Repositioning accuracy of the implant- and abutment-level prosthetic components used in conventional and digital workflows.

OBJECTIVES: To evaluate the repositioning accuracy of the implant- and abutment-level impression components (impression abutments and implant scan bodies) and implant abutments (with and without anti-rotational hex index); also, to estimate the tightening torque influence on the positional stability of abutments. METHODS: Seven types of prosthetic components (n = 7) [impression pick-up copings (PC), implant scan bodies (ISB), non­hex and hex titanium base implant abutments (TB H and TB NH), multi-unit impression copings (MU PC), multi-unit implant scan bodies (MU ISB), and multi-unit caps (MU C) (Medentika GmbH)] were tested. For repositioning accuracy tests a coordinate measuring machine (CMM) was used. During assembly 15 Ncm torque for all components was applied. After measurement, only hex and non­hex abutments were torqued to 25 Ncm and their coordinates were again recorded to assess torque influence. The procedure was repeated 7 times for each component. Linear and 3D deviations, angulation to the vertical axis, and axial rotation were calculated. The Kruskal-Wallis test was used to compare the measurements between the groups. A post-hoc test (Mann-Whitney U test) was used for pairwise comparison to determine the influence of the torque (α=0.05). RESULTS: Implant- and abutment-level components used for digital scans showed different positional discrepancies compared to ones used for conventional impressions and ranged from 10 to 37 µm. Hex abutments demonstrated statistically significantly lower 3D deviations (4.4 ± 7.1 µm) compared to non­hex abutments (8.7 ± 6.1 µm). Torque influence was significantly lower for hex abutments than for non­hex abutments. CONCLUSIONS: Repositioning inaccuracies were found in all implant- and abutment-level impression components (impression abutments and implant scan bodies) and all abutments (with and without anti-rotational hex index) tested. Final tightening of the components could cause further positional discrepancies. CLINICAL SIGNIFICANCE: The misfit of the prosthetic components used in conventional and digital workflows stays in the clinically acceptable range. Even when multiple connections and disconnections on the track of the laboratory preparation is needed, it should not have a negative influence for single teeth reconstructions. However, in the complex cases with multiple implants, repetitive repositioning of the prosthetic components may lead to the accumulation of vertical, horizontal and rotational errors leading to the clinical problems with the passive fit of the final framework.

Minimally Invasive Treatment of Lateral Incisors with Guided One-Piece or Two-Piece Titanium-Made Narrow Diameter Implants: A Retrospective Comparative Study with Up to Two Years Follow-Up.

Restoring teeth with dental implants has become the gold standard in recent years, especially in the esthetic zone. However, limited amount of available bone as well as limited interdental space in the anterior zone may create problems for implant treatment. Narrow diameter implants (NDI) may be a treatment option to resolve the above-mentioned limitations and providing minimally invasive implant therapy without additional regenerative procedures. In this retrospective study, a comparison of clinical and radiographic outcomes between one-piece and two-piece titanium-made NDIs was done with the follow-up of two years after loading. Twenty-three NDI cases were analyzed, 11 in the one-piece implant group (group one) and 12 in the two-piece implant group (group two). The outcomes were implant and prosthetic failures, any complications occurred, peri-implant bone level changes, and as well as the Pink Esthetic score. No implant or prosthetic failures, as well as, no complications were reported at the two-year follow-up examination. At the same time the marginal bone loss was 0.23 ± 0.11 in the group one and 0.18 ± 0.12 in the group two. Difference was not statistically significant (p = 0.3339). The Pink Esthetic Score, recorded two years after definitive loading, was 12.6 ± 0.97 in the group one and 12.2 ± 0.92 in the group two, with no statistically significant difference between groups (p = 0.3554). With the limitations of the present study, including the small sample size and short follow-up, it is possible to conclude that either one and two-piece NDI can be successfully used to restore lateral incisors with comparable results within the two years of follow-up.

A Rare Case of Front Mandible Orthokeratinized Odontogenic Cyst - Surgical Management with Preventive Rigid Osteosynthesis.

PURPOSE: Cysts and other intrabony lesions can grow asymptomatic until being diagnosed by occasionally done radiologic examination. Missing tooth and malposition of adjacent teeth should induce clinicians to perform X-Ray diagnostic. METHODS: A 37-year-old, male patient was admitted with a hopeless tooth 36, to be extracted and replaced with an implant. Clinical examination revealed also missing one of lower incisors and malposition of remaining lower incisors. Cone-beam computed tomography revealed horizontally impacted lower incisor surrounded by bone defect -15 × 20 × 8 mm with the bone thickness remaining only 3.5 mm in the narrowest area. The basis on strong masticatory muscles and low thickness of bone after surgical removal of tooth and lesion, prophylactic osteosynthesis was planned. To explain the surgery to the patient model of the mandible was 3D printed. RESULTS: Two treatment plans were presented to the patient: 1. custom plate production according to the bone defect and the shape of remaining bone and 2. choosing a standard plate and adjusting it on the 3D printed model. Costs of the material were 10 times higher in a custom solution. Plan 2 was then accepted. 1.2 mm straight plate was prebend on the model and sterilized. Lesion and impacted tooth were removed in local anesthesia. Prepared plates were fixed. CONCLUSIONS: In the presented case custom 3D printed osteosynthesis plate was about 10 times more expensive compared to the standard osteosynthesis plate used. 3D printing of bone model may be helpful for prebending chosen standard plate and planning the surgery.

Artificial Intelligence Application in Assessment of Panoramic Radiographs.

The aim of this study was to assess the reliability of the artificial intelligence (AI) automatic evaluation of panoramic radiographs (PRs). Thirty PRs, covering at least six teeth with the possibility of assessing the marginal and apical periodontium, were uploaded to the Diagnocat (LLC Diagnocat, Moscow, Russia) account, and the radiologic report of each was generated as the basis of automatic evaluation. The same PRs were manually evaluated by three independent evaluators with 12, 15, and 28 years of experience in dentistry, respectively. The data were collected in such a way as to allow statistical analysis with SPSS Statistics software (IBM, Armonk, NY, USA). A total of 90 reports were created for 30 PRs. The AI protocol showed very high specificity (above 0.9) in all assessments compared to ground truth except from periodontal bone loss. Statistical analysis showed a high interclass correlation coefficient (ICC > 0.75) for all interevaluator assessments, proving the good credibility of the ground truth and the reproducibility of the reports. Unacceptable reliability was obtained for caries assessment (ICC = 0.681) and periapical lesions assessment (ICC = 0.619). The tested AI system can be helpful as an initial evaluation of screening PRs, giving appropriate credibility reports and suggesting additional diagnostic methods for more accurate evaluation if needed.

Five-Year Prospective Study on Implant Failure and Marginal Bone Remodeling Expected Using Bone Level Implants with Sandblasted/Acid-Etched Surface and Conical Connection.

OBJECTIVE: The purpose of the present prospective, case-series study was to report implant survival rate and marginal bone remodeling expected 5 years after loading using dental implants placed in daily practice. MATERIALS AND METHODS: This research was designed as an open-cohort, prospective, case-series evaluation. Any partially or completely edentulous patient, scheduled to receive at least one bone level implant, was considered eligible for this study. Primary outcome measurements were: implant and prosthetic cumulative survival rate and any complications experienced up to the 5-year follow-up. Secondary outcome measures were: thickness of gingival biotype, implant insertion torque, implant stability quotient, and marginal bone loss (MBL). RESULTS: Ninety consecutive patients (34 males and 56 females, aged between 24 and 81 years old [mean: 53.2 ± 15.4]) with 243 inserted implants were followed for at least 5 years after loading (mean: 65.4 ± 3.1 months; range from 60 to 72). At the 1-year follow-up, no drop-outs were recorded, but 17 patients (18.9%) with 18 restorations (12.6%) delivered on 34 implants (14%) were lost at the 5-year examination. At the 5-year follow-up examination, six implants lost osseointegration (97.5%). In the same period, four prostheses failed (97.2%). Five complications were reported in five different patients (prosthetic success rate was 96.5%, at patient level). Five years after loading, the mean MBL was 0.41 ± 0.30 mm. The difference from the 1-year data was 0.04 ± 0.19 mm. A statistically significant higher MBL was found for smokers, and patients with thin gingival biotype. The mean implant insertion torque was 42.9 ± 4.8 Ncm (range from 15 to 45 Ncm). Two-hundred and three implants (83.5%) were inserted with an insertion torque ≥35 and ≤45 Ncm. CONCLUSIONS: High implant survival and success rate could be expected with stable marginal bone remodeling up to 5 years after loading. Smoking and thin tissue biotype were the most important variabilities associated with higher MBL. Further research studies are needed to confirm these results.

Accuracy of surgical templates with and without metallic sleeves in case of partial arch restorations: A systematic review.

INTRODUCTION: The aim of the present systematic review was to evaluate whether there were any differences in the three-dimensional accuracy and the implant survival rate of implants placed using computer-assisted planning and surgical templates with or without metallic sleeves. SOURCES: This systematic review was written according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered to the PROSPERO (International prospective register of systematic reviews) database. STUDY SELECTION: PICOS (population, intervention, control, outcomes, and studies) question was assessed, too. Search strategy encompassed the online (MedLine) literature from 1990 up to December 2020 published in English, and evaluating the accuracy of surgical templates with and without metallic sleeves in partial or complete patients. Only in vivo, randomized controlled trial and observational studies were included. Quality assessment of selected full text articles was performed according to the CONSORT (CONsolidated Standards of Reporting Trials) and STROBE (Strengthening the Reporting of Observational studies in Epidemiology) statement guidelines, respectively. For data analysis, the three-dimensional accuracy and the overall implant survival rate was calculated and compared between implants placed using surgical templates with or without metallic sleeves. DATA: A total of 12 articles fulfilled the inclusion/exclusion criteria. Data from 264 patients with 614 implants were subjected to quality assessment (templates with metallic sleeves: 279 implants and 136 patients; templates without metallic sleeves: 335 implants and 128 patients). In all the three deviation parameters (angular, vertical, and horizontal), the differences in average accuracy were noticed (angular 2.33° ± 2.01° versus 3.09° ± 1.65°, vertical: 0.62 ± 0.36 [mm] versus 0.95 ± 0.42 [mm]; and horizontal: 0.62 ± 0.41 [mm] and 1.11 ± 0.57 [mm]. No differences was found regarding overall implant survival rate (0.4891). CONCLUSIONS: With the limitations of the present study, the surgical templates without metallic sleeves demonstrated high level of accuracy in all the three-dimensional measurements, when used to rehabilitate partially edentulous patients. Further randomized controlled trials, reporting according to the CONSORT guidelines are needed to confirm that the differences in accuracy depended on the type of used templates.

Minimally Invasive Transcrestal Sinus Floor Elevation Procedure in Severely Atrophic Ridge: A Case Report.

Typically, the greater the atrophy of the process, the more extensive and invasive the sinus floor elevation procedure is. This case of a 39-year-old man demonstrates a minimally invasive hydrostatic sinus lift from 1.7-mm height process in the site of lost tooth No. 16. Using a small flap, safe drills for a crestal approach diameter of 2.8 mm, 2 mL of saline solution under pressure of a syringe plunger, and 1 g of particulated bovine xenograft, a 14-mm height and 12-mm width sinus floor elevation was obtained. The implant was placed with a torque of 30 Ncm, and a healing cap was attached. Despite the very difficult conditions, the presented method not only resulted in a very good therapeutic effect but also reduced the number of procedures and time necessary for complete rehabilitation of the patient. The total treatment time to the final crown delivery was 6 months.

Comparison of Dental Stone Models and Their 3D Printed Acrylic Replicas for the Accuracy and Mechanical Properties.

This study was conducted to test possibilities of application of 3D printed dental models (DMs) in terms of their accuracy and physical properties. In this work, stone models of mandibles were cast from alginate impressions of 10 patients and scanned in order to obtain 3D printed acrylic replicas. The diagnostic value was tested as matching of model scans on three levels: peak of cusps, occlusal surface, and all teeth surfaces. The mechanical properties of acrylic and stone samples, specifically the impact strength, shore D hardness, and flexural and compressive strength were investigated according to ISO standards. The matching of models' surfaces was the highest on the level of peaks of cusps (average lack of deviations, 0.21 mm) and the lowest on the level of all teeth surfaces (average lack of deviations, 0.64 mm). Acrylic samples subjected to mechanical testing, as expected, showed higher mechanical properties as compared to the specimens made of dental stone. In the present study we demonstrated that 3D printed acrylic models could be ideal representatives in the case of use as a diagnostic tool and as a part of medical records. The acrylic samples exhibited not only higher mechanical properties, but also showed better accuracy comparing to dental stone.

Repeatability of Freehand Implantations Supported with Universal Plastic Sleeves-In Vitro Study.

Repeatability and precision are major factors which have an influence on final implant treatment results. The aim of this study was to evaluate the repeatability of freehand implant procedures assisted with special plastic sleeves which are placed on the drill to guarantee the proper mesiodistal distance from the landmark's surface. Patient data required for implant treatment, including images of mandibles from CBCT scans and virtual models of soft tissues and teeth, were used to prepare complete virtual models of patient clinical conditions. The models were saved as STL files and 3D printed in five copies. Drilling procedures were done at positions 37, 46 and 47. Each model was scanned with pins in the osteotomies and compared using digital aligning of the models' surfaces. The average deviation was -1.38 ± 1.4 mm. Average deviations on guide pins placed at position 37 were -0.46 ± 0.59 mm, at position 46 were -1.46 ± 0.88 mm (landmark's surface of both: distal tooth's surface), and at position 47 were the highest: -2.69 ± 1.62 mm (landmark's surface: surface of plastic sleeve). The following conclusion was drawn: Using universal plastic sleeves could improve implant procedure precision especially in the case of partially edentulous patients.

Incidence of abnormalities in temporomandibular joints in a population of 1,100 urban and rural patients lacking teeth and other parafunctions in 2003-2008. An international problem.

INTRODUCTION AND OBJECTIVE: A hectic lifestyle and everyday stress are direct causes of parafunctions. The objective of the presented study was to examine the relation of sleep disorders, distant pain symptoms, symptoms of pathological tooth wear in rural and urban patients with parafunctions. MATERIALS AND METHODS: The patient group consisted of 836 women and 274 men aged 9-82, and divided into groups taking into account the following criteria: number of patients in certain age groups, number of women and men, place of residence, presence of missing teeth problem, presence of occlusal and non-occlusal parafunctions, symptoms of tooth wear, distant pain symptoms, and sleep disorders. RESULTS: 354 (31.89%) of the patients came from the rural environment. Distant pain symptoms were more frequent in patients performing parafunctions than in those who did not perform parafunctions (n = 1110, RR = 1.10, CI = from 1.04 to 1.16). Sleep disorders were more frequent in patients performing parafunctions than in those who do not perform parafunctions (n = 1110, RR = 1.06, CI = from 1.00 to 1.12). Symptoms of pathological tooth wear were more frequent in patients performing parafunctions than in those who did not perform parafunctions (n = 1110, RR = 1.08, CI = from 1.02 to 1.13). CONCLUSIONS: It is extremely important (as it is international problem) to introduce prophylactic care to prevent the occurrence of parafunctional activity in patients from the rural environment. Parafunctions, therefore, should be taken into account in the diagnosing procedure of such disorders and pathological symptoms as pathological tooth wear, sleep disorders, cervicalgia, neck myalgia, shoulder girdle myalgia, and dorsalgia.