Evaluation of the accuracy of intraoral scanners for complete-arch scanning: A systematic review and network meta-analysis.

OBJECTIVES: This network meta-analysis (NMA) aimed to compare the complete-arch scanning accuracy of different intraoral scanners (IOSs) to that of reference standard tessellation language (STL) files. DATA: Studies comparing the trueness and precision of IOS STL files with those of reference STL scans for different arch types (dentate, edentulous, completely edentulous with implants, and partially edentulous with implants) were included in this study. SOURCES: An electronic search of five databases restricted to the English Language was conducted in October 2021. STUDY SELECTION: A total of 3,815 studies were identified, of which 114 were eligible for inclusion. After study selection and data extraction, pair-wise comparison and NMA were performed to define the accuracy of scanning for four arch subgroups using four outcomes (trueness and precision expressed as mean absolute deviation and root mean square values). Cochrane guidelines and the QUADAS-2 tool were used to assess the risk of bias. GRADE was used for certainty assessment. RESULTS: Fifty-three articles were included in this NMA. Altogether, 26 IOSs were compared directly and indirectly in 10 network systems. The accuracy of IOSs scans were not significantly different from the reference scans for dentate arches (three IOSs), edentulous arches (three IOSs), and completely edentulous arches with implants (one IOS). The accuracy of the IOSs was significantly different from the reference scans for partially edentulous arches with implants. Significant accuracy differences were found between the IOSs, regardless of clinical scenarios. CONCLUSIONS: The accuracy of complete-arch scanning by IOSs differs based on clinical scenarios. CLINICAL SIGNIFICANCE: Different IOSs should be used according to the complete arch type.

Monolithic zirconia as a valid alternative to metal-ceramic for implant-supported single crowns in the posterior region: A systematic review and meta-analysis of randomized controlled trials.

STATEMENT OF PROBLEM: Technical complication rates of standard metal-ceramic implant-supported posterior restorations are relatively high. Whether monolithic zirconia crowns represent a more successful alternative is unclear. PURPOSE: The purpose of this systematic review and meta-analysis was to compare the clinical outcomes of posterior monolithic zirconia and metal-ceramic implant-supported single crowns. MATERIAL AND METHODS: A search was conducted in MEDLINE, Scopus, Embase, Web of Science, and CENTRAL databases for randomized controlled trials up to April 2023 with a follow-up time of at least 1 year. Restoration and implant survival and failure rates, marginal bone loss (MBL), bleeding on probing (BOP), and technical complications were analyzed by 2 reviewers. Statistical analyses were conducted using the R-statistics software program. The risk of bias was assessed by the Cochrane Risk of Bias Tool 2 (RoB 2), and the certainty of evidence by the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. RESULTS: A total of 11 out of 2030 records were identified by title and abstract, and 4 records were included after full-text analysis. The statistical analysis revealed no significant difference in MBL (MD -0.11, 95% CI: [-0.25; 0.03]), BOP (OR 0.66, 95% CI: [0.25; 1.77]), or implant failure (OR 1.30, 95% CI: [0.24; 7.08]). Monolithic zirconia presented significantly less chipping over 1 year (OR 0.17, 95% CI: [0.03; 0.99]). The chipping rate was 0% for monolithic zirconia and 7.61% for metal-ceramic. Based on a narrative review, the restoration survival rate was 97.5% in the monolithic zirconia group and 99.1% in the metal-ceramic group. CONCLUSIONS: Monolithic zirconia showed favorable short-term survival rates and had significantly less chipping over 1 year. Regarding MBL, BOP, and failure rates, both restoration types presented similar results at the 1-year follow-up.

The use of autogenous tooth bone graft is an efficient method of alveolar ridge preservation - meta-analysis and systematic review.

BACKGROUND: Ridge resorption following tooth extraction may be reduced by alveolar ridge preservation (ARP). Previous randomized clinical trials and systematic reviews have suggested that autogenous tooth bone graft (ATB) can be an effective alternative material for ARP. However, the results are heterogeneous. Therefore, our research aimed to evaluate the efficacy of ATB in ARP. METHODS: A systematic search was conducted in Cochrane Library, Embase, MEDLINE and Scopus for studies published from inception to 31 November 2021. We searched searched for randomized, non-randomized controlled trials and case series reporting on ATB use for ARP. The primary outcome was the ridge width difference pre- and post-surgery, measured in millimetres (mm) measured on CBCT (cone beam computed tomography). The secondary outcomes were the histological results. We followed the PRISMA2020 recommendations for reporting our systematic review and meta-analysis. RESULTS: The analysis included eight studies for the primary and six for the secondary outcomes. The meta-analysis revealed a positive ridge preservation effect with a pooled mean difference ridge width change of -0.72 mm. The pooled mean residual graft proportion was 11.61%, and the newly formed bone proportion was 40.23%. The pooled mean of newly formed bone proportion was higher in the group where ATB originated from both the root and crown of the tooth. CONCLUSIONS: ATB is an effective particulate graft material in ARP. Complete demineralization of the ATB tends to decrease the proportion of newly formed bone. ATB can be an attractive option for ARP. TRIAL REGISTRATION: The study protocol was registered on PROSPERO (CRD42021287890).

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.

Blood flow kinetics of a xenogeneic collagen matrix following a vestibuloplasty procedure in the human gingiva-An explorative study.

OBJECTIVES: The aim of the present study was to investigate temporal and spatial blood flow patterns following vestibuloplasty procedures using a collagen matrix (CM) to get an insight into the timing and direction of neovascularization in the CM. METHODS: Five patients were treated using a modified apically repositioned flap combined with a CM. Intraoral photographs and blood flow measurements by laser speckle contrast imaging were taken for 12 months. Thirty regions of interest in the graft and the surrounding mucosa were evaluated. The clinical parameters were assessed after 6 and 12 months. VEGF expression was analyzed in the wound fluid on days 2 and 4. RESULTS: At 6 months, the mean width of keratinized gingiva increased, but the thickness was unchanged. Scar formation was observed in all cases. Perfusion in the graft began to increase at the lateral and coronal edges and then spread concentrically toward the center. The apical side showed a significant delay in perfusion, the highest VEGF expression, and wound fluid production as well as the most abundant scar formation. CONCLUSIONS: Neovascularization occurs mainly from the lateral and coronal edges, which may limit the extent of the surgical area. Abundant scar formation may be explained by increased VEGF expression induced by prolonged ischemia in this area.

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.

Functional characterization of collaterals in the human gingiva by laser speckle contrast imaging.

OBJECTIVE: The rate of blood flow between the various areas of the gingiva in resting position and under challenge is unknown. In this study, the LSCI method was used to map spatial and temporal changes in gingival blood flow after transient compression. METHODS: Horizontal, vertical, and papilla base compressions were applied on the attached gingiva in 21 healthy patients (13 women, 8 men). LSCI was used to determine dynamic changes in regional blood flow during a five-second occlusion interval and subsequent reperfusion for twenty minutes. RESULTS: Resting blood flow in the attached gingiva apical to the papillae was higher as compared to that in the midbuccal area of the teeth. During short-term horizontal compression, ischemia was greater coronal than apical to the occlusion line. Postocclusive hyperemia was observed not only in the regions affected by ischemia but encompassed a wider area. Hyperemic response was more pronounced and prolonged in male than in female patients. CONCLUSIONS: Blood flow in the attached gingiva shows spatial differences. Our findings corroborate the apicocoronal orientation of blood circulation. Periodontal and papillary collaterals may have little role in the blood supply of the adjacent attached gingiva under physiological conditions.

Assessment of the test-retest reliability of human gingival blood flow measurements by Laser Speckle Contrast Imaging in a healthy cohort.

OBJECTIVE: The reliability of gingival blood flow measured by Laser Speckle Contrast Imaging is unknown. Our aim was to investigate the effect of factors inherent in oral mucosa measurement on intra-day and inter-day reliability. METHODS: Gingival blood flow was measured in seventy healthy subjects. First, measurements were obtained by varying the incidence angle of imaging, using a lip retractor. Second, 3 snapshots were taken with closure of the mouth in-between, and lips were retracted by a dental mirror. These were repeated 1 week later. Third, snapshots were taken either by direct view or using a mirror. Reliability was assessed based on coefficient of variation. RESULTS: Unlike retraction of the lips and the mirror, the incidence angle had an effect on mean blood flow. The coefficient of variation within a subject was 6.4% with the mouth constantly open. With retraction, the intra-session, and the inter-day coefficient of variation were 8.3% and 10.5%, respectively. The coefficient of variation was 11.9% by alternating direct and indirect imaging. CONCLUSIONS: Laser Speckle Contrast Imaging has good short- and long-term reliability regardless of lip retraction or an indirect view. This technique seems to be appropriate for the long-term clinical non-invasive follow-up of gingival microcirculation.

[Prosthodontic rehabilitation of immediately placed dental implants following soft tissue augmentation. Case report]. / EIozetes lágyszövet-korrekcióval, valamint fogeltávolítást követo azonnali implantációval végzett fogpótlás készitése. Esetismertetés.

A 68-year-old nonsmoking male patient with thin gingival biotype presented for treatment of mobile mandibular left premolars. Extraction of teeth and immediate dental implant placement has been suggested. To prevent vestibular gingival recession and insure tissue stability by increasing thickness of marginal gingiva, acellular dermal matrix allograft was applied using the coronally advanced modified tunnelling technique. Six months later premolars were extracted, immediately replaced with implants and temporary crowns. After another four months, definitive gold ceramic crowns were cemented on prefabricated titanium abutments. Due to the altered gingival biotype and application of the platform switching phenomenon no vertical bone resorption and gingival recession was recorded at 6, 12 and 24 month follow-up with a well acceptable esthetic appearance.

[Replacement of extracted tooth by means of implant-supported direct abutment. A case report]. / Implantátumba csavart direkt felépítmény alkalmazása foghiány pótlásához. Esetismertetés.

Abutment manipulation, namely repeated screwing and unscrewing may have an affect on the final marginal bone level, consequently, soft tissue position around endosseous implants. In order to maintain the crestal bone level constant and avoid the apical recession of gingiva final abutment (Direct Abutment, Astra Tech) has been connected to submerged OsseoSpeed 4.5 dental implant (Astra Tech) in position of tooth 14, immediately after second surgical exposure. Following a healing period of three weeks, impression was taken using closed tray system and plastic impression pic-up for laboratory manufacturing of zirconium crown restoration. The functional and aesthetic result of the reconstruction was highly met patient is the satisfaction. The maintenance of marginal bone level and the excellent health of the peri-implant tissues, as registered at 6-month recall, may support the benefit of the idea of final abutment insertion immediately after one-, or two-stage surgery.

The coronary effects of parathyroid hormone.

OBJECTIVE: The aim of the present study was to characterize the role of the ATP-sensitive potassium channels (K(+)(ATP)) in the coronary dilator action of parathyroid hormone (PTH). METHODS: Dose-response curves of intracoronary administrated PTH (0.15-1.33 nmol) were obtained in control phases and during continuous intracoronary administration of the K(+)(ATP) channel-selective antagonist glibenclamide (0.1-1.0 micromol/min) in dogs (n = 13). RESULTS: Increments of integrated coronary conductance (excess coronary conductance) at PTH doses of 0.15 and 1.33 nmol were 1.17 versus 0.03 ml/mm Hg (p < 0.05) and 4.03 versus 0.94 ml/mm Hg (p < 0.05) in the control versus during maximal blockade, respectively. CONCLUSION: The results indicate that the activation of K(+)(ATP) channels significantly contributes to the PTH-induced coronary vasodilation.