucosa.

Sex-related differences in endothelium-dependent vasodilation of human gingiva.

BACKGROUND: Sex hormones influence circulation, periodontitis, and wound healing. The aim of the study was to compare the endothelium-dependent and independent vasodilation in human gingiva in men and women. METHODS: Gingival blood flow was evaluated in twelve male and twelve female subjects with healthy gingiva and no systemic conditions after acetylcholine or nitric oxide donor (NitroPOHL). Agonists were administered into the gingival sulcus at the right secondary incisor (test site). Regional gingival blood flow (GBF) was imaged by Laser Speckle Contrast Imager from the marginal gingiva to the mucogingival junction in four consecutive regions (coronal, midway1, midway2 and apical). Blood flow was expressed in Laser Speckle Perfusion Unit (LSPU). The absolute maximal blood flow change (Dmax), the area under the blood flow curve (AUC), and the time to peak (TTP) were calculated. RESULTS: Males had higher baseline GBF than females (257 ± 18.2 vs. 225 ± 18.8 LSPU, p < 0.001). Acetylcholine and NitroPOHL significantly increased the GBF in all test regions. The Dmax after the acetylcholine was reduced apically compared to the coronal (90 ± 13 LSPU vs. 117 ± 7 LSPU, p < 0.01), but it was similar after NitroPOHL (78 ± 9 LSPU vs. 86 ± 6 LSPU, p = 0.398) in both sexes. The Dmax and AUC were higher, and the TTP was smaller in men in most regions after acetylcholine but not after NitroPOHL. CONCLUSION: In the human gingiva, the endothelium-independent vasodilation propagates without attenuation in the line of the vascular supply in both sexes. At the same time, the endothelium-dependent ascending vasodilation attenuates similarly in men and women. However, men had more pronounced endothelium-dependent vasodilation than women. Therefore, it might contribute to the increased severity of periodontal disease in men. TRIAL REGISTRATION: The study was registered with ClinicalTrials.gov on 09.06.2021 (NCT04918563).

Microvascular Reactivity of Peri-implant Mucosa in Humans: Effect of Abutment Material.

The morphology and histology of the soft tissue around the implant are different from the periodontal tissue, but the difference in the regulation of blood flow is not known. The aim of the study was to compare the resting blood flow and the vasodilatation capacity of the gingiva between implants and teeth. Twenty-six healthy volunteers with single-tooth implants were involved. The implant-borne crown was retained on either a zirconia or titanium abutment. The vasodilatation capacity of the gingiva was assessed by a postocclusive reactive hyperemia test. Blood flow was measured by a laser speckle contrast imager at the buccal gingiva of the implant-borne crown and an analog natural tooth. No significant differences in baseline gingival blood flow were observed between the different abutments and the teeth in either region. The hyperemia after compression was significantly attenuated at the zirconia abutments in all regions during the entire investigation period (20 minutes) compared to the titanium abutments and the teeth. No differences were observed between titanium abutments and the teeth. The resting microcirculation seems to be the same at implants and teeth. However, the vascular reactivity might be disturbed at the zirconia, but not at the titanium, abutment.

Revisiting the vascularity of the keratinized gingiva in the maxillary esthetic zone.

BACKGROUND: The active arterial-to-arterial collaterals are a significant factor in the prevention of ischemia and extensive tissue necrosis in the case of arterial blockage of various tissues. The present study investigates the mucogingival vasculature in the maxillary esthetic zone mucosa in human cadavers and functionally evaluates the area, which is supplied by the terminal arterioles, on the individual level. METHODS: In the human cadaver study, macroscopic arterial analyses of the anterior maxillary vestibule in 7 specimens were scrutinized by latex milk injection. The tracks of the mucosal branches in relation to the mucogingival junction were investigated. In the functional study, individual gingival blood flow (GBF) changes were measured by laser speckle contrast imaging (LSCI) in 31 young subjects with healthy gingiva before and during 30-s compressions. This was conducted with a ball-shaped condenser. The data was analyzed by the linear mixed model. RESULTS: The vertically aligned branches of the superior labial artery (SLA) divided into small, slightly deviating sub-branches near the mucogingival junction. These arteries created collateral plexuses and supplied the attached gingiva. The compression of these branches resulted in ischemia coronally with significant individual variation. The ischemia was either apico-mesial, apico-distal, or straight apical to the compression. A significant correlation was found between the ischemic area and the magnitude of the decrease in GBF (r = 0.81, p < 0.001). In males, 77% of the subjects, and 50% of the female subjects had an ischemic response in either region. The horizontal extension of the ischemic area ranged between 0.26 mm and 8.76 mm. Males had significantly higher baseline GBF and larger ischemia than females. At the base of the papilla, significant restoration of GBF was observed during compression in males, but not in females. CONCLUSION: The arcade anastomoses formed by the small arteries in the keratinized gingiva of the upper esthetic zone explain the consequences of vertical incisions. The considerable individual variations in ischemic responses might be the reason for unexpected surgical outcomes in some cases. Furthermore, there is increasing evidence that men have different vascular reactivity and/or regulation of collateral circulation than women, which may affect wound healing.

Epinephrine penetrates through gingival sulcus unlike keratinized gingiva and evokes remote vasoconstriction in human.

BACKGROUND: It has been demonstrated in non-oral tissues that the locally evoked vasoconstriction could elicit remote vasoconstriction. This study aimed to investigate the spreading vasoconstrictor effects of epinephrine in the gingiva. METHODS: Gingival blood flow (GBF) was measured by laser speckle contrast imager in 21 healthy volunteers. In group A, two wells were fabricated from orthodontic elastic ligature and placed 2 mm apically to the free gingival margin at the mid buccal line of 12 (test side) and 21 (control side) teeth. The GBF was measured in the wells and tightly apical, coronal, distal and mesial to the wells. In group B, the wells were made on the buccal surface of the same teeth, including the gingival sulcus. Four regions were selected for measurement from the gingival margin reaching the mucogingival line (coronal, midway1, midway2 and apical). After the baseline recording, 3 µg epinephrine was applied into the test, and physiological saline into the control well. The GBF was recorded for 14 min. The gingival thickness was measured with a PIROP Ultrasonic Biometer. RESULTS: In group A, the GBF did not increase or decrease after the application of epinephrine. In group B, the GBF significantly decreased in all regions of the test side and remained low for the observation period. The vasoconstriction appeared with delays in more apical regions (at min 1 in the coronal and the midway1, at min 2 in the midway2, at min 4 in the apical region). Similarly, the amount of the decrease at 14 min was the largest close to sulcus (- 53 ± 2.9%), followed by the midway1 (- 51 ± 2.8%) and midway2 (- 42 ± 4.2%) and was the lowest in the apical region (- 32 ± 5.8%). No correlation was found between GBF and gingival thickness. CONCLUSION: Epinephrine could evoke intense vasoconstriction propagating to the mucogingival junction, indicating the presence of spreading vasoconstriction in the human gingiva. The attached gingiva is impermeable to epinephrine, unlike the gingival sulcus. This trial was registered in ClinicalTrials.gov titled as Evidence of Spreading Vasoconstriction in Human Gingiva with the reference number of NCT04131283 on 16 October 2019. https://clinicaltrials.gov/show/NCT04131283.

Evidence of spreading vasodilation in the human gingiva evoked by nitric oxide.

BACKGROUND AND OBJECTIVE: Spreading vasodilation is an important means of increasing local blood flow effectively during increased metabolic demands or in case of vascular injury. Our aim was to develop a technique proving the presence of spreading vasodilation in the human keratinized gingiva. METHODS: Local vasodilation was evoked by the application of nitric oxide (NO) donor nitroglycerin into a well, fixed 2 mm above the marginal gingiva, in 20 subjects with healthy periodontal tissue. Either 1 or 8 mg/mL nitroglycerin solutions were dropped into the test well at the upper right second incisor, and saline was applied into the control well at the upper left first incisor. The gingival blood flow (GBF) was recorded for 15 minutes by a laser speckle contrast imager below the well and in the surrounding area in the mesial, distal, apical and coronal directions. Gingival thickness was measured by an ultrasonic biometer. RESULTS: Peak GBF increase was similar after 1 mg/mL and after 8 mg/mL nitroglycerin application in the well (51% ± 12% vs 42% ± 8%) and in the apical region (33 ± 9% vs 55% ± 13%). While the lower dose of nitroglycerin increased GBF only in the apical region around the well, the higher dose induced significant elevations in all surrounding regions, with apical prominence. Hyperaemia lasted 10-14 minutes in the low-dose group whereas it extended beyond the observation period in the high-dose group. Neither the baseline nor the NO-induced peak GBF were correlated with gingival thickness. CONCLUSION: The role of the direct effect of NO in the regulation of perfusion was demonstrated in the human gingiva as well as the propagation of local vasodilation to distant, especially apical areas, probably by the mechanism of flow-mediated dilation. This mechanism may have a clinical importance for flap survival or wound healing.

Assessment of Palatal Mucosal Wound Healing Following Connective-Tissue Harvesting by Laser Speckle Contrast Imaging: An Observational Case Series Study.

Postoperative complications may occur during the healing of palatal donor sites due to disturbed blood circulation of palatal tissues. Therefore in this study, blood flow was measured by Laser Speckle Contrast Imaging (LSCI) in seven patients after connective-tissue harvesting. The slope in blood-flow elevation within the first 3 days as well as time needed for maximum reperfusion were calculated. Each surgical site was assessed by clinical examination on day 3. In donor sites with secondary-intention wound healing, postoperative blood flow was elevated with significant delay compared to the surrounding tissues and to the primarily healed wound. Reperfusion time and healing score were strongly correlated (r = 0.87, P < .001), as were the slope and clinical rank (r = -0.85, P < .001). LSCI proved to be an objective method to assess individual wound-healing time and to predict the quality of wound healing.

A Novel Approach to Monitoring Graft Neovascularization in the Human Gingiva.

Laser speckle contrast imaging (LSCI) is a novel method for measuring superficial blood perfusion over large areas. Since it is non-invasive and avoids direct contact with the measured area, it is suitable for monitoring blood flow changes during wound healing in human patients. Vestibuloplasty is periodontal surgery to the oral vestibule, aiming to restore vestibular depth with simultaneous enlargement of the keratinized gingiva. In this special clinical case, a split thickness flap was elevated at the first upper premolar and a xenogenic collagen matrix was adapted to the resulting recipient bed. LSCI was used to monitor the re- and neovascularization of the graft and the surrounding mucosa for one year. A protocol is introduced for the correct adjustment of microcirculation measurement in the oral mucosa, highlighting difficulties and possible failures. The clinical case study presented demonstrated that - following the appropriate protocol - LSCI is a suitable and reliable method for following up microcirculation in a healing wound in the human oral mucosa and gives useful information on graft integration.