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Purpose: To assess the amount of excess cement and the retentive strengths of two different cementation techniques (conventional cementation and practice abutment) using copings fabricated with three different cement thicknesses (20 µm, 35 µm, and 50 µm). Materials and methods: Thirty zirconia copings were fabricated on screw retained abutments and randomly divided into three equal groups (n = 10) according to the cement thickness (20 µm, 35 µm, and 50 µm). Each group was cemented with tow cementation techniques. Cementation was performed with provisional cement (Temp-Bond). In the conventional cementation technique, cement was applied until each coping was approximately half filled, and the copings were subsequently placed on the implant-abutment assembly. Then, the copings were cleaned and cemented using the practice abutment cementation technique to remove excess cement prior to the process. Each technique was performed using copings with three different cement thicknesses (20 µm, 35 µm, and 50 µm). The specimens with the cemented copings were weighed on a high-precision analytical balance before and after removing the extruded cement, and the differences between the two measurements were calculated. Then, each specimen was subjected to a pullout test using a universal testing machine. The load required to dislodge the coping was recorded. The data were analyzed using two-way and one-way analysis of variance and independent sample t tests at a significance level of 0.05. Results: The highest retention values were obtained for 20 µm cement thickness in the conventional technique and the practice abutment cementation technique. The amount of excess cement was the highest for the 50 µm cement thickness obtained for both cementation techniques, whereas the lowest mean values were recorded for the 20 µm cement thickness. Conclusion: The conventional cementation technique is recommended over the practice abutment technique to increase the retention of crowns cemented with provisional cement. However, care must be taken to remove the extruded cement. A cement thickness of 20 µm is preferable for enhancing the retention of cemented crowns and for reducing the amount of excess cement when applying both conventional and practical abutment cementation approaches.

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BACKGROUND: The aim was to assess the peri-implant clinicoradiographic status and prostaglandin E2 (PGE2) levels in peri-implant sulcular fluid (PISF) samples collected from individuals with cement-retained and crew-retained implants. METHODS: In this observational study, participants with cement-retained and screw-retained implants were enrolled. A questionnaire was utilized to gather demographic information and assess the educational background of the participants. Peri-implant modified plaque and bleeding indices, probing depth, and crestal bone loss were measured. Subsequently, PISF samples were collected, and corresponding volumes were recorded. Commercial kits employing enzyme-linked immunosorbent assay were employed to quantify PGE2 levels. The sample size was determined, and group comparisons were conducted using the Student t test and the Mann-Whitney U-test. Logistic regression models were constructed to evaluate the correlation between PGE2 levels and clinicoradiographic and demographics. The predefined level of significance was established at P < .05. RESULTS: Sixty-seven participants, consisting of 33 with cement-retained implants and 34 with screw-retained implants, were included in the study. The mean ages for individuals with cement and screw-retained implants were 54.2 ± 8.7 and 58.7 ± 7.4 years, respectively. The majority of participants had completed university-level education. Reportedly, 87.9% and 82.4% of individuals with cement and screw-retained implants, respectively brushed teeth twice daily. No significant differences were observed in clinicoradiographic parameters, PGE2 volume, and levels between cement-retained and screw-retained implants. There was no correlation between PGE2 levels and peri-implant clinicoradiographic parameters among individuals with either cement-retained or screw-retained implants. CONCLUSIONS: Cement-retained and screw-retained implants exhibit a consistent peri-implant clinicoradiographic status, accompanied by stable levels of PGE2 in PISF provided oral hygiene maintenance regimens are stringently followed.

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Aim: Single-tooth implant restorations, whether screw-retained or cement-retained, are essential for prosthodontic rehabilitation despite having low design flexibility, cosmetic appeal, and high 5-year survival rates. Materials and Methods: A study involving 14 patients with missing mandibular first molars used 28 implants and cement-retained and screw-retained prostheses. Patients had a single edentulous gap, adequate dental hygiene, and sufficient bone volume at the implant site. The study adhered to the Helsinki Declaration, followed WHO 2007 safety guidelines, and evaluated soft tissue, bone height, and bone loss. Data analysis included the Student's t-test and Mann-Whitney U-test. Results: In patients between the ages of 17 and 46, single-implant restorations were compared with cement- and screw-retained at 6 months. Abutment screw loosening and peri-implant soft-tissue traits did not differ significantly from one another. Conclusion: The study compared screw- and cement-retained implant restorations in 28 single-tooth implant-supported prostheses over a 6-month functional loading period, finding no significant improvement in either approach.

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BACKGROUND: The screw-retrievable cement-retained (SRCR) design combines the benefits of both screwand cement-retained implant-supported restorations. This concept has sparked interest in implant dentistry. However, there is a lack of research on fracture behaviors and clinical performance of such restorations. OBJECTIVES: The aim of the present article was to review the current literature on the fracture loads and fracture modes of SRCR implant restorations - in vitro studies, and also studies demonstrating the clinical performance of such design. MATERIAL AND METHODS: A literature search was conducted from January 2000 to June 2022, using 6 databases to identify studies on fracture load and clinical performance that fulfilled the eligibility criteria. Thirty-eight studies met the inclusion criteria (22 in vitro and16 in vivo). The in vivo studies comprised case reports/series/letters (9), clinical techniques (2), retrospective/prospective studies (3), and randomized controlled trials (RCTs) (2). RESULTS: The reviewed articles reported the effects of the SRCR design on the fracture risk if screw access channels were filled or unfilled, with regard to their diameter, and the preparation before or after glazing. The effect of the type of material used in the construction on the fracture modes SRCR restorations was also reported. The long-term clinical data was mainly retrospective and referred to metal-ceramic constructions. Limited long-term clinical data was available for all-ceramic materials and high-performance polymers (HPPs). CONCLUSIONS: Screw-retrievable cement-retained implant restorations appear to have potential in the monolithic design. If the SRCR construction is metal-ceramic or made of a veneered material, special design and abutment selection should be considered. High-performance polymers may be recommended as a substitute for posterior implant restoration.

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ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Reis INRD, Fukuoka GL, Nagay BE, Pannuti CM, Spin-Neto R, Silva EVFD. Incidence of peri-implant disease associated with cement- and screw-retained implant-supported prostheses: A systematic review and meta-analysis. J Prosthet Dent. 2023 Oct 2:S0022-3913(23)00563-2. doi:10.1016/j.prosdent.2023.08.030. Epub ahead of print. PMID: 37793953. SOURCE OF FUNDING: None declared. TYPE OF STUDY/DESIGN: Systematic review and meta-analysis.

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PURPOSE: To investigate the distribution of marginal excess cement in vented and non-vented crowns and evaluate the effect of clinical cleaning procedures on the reduction of excess cement. MATERIALS AND METHODS: Forty models with implant analogs in the position of the right maxillary first molar were divided into four groups (n = 10/group, vented/non-vented crowns with or without cleaning procedures). The abutment finish lines were placed 1 mm below the artificial gingiva buccally, mesially, and distally and at the gingival level palatally. A standardized amount (20 mg) of resin cement was applied in a thin layer to the intaglio surface of zirconia vented and non-vented crowns. The excess cement was removed by a dental explorer in groups with cleaning procedures. The distribution (area and depth) of the marginal excess cement was measured at each quadrant (buccal, mesial, palatal, and distal) for all study samples. The data were analyzed using descriptive and analytical statistics (ɑ = 0.05). RESULTS: The area and depth values of the excess cement in each quadrant in the vented group were significantly smaller than that in the non-vented group, both with and without cleaning (p < 0.001). Cleaning procedures significantly reduced the area of excess cement in both vented and non-vented groups (all, p < 0.001 except for p < 0.05 at the buccal aspect of the vented group). The depth of excess cement in the vented group was significantly decreased with cleaning in the buccal quadrant compared with that without cleaning (p < 0.01). However, the depth of excess cement of the non-vented group was significantly increased with cleaning in all quadrants compared with that without cleaning (all, p < 0.001 except for p < 0.05 at the distal aspect). CONCLUSIONS: Crown venting significantly reduced the area and depth of the marginal excess cement in vitro. Cleaning procedure with a dental explorer significantly reduced the area of marginal excess cement in vitro; however, the excess cement can be pushed deeper in the non-vented group.

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PURPOSE: To evaluate the survival of and incidence of mechanical complications with single- and multiple-unit cement-retained posterior implant-supported restorations with custom CAD/CAM Atlantis titanium abutments (Dentsply Sirona, Charlotte, NC, USA). MATERIALS AND METHODS: This retrospective clinical study analysed 196 Astra Tech OsseoSpeed TX Internal Hexagon implants (Dentsply Sirona) placed in 85 patients between January 2011 and January 2021. Customised Atlantis titanium abutments and cement-retained metal-ceramic crowns were employed. The clinical outcomes recorded were implant and abutment survival rates, and mechanical complications. The results were analysed according to implant length and diameter, arch, implant position and single- or multiple-unit restoration. RESULTS: Over the observation period (up to 10 years), implant and abutment survival rates were 98.5% and 100.0%, respectively. The mean observation period for the single- and multiple-unit implant-supported restorations was 106.00 ± 20.84 months, with a minimum of 41 months and a maximum of 120 months. For the 67 single-unit and 129 multiple-unit posterior implant-supported restorations, four mechanical complications were recorded: two cases of screw loosening, one case of chipping or fracture of veneering materials, and one case of crown decementation. No screw or abutment fractures were observed. CONCLUSIONS: According to the results of this retrospective clinical study, cement-retained posterior implant-supported restorations with custom CAD/CAM Atlantis titanium abutments showed high survival rates over a follow-up period of up to 10 years. No statistically significant differences were recorded when comparing implant position, implant diameter, implant length, single- versus multiple-unit restoration and arch.

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BACKGROUND: Straight preparable abutments and titanium bases (ti-base) can be used to support single-unit screw-retained lithium disilicate implant-supported restorations. The choice between using both abutments depends on many factors. The purpose of this in vitro study was to compare the masking ability, marginal adaptation, and fracture resistance of screw-retained lithium disilicate implant-supported crowns cemented to straight preparable abutments and ti-bases. METHODS: Twenty laboratory implant analogs (Straumann Bone Level; Straumann AG) were randomly divided into 2 groups (n = 10 each) according to the type of the abutment used. Preparable abutment group and ti-base group. Lithium disilicate crowns were used to restore the specimens. All specimens were subjected to thermocycling (from 5 to 55 °C for 2000 cycles) followed by cyclic loading (120 000 cycles). The vertical marginal gap between the abutment finish line and the most apical part of the crown was measured in (µm) by using a stereomicroscope after cementation and after thermocycling and cyclic loading. A spectrophotometer was used to evaluate the masking ability of the specimens after cementation. The load required to fracture the crowns was measured in Newtons (N) by using a universal testing machine after thermocycling and cyclic loading. The Shapiro-Wilk test of normality was used. The appropriate statistical test was used. RESULTS: Regarding the masking ability, the color difference (∆E) showed no statistically significant difference between the ti-base group (2.6 ± 0.2) and the preparable abutment group (2.6 ± 0.3) (P = .888). The average of the microgap values (µm) was greater in ti-basegroup after cementation (13.9 ± 9.2) than preparable group (7.63 ± 1.78) with no statistically significant difference between the 2 groups (P = .49). After cyclic loading and thermocycling, the average microgap values (µm) was significantly greater in the ti base group (21.3 ± 7.4) than in preparable group (13.3 ± 1.5) (P = .02). The load required to fracture the specimens was greater in the preparable group (1671.5 ± 143.8) than in the ti-base group (1550.2 ± 157.5) with no statistically significant difference between the 2 groups (P = .089). CONCLUSION: The abutments used in the present study did not compromise the masking ability of the screw-retained lithium disilicate implant supported crowns. Moreover, the crowns cemented to preparable abutments had better marginal adaptation and higher fracture resistance when compared to those cemented to ti-bases. CLINICAL IMPLICATIONS: Straight preparable abutments are considered as an alternative to the ti-bases when restoring single screw-retained lithium disilicate implant-supported crowns with comparable fracture resistance, marginal adaptation, and masking ability.

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PURPOSE: To assess the fracture resistance of monolithic zirconia crowns cemented with different types of cement on cement-retained implant abutments. MATERIALS AND METHODS: Forty implant analogs were positioned in acrylic resin blocks, and cement-retained straight implant abutments were fastened to the analogs. Crowns were designed with/without occlusal vent holes and produced from monolithic zirconia blocks by the CAD-CAM technique. The two crown types were divided into two groups and cemented with resin and zinc-polycarboxylate cement under 5 kg weight. A universal testing machine applied compressive forces to the crowns until fracture. Fracture resistance values were analyzed using two-way ANOVA and the independent samples t-test with statistical significance set at p < 0.05. RESULTS: According to the two-way ANOVA results, although the crown design did not have a significant effect on fracture resistance (1417.65 ± 337.39 N, 1565.16 ± 517.12 N; crowns with and without vent holes, respectively), the main effect of the cement variable on the fracture resistance was significant. Zinc-polycarboxylate cement (1680.1 ± 375.23 N) showed higher fracture resistance than resin cement (1302.71 ± 420.64 N) in the crowns designed with vent holes (p < 0.005). CONCLUSION: The use of cement-retained implant-supported monolithic zirconia crowns with an occlusal vent hole is safe, and zinc-polycarboxylate cement use may be an appropriate choice for cementation of these crowns.

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La realización de un nuevo tratamiento luego de un fracaso con implantes dentarios representa un gran desafío para el profesional especialistas en implan-tología, así como para el paciente que debe someter-se a un nuevo procedimiento para rehabilitarse. En estos casos, el diagnóstico y la planificación exhaus-tiva previa nos permiten optimizar el tiempo y los re-cursos, arribando al resultado esperado de forma eficiente. En este reporte de caso se presenta la re-habilitación de una paciente que acude a la consulta con un fracaso implantario previo y con alta deman-da estética. Se diseñó una guía quirúrgica de preci-sión para la colocación de un implante Straumann®Bone Level Tapered 3,3 NC ­ Narrow CrossFit® ø 3,3 mm 8 mm junto a la regeneración ósea guiada para compensar la deficiencia de los tejidos circundantes. La rehabilitación protésica consistió en una corona cemento atornillada en disilicato de litio. En el control al año pudo valorarse la estabilidad de la rehabilita-ción protésica, así como de los tejidos circundantes y el contorno estético junto al perfil de emergencia mimético logrado al final del tratamiento (AU)

Carrying out a new treatment after a failure with dental implants represents a great challenge for the implantology specialist professional, as well as for the patient who must undergo a new procedure to rehabilitate. In these cases, the diagnosis and prior exhaustive planning allow us to optimize time and resources, arriving at the expected result efficiently. This case report presents the rehabilitation of a patient who comes to the clinic with a previous implant failure and with high aesthetic demand. A precision surgical guide was designed for the placement of a Straumann® Bone Level Tapered 3.3 NC ­ Narrow CrossFit® ø 3.3 mm 8 mm implant together with guided bone regeneration to compensate for the deficiency of the surrounding tissues. The prosthetic rehabilitation consisted of a screw-retained cement crown in lithium disilicate. In the one-year control, the stability of the prosthetic rehabilitation, as well as the surrounding tissues and the aesthetic contour, together with the mimetic emergence profile achieved at the end of the treatment, could be assessed (AU)

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Background/purpose: The narrow alveolar ridge in the maxillary premolars area limits the angle of implant placement and the shape of the prosthesis. The aim of this study was to evaluate which implant prosthesis, screw-and-cement-retained prosthesis (SCRP) or cement-retained prosthesis (CRP), was more suitable for the maxillary premolar area. Materials and methods: We conducted virtual implantation on 58 implant images from 47 patients obtained using cone beam computed tomography (CBCT). The width and buccal inclination of the alveolar bone, the angulation of the implant fixture, and the angulation of abutment were measured and calculated. Results: We determined that SCRP was feasible in 52% and 78.8% of first and second premolar areas, respectively. There was a positive relationship between the feasibility of SCRP and the premolar region in general (P = 0.031), although SCRP was more likely to be a possibility in the second premolar area. On multiple logistic regression analysis, the difference in the angle between the axis of the prosthesis and the axis of the alveolar bone (RA) was significantly associated with the type of prosthesis (P = 0.001). The RA was significantly higher for CRP implants (OR = 1.885; 95% CI: 1.31 to 2.70). Conclusion: SCRP is not always feasible in the maxillary premolar area, especially in the first premolar area. If the difference between the angle of the axis of the prosthesis and the axis of the alveolar bone is large, it may be necessary for the clinician to consider CRP in the treatment planning stage.

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Background/purpose: Cement-retained restorations have the advantages of passive fit, less complexity of clinical and laboratory methods, cost, esthetics, and dimensional stability over screw-retained restorations, especially in multiple abutment implant-supported prostheses. A common and difficult technical problem with cement-retained implant prostheses is abutment screw loosening. Three-dimensional (3D) printing is a technology that has been rapidly developed and has become widely accepted in dentistry. The aim of this study was to establish a novel method of using 3D implant planning guide to locate the abutment screw in cement-retained implant prosthesis. Materials and methods: Six standard gypsum complete denture models were used to locate the abutment screw. An implant analog (4.5 mm in diameter and 12 mm in length) was placed in the drilling hole (5 mm in diameter and 14 mm in depth). After scanning with a 3D scanner, the 3D printing software was used to design the abutment screw location guide, which was printed by a resin-based 3D printer. Results: A total of 30 abutment screws were located and removed using the guide. The locating guide's actual diameter was 2.4 mm. The drilling point was accurate and precise, and no excessive loss of the abutment was noticed. Conclusion: The guide would help the dentist in locating the abutment screw access channel, resulting in a more precise and accurate drilling point. The guide for locating the abutment screw enhances the accuracy of screw channel access and reduces damage to the crown and abutment.

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OBJECTIVE: To compare 5-year biological, technical, aesthetic, and patient-reported outcomes of single-tooth implant-supported all-ceramic versus metal-ceramic restorations. MATERIALS AND METHODS: Thirty patients with 63 premolar agenesis participated in the 5-year follow-up. The prosthetic treatment on single-tooth implants was randomly assigned to all-ceramic crowns on zirconia abutments (AC = 31) or metal-ceramic crowns on metal abutments (MC = 32). All patients were recalled to clinical examinations at baseline, 1, 3, and 5 years after prosthetic treatments. Biological, technical, and aesthetic outcomes including complications were clinically and radiographically registered. The patient-reported outcomes were recorded using OHIP-49 questionnaire before treatment and at each follow-up examination. RESULTS: At the 5-year examination, the survival rate was 100% for implants and 100% for AC and 97% for MC crowns and abutments. The marginal bone loss after 5 years was minor and not significantly different (p = .056) between AC (mean: 0.3, SD: 1.1) and MC (mean: -0.1, SD: 0.4) restorations. The success rate of the implants based on marginal bone loss was 77.4% for AC- and 93.7% for MC restorations. The marginal adaptation was significantly better for MC than for AC restorations (p = .025). The aesthetic outcomes and patient-reported outcomes between AC and MC restorations were not significantly different. CONCLUSIONS: The biological, aesthetic and patient-reported outcomes for implant-supported AC and MC restorations were successful and with no significant difference after 5-years. The marginal adaptation of the MC crowns cemented on titanium abutments showed a significantly better fit than restorations based on zirconia crowns cemented on zirconia abutments.

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BACKGROUND: This in vitro study aimed to provide evidence regarding the selection of hole diameters of implant crowns to reduce excess cement extrusion at the abutment margin, and to examine the maintenance of their retention capacity in anterior and posterior cement-retained implant crowns. METHODS: Six groups of implant crowns were prepared according to the position of the teeth and the size of their holes as follows: anterior crown without hole (ANH), anterior crown with 1-mm mini venting hole (AMH), anterior crown with 2.5-mm regular screw access hole (ARH), posterior crown without hole (PNH), posterior crown with 1-mm mini venting hole (PMH), and posterior crown with 2.5-mm regular screw access hole (PRH). Temporary cement was used to bond the crowns to the abutments. The mean amount of excess cement extrusion among the different groups at the abutment margin was calculated. Retentive strength under different hole designs was measured as the dislocation force of the crown using a universal testing machine. One-way ANOVA and Welch's t-test were used to analyze the results. RESULTS: The average amounts of extruded excess cement were 18.96 ± 0.64, 1.78 ± 0.41, and 1.30 ± 0.41 mg in the ANH, AMH, and ARH groups, respectively, and 14.87 ± 0.36, 1.51 ± 0.40, and 0.82 ± 0.22 mg in the PNH, PMH, and PRH groups, respectively. The hole opening in the crowns could significantly reduce residual cement regardless of its size (p < 0.001). The mean retentive strengths were 54.16 ± 6.00, 47.63 ± 13.54, and 31.99 ± 7.75 N in the ANH, AMH, and ARH groups, respectively, and 57.84 ± 10.19, 53.22 ± 6.98, and 39.48 ± 5.12 N in the PNH, PMH, and PRH groups, respectively. The retention capacity of the implant crown deteriorated rapidly as the holes on the crown surface enlarged. CONCLUSIONS: The presence of a hole on the implant crown reduced the amount of excess cement. The retention ability of the implant crowns deteriorated as the size of the hole increased. Considering the esthetic effect of the crown and the possible influence on crown retention, an implant crown with a 1-mm mini venting hole is a better clinical choice than the one with a 2.5-mm regular screw access hole.

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OBJECTIVES: This research aimed to compare the oral health-related quality of life (OHRQoL) between fully dentate subjects and edentulous patients wearing implant-supported fixed partial dentures (i-FPDs). The clinical conditions of both types of restorations were evaluated. METHODS: Participants were assigned to: Group-1 (SR, n = 50): screw-retained i-FPD wearers; Group-2 (CR, n = 50): cement-retained i-FPD wearers; and Group-3 (ND, n = 50): dentate subjects with a healthy natural dentition (controls). Patients answered the OHIP-14sp and QoLIP-10 questionnaires. Data related to sociodemographics, prosthesis features, peri­implant status, complications, and subjective evaluations, were compiled. Potential modulators of the OHRQoL and the i-FPDs' clinical conditions were assessed using non-parametric tests (α= 0.05). RESULTS: ND individuals were the least satisfied (OHIP-14sp; p< 0.001). Both prosthodontic groups reported similar levels of wellbeing, excluding the speaking difficulties, which were lower for SR wearers as shown by both scales (p = 0.001). The most discontented patients (OHIP-14sp) were: women (p = 0.022), under 65 years (p = 0.03), without partner (p< 0.001) and having a crown (p = 0.033). The level of education/schooling also affected the OHIP-14sp scores (p< 0.001). Implant mobility and peri­implantitis were more frequent among CR wearers (p-values= 0.008 and 0.05, respectively). CONCLUSIONS: The OHRQoL of both prosthodontic groups was comparably higher than that of the dentate subjects, who were the most nonconformist. The self-perceived satisfaction was mainly modulated by sociodemographic factors. CLINICAL SIGNIFICANCE: Overall, the retention system did not impact the OHRQoL, prosthetic problems, and subjective evaluations of i-FPD wearers. However, the cementation may increase the risk of peri­implant diseases.

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OBJECTIVE: To investigate the effects of implant-supported zirconia crowns with various vent designs on the marginal excess cement (MEC) and retention values under different cement application patterns. MATERIALS AND METHODS: Cercon zirconia crowns (n = 36) were divided into the following groups: no venting (NV group), a small occlusal vent hole (SOV group), a large occlusal vent hole (LOV group), and a small palatal-occlusal vent hole (SPV group). The cement was applied to the crowns with different methods: occlusally half axial walls (OH), cervically half axial walls (CH) and all axial walls (AA), and different amounts of cement were applied with a chosen method. The weight of the MEC was calculated, and the retention force was recorded. ANOVA was used to analyze the MEC weights and retention values. RESULTS: In all vented groups, the OH application method resulted in no MEC and the least retention force, and the AA method expressed significantly less MEC (p < 0.01) than the CH method without retention force reduction. At each amount of cement (5, 10, 20, 30 mg), all three venting designs significantly reduced the MEC by the AA method, and the mean MEC of the LOV group was lower than that of any other group. CONCLUSIONS: Applying a thin layer of cement evenly to all axial walls of vented zirconia crowns showed excellent clinical effects regarding the MEC and the retention force. CLINICAL SIGNIFICANCE: Residual excess cement was identified as a possible risk indicator for peri-implant diseases. Simply and effectively minimizing marginal extrusions without reducing the retention force has clinical value. The results of this study indicate that applying a thin layer of cement evenly to all axial walls of vented zirconia crowns is an acceptable method.

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PURPOSE: This is a clinical study to compare complete digital workflows generated using intraoral scanning and the split-file technique with a conventional workflow for cement-retained implant-supported restorations. MATERIALS AND METHODS: Forty patients requiring posterior single-unit implant restorations were included. Twenty patients were randomly assigned to the complete digital workflow group, involving intraoral scanning and manufacture of cement-retained crowns using the split-file technique (test group). The remaining 20 patients were assigned to the hybrid workflow group (control group), involving conventional impressions and CAD-CAM fabricated crowns based on stone casts. Scanning of the crowns was performed before and after clinical adjustment using an intraoral scanner (TRIOS Color; 3Shape). Two 3D digital models were trimmed and superimposed to evaluate changes in dimensions using Geomagic Control 2014 software. Chair-side and laboratory times for the entire workflow were recorded. Independent-sample t tests were used for the statistical analysis. RESULTS: All crowns were inserted without refabrication. The average maximum occlusal adjustment of the crowns, measured as maximum deviation of occlusal area in superimposed pre and post scans, was -212.7 ± 150.5 and -330.7 ± 192.5 µm in the test and control groups, respectively (p = 0.037). The average area of occlusal adjustment, measured as area of deviation larger than 100 µm, was 8.4 ± 8.1 and 17.1 ± 12.3 mm2 in the test and control groups, respectively (p = 0.012). The mesial and distal contact adjustment amounts, maximum deviations of proximal area, were -33.0 ± 96.2 and -48.6 ± 70.5 µm in the test group, and -3.7 ± 66.7 µm and -11.4 ± 106.7 µm in the control group, respectively. The mean chair-side time was 20.20 ± 3.00 and 26.65 ± 4.53 minutes in the test and control groups, respectively (p < 0.001). The mean laboratory time was 43.70 ± 5.56 and 84.55 ± 5.81 minutes in the test and control groups, respectively (p < 0.001). CONCLUSIONS: Single-unit cement-retained crowns with complete digital workflows required fewer crown adjustments and had shorter clinical and laboratory times compared to conventional impressions and hybrid workflows. Digital impressions and the split-file technique provided customized abutments and cement-retained crowns, thus broadening the indications for digital workflows for implants.

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PURPOSE: The aim of the present 10-year follow-up study was to assess the survival rate of cement- and screw-retained restorations on dental implants placed in grafted sites. MATERIALS AND METHODS: Patients with cement- (group 1) and screw-retained (group 2) restorations on implants placed in grafted sites and patients with cement- (group 3) and screw-retained (group 4) restorations on implants placed in non-grafted sites were included. Demographic data was recorded using a questionnaire, and information regarding implant dimensions, surface characteristics, insertion torque, type of bone graft used, jaw location and duration of implants in function was retrieved from patients' records. These patients were evaluated for peri-implant crestal bone loss (CBL), probing depth (PD), modified plaque index (mPI), and modified bleeding on probing (mBOP). p < 0.05 was considered statistically significant. RESULTS: Eighty-eight partially edentulous individuals (n = 22 in each group) were included. The mean ages of individuals in all groups were comparable in all groups. In each patient, 1 bone-level platform-switched dental implant with moderately rough surfaces was placed using an insertion torque of 30-35 Ncm. In all groups, the length and diameter of implants ranged between 11-14 mm and 4.1-5 mm, respectively. There was no statistically significant difference in mPI, mBoP, PD, and mesial and distal CBR around implants in any of the groups. CONCLUSION: Bone-level implants restored with cement and screw-retained restorations can possess a stable clinicoradiographic status and remain functional in grafted and non-grafted sites, provided strict domestic oral hygiene measures are adopted and routine dental prophylaxis is carried out by oral healthcare providers.

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RESUMEN: Introducción: Los implantes dentales se han transformado en una opción de tratamiento de suma relevancia para pacientes parcial o totalmente desdentados. El éxito del tratamiento puede verse afectado por la elección del tipo de retención de estos (cementada o atornillada). A pesar que ambas presentan ventajas, aún no existe consenso sobre el mejor tipo de retención para restauraciones fijas implantosoportadas. Métodos: Realizamos una búsqueda en Epistemonikos, la mayor base de datos de revisiones sistemáticas en salud, la cual es mantenida mediante el cribado de múltiples fuentes de información, incluyendo MEDLINE, EMBASE, Cochrane, entre otras. Extrajimos los datos desde las revisiones identificadas, analizamos los datos de los estudios primarios, realizamos un metanálisis y preparamos una tabla de resumen de los resultados utilizando el método GRADE. Resultados y conclusiones: Identificamos 14 revisiones sistemáticas que en conjunto incluyeron 43 estudios primarios, de los cuales cinco corresponden a ensayos aleatorizados. De estos, solamente dos ensayos responden a la pregunta de interés de manera directa. Concluimos que las coronas atornilladas podrían aumentar levemente el riesgo de pérdida de implante a largo plazo, podrían resultar en nula o poca diferencia en el riesgo de pérdida de implante a mediano plazo, reabsorción ósea y periimplantitis, pero la certeza de evidencia ha sido evaluada como baja. Por otro lado, no es posible establecer con claridad si las coronas cementadas disminuyen el riesgo de complicaciones estéticas y protésicas, ya que la certeza de la evidencia existente ha sido evaluada como muy baja.

ABSTRACT: Introduction: Dental implants have become a highly relevant treatment option for partially or totally edentulous patients. Implant retention systems (cemented or screwed) can influence the treatment success. Although both have advantages, there is still no consensus on the best type of retention for implant-supported fixed restorations. Methods: We searched in Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach. Results and conclusions: We identified 14 systematic reviews including 43 primary studies overall, of which five were randomized trials. Of these, only two trials answer the question of interest. We concluded that screw-retained crowns may increase long-term implant loss, may make little or no difference in the risk of medium-term implant loss, bone resorption, and peri-implantitis, but the certainty of the evidence has been assessed as low. On the other hand, it is not possible to clearly establish whether cemented crowns reduce the risk of cosmetic and prosthetic complications, since the certainty of the evidence has been assessed as very low.

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AIM: The study aimed to evaluate and compare the effect of incorporating one circumferential groove and bur modification on retention of cast copings on implant abutment cemented with glass ionomer cement. MATERIALS AND METHODS: Fifteen straight shoulder implant abutments casted of height 6 mm used with corresponding 12 mm long stainless steel implant analog. The abutments were divided into three groups of five abutments in each group. Group I: Control group, without any surface modification, Group II: Milling of a circumferential groove, and Group III: Bur modification by creating punches of size whole round bur diameter 5 per axial surfaces. Glass ionomer definitive cement was used to adhere the cast copings to each group of abutments. After thermocycling, the specimens were evaluated for retention using the Instron Universal Testing Machine's pull-out test. The data were analyzed using One-way ANOVA, followed by the Tukey post-hoc test to compare the load among the three groups. RESULTS: According to the findings, the inclusion of a circumferential groove (Group II) increased the retention of glass ionomer cement maintained implant-supported crowns by 44.58%. The bur modification (Group III) boosted glass ionomer cement maintained implant-supported crown retention by 110.69% while retaining retrievability. Results were statistically significant. CONCLUSION: Bur modification revealed more retention when compared to the groove and control group. CLINICAL SIGNIFICANCE: Short abutments are used in the clinical situation where interarch space is less. To achieve adequate retention of the implant crowns, surface modification of the abutments is necessary while selecting a cement-retained prosthesis.

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