Factors that influence the accuracy of intraoral scanning of total edentulous arches rehabilitated with multiple implants: A systematic review.

STATEMENT OF PROBLEM: The direct digitalization of completely edentulous arches rehabilitated with multiple implants still represents a limitation regarding obtaining accurate images for prosthetic purposes. PURPOSE: The purpose of this systematic review was to present the factors that may influence the accuracy of intraoral scanning of completely edentulous arches. MATERIAL AND METHODS: This review was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria and registered with International Prospective Register of Systematic Reviews (PROSPERO) (CRD42020171021). Three examiners performed an electronic search in the Medline/PubMed, Cochrane Library, Scopus, and Web of Science databases for articles published up to January 2021. RESULTS: The electronic search resulted in 11 498 studies. After removing duplicates, 11 347 studies remained. Twelve studies were selected (10 in vitro and 2 in vivo) according to the eligibility criteria. Several factors were found to influence the performance of intraoral scanners (Carestream Dental and TRIOS, 3Shape presented the best results), the intraoral scanning technique (Promoting physical paths that join the digitization bodies can increase the accuracy of transferring the position of the implants), environmental conditions (temperature: 20 °C to 21 °C, air pressure: 750 to 760 ±5 mmHg, air humidity: 45%, angle and distance between the implants: up to 15 degrees and 16 to 22 mm, and the material of the scan body: PEEK more accurate). CONCLUSIONS: The accuracy of the intraoral scanning of completely edentulous arches is affected by factors such as the type of intraoral scanner, scanning technique, environmental conditions, angle and distance between implants, and material of the scan bodies.

Sobrevida, éxito, y efecto en la calidad de vida del tratamiento con sobredentadura mandibular en el Servicio de Especialidades Dentales, Hospital Clínico San Borja Arriarán, Chile: estudio clínico prospectivo de 11 casos. Parte I / Survival, success, and effect on the quality of life of the treatment with mandibular overdenture in the Dental Specialties Service, Hospital Clínico San Borja Arriarán, Chile: prospective clinical study of 11 cases. Part I

RESUMEN: En los hospitales públicos chilenos, los pacientes desdentados mandibulares pueden ser tratados con una Sobredentadura-Mucosoportada, Implanto-Retenida (SMIR). Para tal fin, se adaptaron los lineamientos del plan piloto "Programa de Prestaciones Valoradas. Odontología 2012 Ministerio de Salud", en ausencia de una Guía Ministerial. El objetivo de esta serie de casos fue evaluar si la implementación y adaptación del plan piloto del tratamiento con SMIR mejoró la calidad de vida de los pacientes. Se evaluaron sobrevida, éxito implantario, e impacto en la calidad de vida. Los resultados indican una sobrevida y éxito implantario del 100% y una mejora de la calidad de vida. Conclusión: el tratamiento con SMIR mejora la calidad de vida de los pacientes, en el servicio público.

ABSTRACT: In Chilean public hospitals, patients with Complete Edentulous Mandible are treated with Implant-Retained and Mucosa-supported Overdenture (IRMO). For this purpose, the guidelines of the pilot plan "Valued Benefits Program in Dentistry 2012, Ministry of Health" have been adapted. The aim of this study was to evaluate whether these adapted protocols have been successful. We measured implant survival and success, and impact on quality of life with OHIP-14 criteria. Results indicate 100% implant survival and success and improved quality of life. Conclusion: IRMO improves patients' quality of life in public services.

Stress evaluation of different implant lengths on atrophic edentulous mandibles with fixed full-arch implant-supported prosthesis: a finite element analysis.

Finite element analysis was used to compare the effect of different implant lengths on atrophic mandible with full-arch fixed prostheses. Four models were constructed with different implant lengths: 4, 6, 8 and 10 mm. A 100-N occlusal load was applied. The stress at the bone level, implant, and prosthetic components were obtained. Similar behavior was observed for all groups, except for 4 mm, which showed more discrepant values ​​for all prosthetic components. Although longer implants presented better biomechanical behavior, the 4 mm implant seems to be a viable alternative for severely atrophic mandibles, however, further studies need to be carried out.

Denture scanning technique for computer-guided implant-supported restoration treatment of edentulous patients.

The traditional protocol for guided surgery in a completely edentulous patient is time-consuming, requiring the fabrication of a radiographic guide and a dual cone beam computed tomography (CBCT) scan. Using intraoral scanners to scan the edentulous ridge and the existing denture has been advocated to simplify the process. This technique offers a versatile, precise, and predictable method for the digital planning workflow in edentulous patients for either a fixed or removable restoration. In addition, this approach can help improve the quality of the guide produced by reducing CBCT artifacts associated with the existing denture, as well as capture the soft-tissue contour to further improve the fit of the surgical guide.

Clinical outcome of removable prostheses supported by mini dental implants. A systematic review.

INTRODUCTION: For many years, edentulous patients have had no other option than conventional dentures to reestablish their oral function. To avoid the need for bone graft surgery, some professionals have suggested the use of mini dental implants (MDIs) to support prostheses. The MDIs are narrow implants, ranging approximately from 1.8 to 2.9 mm in diameter. Recently, the promising results of mini implants regarding osseointegration and patient satisfaction have led clinicians to accept them as a definitive treatment option. OBJECTIVE: Therefore, the proposition of this systematic review was to assess information on the outcomes of MDIs supporting removable prostheses. METHODS: The PubMed and Cochrane databases were searched for articles published before September 2017, which yielded a total of 774 studies for analysis. After exclusion and inclusion criteria, 22 prospective studies were included in this systematic review. RESULTS: Most mini implants were placed in a flapless single-stage surgery and loaded immediately. Most studies reported failures in the first year and prosthetic complications. The mean survival rate of the selected studies was 95.6%, and mean follow-up was 22.8 months. CONCLUSION: The MDI-supported removable prostheses successfully improved patients' chewing and speaking ability, quality of life, and satisfaction, suggesting that MDIs are a viable and safe option to support removable prostheses in the mandibular arch.

Bilateral balanced occlusion compared to other occlusal schemes in complete dentures: A systematic review.

No consensus has been reached regarding the best occlusal scheme for making complete dentures. Thus, the purpose of this systematic review was to compare bilateral balanced occlusion (BBO) with other occlusal schemes (canine guidance, lingualised occlusion and zero degree) in complete dentures. The schemes were compared in terms of quality of life/satisfaction and masticatory performance. Two independent reviewers performed a comprehensive search of studies published in or before October 2017 using the PubMed/MEDLINE, Scopus and Cochrane Library databases. The search was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The focused question was: "In conventional complete denture, is BBO better than lingualised occlusion, canine guidance and zero degree in terms of quality of life, patient satisfaction and masticatory performance/muscle activity?" Seventeen studies were selected for analysis. In total, there were 492 patients with a mean age of 64.78 years and a mean follow-up duration of 2.96 months (range: 1-6 months). All studies compared BBO with the other occlusal schemes. Eleven studies evaluated the influence of the occlusal scheme designs on quality of life and satisfaction, and 8 studies evaluated masticatory performance and muscle activity between BBO and the other occlusion schemes. The present systematic review indicated that BBO does not confer better quality of life/satisfaction or masticatory performance and muscle activity. Thus, lingualised occlusion can be considered a predictable occlusal scheme for complete dentures in terms of quality of life/satisfaction and masticatory performance, while canine guidance can be used to reduce muscular activity.

Maximum Bite Force of Edentulous Patients before and after Dental Implant Rehabilitation: Long-Term Follow-Up and Facial Type Influence.

PURPOSE: (1) To evaluate patients' long-term maximum bite force (MBF) after rehabilitation with mandibular implant-supported prosthesis, (2) to assess the influence of facial pattern in MBF, and (3) to evaluate the relation between the dominant chewing side and MBF. MATERIALS AND METHODS: Twenty-nine patients were selected. Pre- (T0) and immediate post-rehabilitation (T1) data of MBF were collected. In a follow-up visit 3 to 5 years after rehabilitation (T2), 24 patients participated. The patients were asked about dominant chewing side, and facial pattern was obtained by the initial lateral radiographs. RESULTS: There was statistically significant increase in MBF in T1 - T0 = 5.4 ± 4.3 kgf, T2 - T1 = 5.5 ± 6.0 kgf. There was no statistically significant difference in MBF considering facial type, brachyfacial (T0 = 4.4, T1 = 10.7, T2 = 17.6 kgf), mesofacial (T0 = 4.1, T1 = 9.7, T2 = 16.5 kgf), and dolichofacial (T0 = 3.4, T1 = 7.9, T2 = 12.6 kgf). CONCLUSIONS: There was no statistically significant relation between MBF and the dominant chewing side. It can be concluded that mandibular rehabilitation with dental implants improves MBF independent of the facial pattern and dominant chewing side.

Incorporation and Remodeling of Bone Block Allografts in the Maxillary Reconstruction: A Randomized Clinical Trial.

BACKGROUND: Severe alveolar atrophy often presents a challenge for the implant surgery. The significant lack of bone in the alveolar ridges may compromise the final restorations both from the aesthetic and functional standpoints. OBJECTIVES: To evaluate the behavior of bone block allografts for the maxillary augmentation and to investigate its incorporation, remodeling, and implant survival rates in two different healing time points. MATERIAL AND METHODS: Sixty-six consecutive patients (52 female/14 male, mean age: 57.95 ± 9.06 years old), presenting 113 atrophic alveolar ridges underwent maxillary augmentation with fresh-frozen allogeneic bone blocks from tibia. Patients were randomly assigned in two groups: Group 1-patients who would wait 4 months for implant placement after grafting, and Group 2-patients who would wait 6 months. Events of infection, suture dehiscence or mucosal perforation were recorded. Cone-beam computed tomography scans were compared volumetrically between the time of the grafting surgery and reentry procedure after incorporation. Biopsies were collected and subjected to histological, histomorphometric and immunehistochemical analysis. RESULTS: A total of 305 implants were placed in the reconstructed sites. The mean resorption rate in Group 1 (13.98% ± 5.59) was significantly lower than Group 2 (31.52% ± 6.31). The amount of calcified tissue, newly formed bone and remaining graft particles demonstrated no difference between groups. The samples showed evident immunolabeling for the podoplanin protein in both groups. The implants cumulative survival rate was 94.76%. CONCLUSIONS: The findings of the present study indicate that there is a significant difference regarding the resorption of the grafts when waiting 4 or 6 months before placing the implants, even though no difference was found in the histological, histomorphometric, and immunohistochemical features. Both 4-month and 6-months healing times are suitable for the implant placement.

Stability and Crestal Bone Behavior Following Simultaneous Placement of Multiple Dental Implants (Two or More) with the Bone Splitting Technique: A Clinical and Radiographic Evaluation.

PURPOSE: The present study aimed to measure the implant stability quotient (ISQ) values at three different time points after surgical procedures and crestal bone behavior in multiple implants (two or more) installed simultaneously with the bone splitting technique. MATERIALS AND METHODS: For this study, 45 patients with different edentulous areas in the maxilla were selected, and a total of 114 dental implants were installed. Implant stability was measured by resonance frequency analysis immediately following implant placement to assess immediate stability (time 1) and stability at 90 days (time 2), and 150 days (time 3). Crestal bone height was measured in peri-apical radiographs at 90 and 150 days after implantation in relation to each implant shoulder, given that the implants were installed at the level of the crestal bone. RESULTS: Six implants were not osseointegrated. Overall, the means and standard deviations of the ISQ values were 60.3 ± 4.94 (95% confidence interval [CI], 44-69) at baseline, 66.6 ± 5.28 (95% CI, 49-75) at 90 days, and 72.1 ± 4.28 (95% CI, 59-79) at 150 days (p < 0.0001). The mean marginal bone loss of the implants was 1.11 ± 0.61 mm on the mesial side and 1.17 ± 0.61 mm on the distal side at time 2, and 1.73 ± 0.68 mm on the mesial side and 1.79 ± 0.70 mm on the distal side at time 3. A strong positive correlation between implant stability and bone loss was detected (p < 0.0001). CONCLUSIONS: Within the limits of this study, the bone splitting technique with simultaneous implant installation exhibited a good success rate with respect to the osseointegration index but requires attention with respect to crestal bone behavior.

Electromyography evaluation of masseter and temporalis, bite force, and quality of life in elderly patients during the adaptation of mandibular implant-supported overdentures.

OBJECTIVES: The aim of this study was to investigate the outcomes of the installation of two implant-supported overdentures until such treatment is complete. Although this treatment is well established in the literature, there are no studies comparing what happens to muscles and the quality of life (QoL) of patients during the treatment. METHODS: We selected 13 completely edentulous patients, according to inclusion and exclusion criteria, to rehabilitate with mandibular overdentures retained by two dental implants and a complete denture as antagonists. We evaluated the efficacy of the treatment and its evolution in five steps: (i) initially, with the old complete dentures, (ii) after the implants' placement with the mandibular prosthesis relined, (iii) after the placement of the healing abutments, (iv) after the installation and adaptation of new prostheses, and (v) after a 3-month follow-up period. At each stage, we evaluated patients via temporal and masseter electromyography (EMG), molar and incisive bite force, and QoL. RESULTS: The results for EMG found a decrease in muscle activity during rest, the mastication of raisins, and lateral movements when the overdentures were installed. For the bite force and QoL, there was a gradual improvement from the placement of the healing abutments period (P Ë‚ 0.05), which was sustained until the follow-up. CONCLUSIONS: Comfort and stability improved during the treatment, demonstrated by the QoL and bite force results. These results are positive for elderly patients who might refuse an implant-supported overdenture due to treatment length.

Bone Remodeling Around Implants with External Hexagon and Morse-Taper Connections: A Randomized, Controlled, Split-Mouth, Clinical Trial.

OBJECTIVES: To evaluate clinical, radiographic, microbiologic, and biomechanical parameters related to bone remodeling around implants with external hexagon (EH) and Morse-taper (MT) connections. MATERIALS AND METHODS: Twelve totally edentulous patients received four custom-made implants in the interforaminal region of the mandible. Two of those implants had the same macroscopic design, but different prosthetic connections. All patients received an immediate implant-supported prosthesis. Clinical parameters (periimplant probing pocket depth (PPD), modified gingival index (mGI), and mucosal thickness (MTh)) were evaluated at 12 months follow-up. The distance between the top of the implant and the first bone-to-implant contact (IT-FBIC) was evaluated on standardized digital peri-apical radiographs acquired at 1, 3, 6, and 12 months follow-up. Samples of the subgingival microbiota were collected 1, 3, and 6 months after implant loading and used for the quantification of Tanerella forsythia, Porphyromonas gingivalis, Aggragatibacter actinomycetemcomitans, Prevotella intermedia, and Fusobacterium nucleatum. Further, 36 computerized-tomography based finite element (FE) models were accomplished, simulating each patient under three loading conditions. RESULTS: The evaluated clinical parameters were equal for EH and MT implants. Mean IT-FBIC was significantly different between the tested connections (1.17 ± 0.44 mm for EH, and 0.17 ± 0.54 mm for MT, considering all evaluated time periods). No significant microbiological differences could be observed between tested connections. FE analysis showed a significantly higher peak of equivalent (EQV) strain (p = 0.005) for EH (mean 3,438.65 µÎµ) compared to MT (mean 840.98 µÎµ) connection. CONCLUSIONS: Radiographic periimplant bone loss depends on the implant connection type. MT connections showed less periimplant bone loss, compared to EH connections.

Analysis of the blood supply to the post-fracture edentulous mandible: study by colour Doppler sonography.

PURPOSE: This study assessed the arterial blood supply to the mandible of edentulous patients treated for mandibular fractures using colour Doppler ultrasound. METHODS: The blood supply of edentulous patients surgically treated for mandibular fractures (group A) and edentulous fracture-free individuals (group B) was assessed. Only the fractured sides were evaluated in the first group (N = 17), whereas each side was evaluated in the second group (N = 20). The arterial flow of six sites was assessed. The systolic-peak maximum velocity (SPV), final diastolic velocity (FDV), resistive index (RI), pulsatility index (PI), acceleration and flow direction of each artery were obtained. Additionally, the presence of local vascular obstructive factors was evaluated. The differences between groups were analysed using the Kruskal-Wallis test, which was complemented by the Mann-Whitney test, for correlations between the degree of alveolar atrophy and the study factors (p < 0.050). RESULTS: There was a significant decrease in the flow of certain arteries, especially the submental (SPV, p = 0.007, PI, p = 0.022, and acceleration, p = 0.015), in the fracture group. The facial artery in both groups showed lower values related to local obstructive factors (SPV, p = 0.001, FDV, p = 0.040, and PI, p = 0.030). The submental artery flow was higher (SPV, p = 0.006, and FDV, p = 0.009) in non-atrophic individuals. CONCLUSIONS: There was a decreased flow mainly in the submental artery, but there were no cases of major vascular injury in edentulous patients treated for mandibular fractures.

Immediate loading of implants in the edentulous mandible: a multicentre study.

PURPOSE: The aim of this prospective study was to investigate the two-year outcomes following immediate loading of mono-cortically engaged implants. MATERIALS AND METHODS: Thirty healthy mandible edentulous patients with an average age of 67.3 years and presenting with sufficient bony ridge at the mandible symphysis were included in the study. Four Astra Tech, Ti-Oblast® implants were installed between the mental foramina using the mono-cortical anchorage technique. The primary stability of the implants was assessed by resonance frequency analysis (RFA). After uni-abutments were placed, a temporary bridge was constructed and fixed the same day. The definitive bridges were installed 6 weeks after implant surgery. Five of 120 placed implants were lost in four patients during the first 6 weeks and these patients were excluded from the follow-up. The changes in marginal bone level (n = 20) were evaluated in Brazilian and Swedish groups at baseline, 6 weeks, 6 months, 12 months and 24 months. The RFA (n = 30) was evaluated at baseline, 6 weeks, 6 months, 12 months and 24 months postoperatively. RESULTS: Compared with baseline measurements, the postoperative values for marginal bone level (6 weeks, 6 months, 12 months and 24 months) were significantly reduced (p < 0.05), while no differences were observed in the RFA analysis (12 months and 24 months). CONCLUSIONS: The immediate loading of mono-cortically engaged implants in the edentulous mandible is safe and predictable and implant stability remains excellent after 2-year follow-up.

A histological study of non-ceramic hydroxyapatite as a bone graft substitute material in the vertical bone augmentation of the posterior mandible using an interpositional inlay technique: A split mouth evaluation.

The aim of this study was to compare the influence of graft material (non-ceramic hydroxyapatite versus autologous bone) on bone behaviour and perform a resonance frequency analysis of implants placed in augmented sites to evaluate stability. For this study, 11 patients with bilateral edentulous areas in the mandibular posterior region were selected. Alveolar augmentation osteotomies were bilaterally (split mouth design) performed. In one hemiarch, the space generated by the osteotomy was grafted with an interpositional intra-oral autologous bone graft (control group). In the other hemiarch, the space generated by the osteotomy was grafted with an interpositional non-ceramic hydroxyapatite (ncHA) (test group). The groups were randomized. After 6 months of healing, a bone sample was retrieved from each side for histological evaluation using a trephine drill that was 2-mm in internal diameter. The implant stability quotient (ISQ) was measured by the resonance frequency immediately following implant placement at baseline and after 6 months of follow-up. Good incorporation of the graft was observed in both groups; however, in the test group, a residual-grafted material was observed. Bone density and marrow spaces were similar between groups. Correlations between the ISQ values and the histometric variables were not observed (p>0.05). The results of this trial suggest that both intra-oral autologous bone and ncHA may be elected as interpositional grafting materials to vertically augment posterior atrophic mandibles.

Implantes de carga imediata em pacientes edêntulos totais: fatores de risco

A implantodontia como modalidade terapêutica e restauradora tem-se mostrado bastante eficaz e com altas taxas de sucesso. Algumas modificações e evoluções do protocolo idealizado inicialmente por BRANEMARK (1977) surgiram proporcionando a resolução de casos específicos com período de tempo abreviado e a obtenção de resultados de curtos prazo...

Electromyographic analysis of the upper and lower fascicles of the orbicular oris muscle, in edentulous patients, before and after complete denture implantation.

The orbicular oris muscle, including its upper and lower fascicles, the alveolar processes and dental arches, constitute a complex morpho-functional system, located in the lower third of the face, which is very important for the clinical determination of the occlusal vertical dimension. Any alteration of this system, as in the case of edentulous patients, might produce esthetic problems and alterations in the muscular tonicity. This study was aimed to evaluate the electromyographic behaviour of that musculature in patients while pronouncing the syllables PAH, BAH, MAH, SAH, FAH, VAH, MEE, and the word MISSISSIPPI. Edentulous patients were submitted to electromyographic tests under two clinical conditions: before and after the implantation of complete dentures. A K6-I EMG Light Channel Surface Electromyograph was utilized (Myo-tronics Co. Seattle, WA, USA). The Analysis of Variance, with 3 sources of variation (Syllables, Muscles and Clinical Conditions) and 12 repetitions, indicated statistically significant differences in the pronunciation of the different syllables. For the Muscles factor, the analysis revealed higher electromyographic readings in the lower fascicle of the orbicular oris muscle, as compared with those of the upper fascicle. The comparison among the Clinical Conditions indicated higher electromyographic values for the edentulous condition (i.e., before complete denture implantation), as compared to those recorded after denture implantation.