Interim Restorations Research Articles

Randomized clinical trial of a conventional and a digital workflow for the fabrication of interim crowns: An evaluation of treatment efficiency, fit, and the effect of clinician experience

Statement of problemLimited information is available regarding the fabrication of tooth-supported interim single crowns (SCs) with either a digital or a conventional workflow. PurposeThe purpose of this randomized clinical trial was to compare the time efficiency and fit of interim crowns fabricated by using either a digital or a conventional workflow. Material and methodsForty participants in need of posterior tooth-supported SCs were enrolled and randomly allocated to either the digital or conventional group. In the digital group, the interim SCs were fabricated by using digital sextant scans and computer-aided design and computer-aided manufacturing (CAD-CAM) technology without definitive casts. The conventional group included conventional impressions and direct fabrication of the interim restorations intraorally. Five experienced and 5 less experienced clinicians were randomly assigned to fabricate the interim SCs. The total fabrication time (laboratory and clinical) was recorded for time efficiency. The fit assessment included marginal fit, proximal contact, occlusal contact, and crown morphology. The evaluated parameters were analyzed with the Mann-Whitney U Test (α=.05). ResultsThe digital workflow required significantly less total fabrication time (laboratory and clinical) than the conventional workflow (P<.001). The less-experienced clinicians needed longer clinical time with the conventional workflow than the experienced ones (P=.023). In contrast, the laboratory time and total fabrication time were shorter for less-experienced clinicians using the digital workflow (P=.005 and P=.015). The interim SCs fabricated with the digital workflow had significantly better fit and occlusal contacts than those fabricated with the conventional workflow (P=.005 and P<.001). With the digital workflow, the interim SCs made by less-experienced clinicians were of the same quality as those made by experienced clinicians. When using the conventional workflow, the fit of the experienced clinicians was significantly better than that of the less-experienced clinicians. ConclusionsThe interim SCs fabricated with a digital workflow required a shorter fabrication time and resulted in better fit than those fabricated with a conventional workflow, especially for less-experienced clinicians.

Design and fabrication of a fixed implant-supported interim restoration from a dynamic navigation virtual plan

A technique is described in which an interim implant-supported restoration was designed and fabricated before surgery from a virtual treatment plan created in and executed with dynamic navigation. The virtual treatment plan was imported into a dental computer-aided design and computer-aided manufacturing (CAD-CAM) software program for the design of the interim restoration. Once designed, the interim restoration was fabricated with additive manufacturing. The soft-tissue contours were evaluated after 12 weeks.

The utilization of snap-on provisionals for dental veneers: From an analog to a digital approach.

There are multiple treatment options to enhance a patient's smile, from conservative bleaching procedures to composite resins, porcelain veneers, or full-coverage crowns. Treating patients with porcelain veneers is a commonly used approach in esthetic dentistry. Provisional restorations for veneers can be time-consuming to make and difficult to retain. This article illustrates a technique for fabricating indirect snap-on provisional restorations for veneer cases, describing both analog and digital approaches. The present article presents an alternative provisionalization technique using snap-on restorations for dental veneers. Application of these techniques will allow for ease of cleansability by the patient leading to healthier soft tissues before the final cementation. Delivery of veneers is more predictable with healthy soft tissue, as bleeding and inflammation may affect the bonding process. This technique is an effective provisionalization option in most veneer cases. This approach seems to be well accepted by patients and a good alternative in helping to maintain optimal gingival health with interim restorations before delivery. The use of snap-on provisionals for veneer restorations will allow the clinician to have an efficient technique with better tissue response before cementation. This prevents inflammation and facilitates a controlled delivery process.

Comparison of Marginal Accuracy of Interim Restoration Fabricated from Self-cure Composite and Autopolymerizing Acrylic Resin: An In Vitro Study.

ABSTRACTBackground and Objectives:One of the important steps toward achieving a successful fixed partial denture treatment is the fabrication of interim restorations with good marginal adaptation. Poor marginal adaptation of the interim restorations will allow ingress of fluids and microorganisms between the restorations and may lead to caries and pulpitis. The objective of this study was to evaluate and compare the marginal accuracy of interim restorations made from two polymethyl methacrylate (PMMA) and two bis-acryl materials.Materials and Methods:An in vitro method was used to replicate a clinical procedure in which the interim crown was made using a direct technique. A maxillary first molar typodont tooth was prepared to receive a full cast crown restoration having 1 mm chamfer and a taper of 5°, and then the prepared artificial tooth was cast into a cobalt chromium metal die. Wax patterns were prepared on the metal die using type 2 inlay wax for full metal crowns. The impression of the die along with the wax pattern was made with a putty-type polyvinyl siloxane, and this impression was used as a mold for making interim restorations. Two PMMA and two bis-acryl provisional crown materials were distributed as follows: Group A: Unifast Trad (GC Dental), Group B: DPI self-cure tooth molding material, Group C: Structur 2 QM (VOCO), and Group D: Cool Temp Natural (Coltene/Whaledent). A total of 60 interim restorations from all the four materials were fabricated (15 interim restorations from each material). The marginal discrepancy of the interim restoration was determined by measuring the space between the margin of the interim restoration and the finish line of the metal die at four vertical reference lines previously marked at the midpoint of the metal die finish line at the buccal, palatal, mesial, and distal surfaces of the die. The marginal gaps were visualized at ×45 magnification using a stereomicroscope and interpreted using ProgRes image capture software.Results:The mean marginal discrepancy calculated in PMMA materials was 269 µm for DPI and 205 µm for Unifast Trad, and the mean marginal gap for the bis-acryl material was 171 µm for Cool Temp and 140 µm for Structur 2 QM.Interpretation and Conclusion:Comparison of marginal accuracy showed that bis-acryl provisional crown material showed better marginal accuracy than PMMA provisional crown material. Among the materials tested, Structur 2 QM showed the best marginal accuracy, and the least marginal accuracy was shown by DPI.

Clinical evaluation of glass ionomer with glass hybrid technology versus conventional high viscosity glass ionomer in class I cavities in patients with high caries risk: Randomized controlled trial

Aim: Glass ionomer is a well-known name in caries management and control. Meanwhile, the dark side in its history is being limited as an interim restoration inside patient mouth. The recently introduced glass ionomer with glass hybrid technology could be a new breakthrough in its future. The aim of this study was to evaluate the clinical performance of glass hybrid glass ionomer compared to conventional high-viscosity glass ionomer in class I cavities in patients with high caries risk. Materials and Methods: In a split-mouth design, 31 high caries risk patients with class I cavities received randomly two pairs of restorations, either EQUIA Forte (glass ionomer with glass hybrid technology) or EQUIA Fil (conventional high-viscosity glass ionomer); both materials were applied according to manufacturer’s instructions. Restorations were evaluated at baseline (1 week) and after 1 year by two blinded assessors using Federation Dentaire Internationale criteria for assessment of dental restoration measuring (functional properties and biological properties). Results: Chi-square test was used to compare the difference between glass-ionomer restorative materials at the base line and after 1 year. A value of P ≤ 0.05 was considered statistically significant. There was no statistically significant difference between both materials for all tested outcomes with 100% success rate (score 1 or 2). Conclusion: Glass hybrid glass-ionomer restoration has shown clinical performance similar to conventional high-viscosity glass-ionomer restoration in class I cavities in patients with high caries risk after 1 year of clinical service.

Resin cutback technique for interim implant-supported crowns

This report describes the direct fabrication of interim implant-supported crowns in a single clinical session by applying a preheated composite resin to a clear silicone matrix made by diagnostic waxing. This technique facilitates the fabrication of custom interim restorations with appropriate soft-tissue molding and enables an inexpensive, predictable, functional, and esthetic outcome after implant surgery.

CAD/CAM: Applications for transitional bonding to restore occlusal vertical dimension.

ObjectiveExplore the best technique for achieving stable and comfortable occlusion. This is critical for long‐term oral health and the foundation of durable esthetic, restorative, periodontal, and prosthodontic treatments.Clinical considerationsVarious techniques and therapies have been proposed for establishing, determining, and restoring ideal centric relation (CR) and vertical dimension of occlusion (VDO) in patients who require restorations and/or full‐mouth rehabilitation. An interim prosthesis phase can help establish and stabilize an enhanced esthetics and/or functional outcome for a limited period of time before the definitive dental restorations are placed. Transitional direct composite bonding and its additive nature have provided clinicians and patients with advantages when establishing a physiologic CR and VDO in interim restorations. However, it is time consuming, tedious, and challenging chairside. The author has been using additive CAD/CAM designed and milled restorations for over 10 years to make transitional bonding more efficient, manageable, and predictable.ConclusionTransitional bonded prostheses are significantly important to providing patients with an interim therapy to determine if the proposed esthetic outcome and occlusal scheme will function as expected, or if adjustments are needed prior to the delivery of the definitive long‐term restorations. CR and VDO are essential for establishing a functional and healthy occlusion, ideal restoration proportions and smile design, and treatment planning esthetic and prosthodontic restorations for long‐term durability.Clinical significanceThis article reviews CR, VDO, and the characteristics of a CAD/CAM transitional bonding technique in reversing the signs and symptoms of a compromised dentition and reestablishing an ideal esthetic and functional occlusal outcome. Transitional bonded prostheses are significantly important to providing patients with an interim therapy to determine if the proposed esthetic outcome and occlusal scheme will function as expected, or if adjustments are needed prior to the delivery of the definitive long term restorations.

A technique for registering the peri-implant soft-tissue profile with an interim restoration

A technique for registering the peri-implant soft-tissue profile with an interim restoration

Assessment of Peri-implant Soft Tissue Adaptive Pressure and Time After Provisional Restorations

Using interim restorations to remodel the peri-implant gingiva contour has been a common procedure in esthetic implant treatment. During the interim restoration delivery, the pressure between the restoration and gingiva typically causes ischemia. Adequate restoration should allow the tissue to recover from ischemia over a certain time. To assess the time needed for peri-implant soft tissue recovery, interim restorations were delivered on 25 single implant sites 2 weeks after stage-two surgery, and the gingiva appearance changes after delivery were recorded for 15 minutes using a video camera. Gingiva color changes along the time were measured and analyzed. The color differences between peri-implant mucosa at 10 min and 0 min, as well as between adjacent tooth gingiva, were all within a clinically acceptable range of color difference. The adaptive pressure technique by two-stage contouring exhibited an optimal peri-implant soft tissue profile within 10 minutes of the adaptive time.

Minimally interventive restorative care of teeth with molar incisor hypomineralization and open apex-A 24-month longitudinal study.

To assess the efficacy of treatment using a minimally invasive approach (selective removal of carious tissue, restoration and preventive strategies) in immature permanent molars with MIH. A total of 281 patients, aged 6-8years, with carious lesions (ICDAS 5-6), severe MIH, and incomplete root formation (one tooth/patient) were included. After clinical and radiographic examinations, selective carious tissue removal was performed, and the teeth received interim restoration for 6months and were then restored with composite resin. Clinical and radiographic follow-up was undertaken, 6, 12, 18, and 24months. A protocol of preventive oral care measures was established and repeated at each follow-up, including diet counselling, oral hygiene instruction, dental plaque control, and topical application of fluoride varnish containing CPP-ACP. All clinical procedures and evaluations were done by a single operator. Clinical and radiographic success was observed 24months after treatment in 96.8% of the cases. Failures were due to enamel fracture at restoration margins, resulting in pulpitis and absence of apex closure. Selective removal of carious tissue, interim, and subsequently definitive restoration, combined with home and professional preventive measures, maintained marginal integrity of restorations in immature permanent molars with severe MIH, confirmed by pulp vitality and occurrence of apexogenesis.

Color dimensions of additive manufactured interim restorative dental material

Statement of problemInterim dental restorations can be fabricated by using additive manufacturing (AM) technologies. Although dental restoration contours can be easily and accurately fabricated by using computer-aided design (CAD) procedures, protocols for creating predictable color dimensions of AM interim restorations are lacking. PurposeThe purpose of this in vitro study was to measure and compare color dimensions of different AM and conventional interim restorative materials. Material and methodsDisks (N=420) were fabricated by using either conventionally (CNV group) or additively manufactured (AM group) materials. The CNV group was further divided into the subgroups CNV-1 (Protemp 4; 3M ESPE) and CNV-2 (Anaxdent new outline dentin; Anaxdent). AM subgroups included AM-1 (FreePrint temp; Detax), AM-2 (E-Dent 400; Envisiontec), AM-3 (NextDent C&B; NextDent), AM-4 (NextDent C&B MFH; NextDent), and AM-5 (Med620 VEROGlaze; Stratasys). Color measurements in the CIELab coordinates were made by using a spectrophotometer (VITA EasyShade Advance 4.0; VITA) with a standardized photography gray card as a background under room light conditions (1003 lux). Color difference (ΔE*) values were calculated by using the CIE76 and CIEDE2000 formulas. The data were analyzed by using the Kruskal-Wallis test with nonparametric pairwise comparisons. ResultsOwing to a software error, the spectrophotometer was unable to measure the color of any specimens in the AM-5 subgroup, which was consequently excluded from further analysis. Significant differences (P=.001) between 2 manufacturing groups were found based on the L* variable. All subgroups were significantly different from each other for all 3 variables (P<.001). Pairwise comparisons revealed that all groups were significantly different from each other, except for the AM-1 and AM-2 subgroups, compared with the CNV-1 subgroup for the L* color dimension. The ΔE* values calculated by using the CIE76 formula varied from 6.63 to 23.1 and by using the CIEDE2000 formula from 3.43 to 10.21, suggesting a perceptible and unacceptable color mismatch between the CNV and AM groups. ConclusionsNone of the additively manufactured interim materials tested matched the conventional interim materials in all 3 CIELab color dimensions.

Validating laboratory simulation with resin-based materials for temporary fixed denture prostheses – Results from clinical and laboratory trials

The aim of the current study was to relate an artificial aging protocol for the analysis of dental materials to their clinical performance. 20 fixed interim restorations (crowns and fixed denture prostheses (FDPs)) fabricated from two commercially available resin-based composites (RBCs) and a previous clinical trial served as templates for the fabrication of duplicate restorations. Duplicates were subjected to artificial aging using thermal cycling and mechanical loading. Subsequent to wear analysis, templates and duplicates were loaded to fracture and were examined using thermal gravimetric analysis (TG) and differential scanning calorimetry (DSC). For both RBCs, a relevant uptake of water was identified, which was more pronounced in the duplicates. Tribological analyses indicated relevant signs of wear in both templates and duplicates. While qualitative analyses indicated macroscopically similar wear traces in templates and duplicates, data showed that wear of FDPs was underrated in the laboratory analyses. The results of the current study suggest that chewing simulation allows a proper estimation of aging processes in materials for the fabrication of fixed interim restorations. However, simulation parameters should be continuously improved using data derived from clinical settings to enhance the quality of the simulation protocols.

Interim restoration technique for gingival displacement with a feather-edge preparation design and digital scan

A straightforward and time-efficient technique is presented for recording digital scans in single- and multiple-unit tooth abutments with feather-edge finish lines. The margins of the interim restoration should be precise and sufficiently deep in the sulcus so that the tissues can be properly displaced. Definitive intraoral scans should be made approximately 3 to 4 weeks after the tooth (or teeth) has been prepared to allow healing of the soft tissues. The interim restoration is first removed and then reseated after removing cement residue. First, a scan is made with the interim restoration in place. The abutment tooth or teeth are then erased from the original digital file, the interim restoration is removed again, and a new scan enclosing only the abutment tooth is made.

Digital custom implant impression technique for capturing the acquired emergence profile

A digital method for capturing the acquired emergence profile from contoured implant interim restorations is described. Three separate digital scans were made by using an intraoral scanner and aligned by using a design software program capable of merging and alignment. The Boolean Difference function was then performed by using a free software program to obtain the emergence profile. This technique may be less time-consuming than analog methods and may be more accurate than existing digital methods.

Transferring subgingival contours around implants and the intaglio surface of the pontic to definitive digital casts by using an intraoral scanner: A technique

The accurate transfer of the subgingival contours of implant-supported restorations and pontics is essential for providing the dental technician with the necessary information to fabricate an optimal definitive fixed dental prosthesis. However, once the interim restoration is removed to make an impression, the subgingival tissue, which is no longer physically supported, tends to collapse. This digital intraoral and extraoral scanning technique offers a way to transfer the subgingival contours and intaglio surface of the interim restoration to the definitive restoration. In addition, this technique can reduce clinical and laboratory time, as well as the necessity of storing gypsum casts.

Combination of cone beam computed tomography and CAD-CAM techniques for maintaining natural emergence profile in immediate extraction and/or implant placement and restoration of a central incisor: A dental technique

For immediate extraction and implant placement, preservation of the natural emergence profile is essential to optimize esthetics. In the technique presented, the Digital Imaging and Communications in Medicine (DICOM) and standard tessellation language (STL) data were merged to simulate the tooth before surgery and to design the interim restoration. The existing tooth and gingival architecture were replicated.

Dynamic changes of peri-implant soft tissue after interim restoration removal during a digital intraoral scan

Statement of problemDuring a digital intraoral scan for an esthetic implant restoration, the peri-implant soft tissue will collapse rapidly after the interim restoration (IR) is removed, making it difficult to replicate the established emergence profile. The rate of this collapse is unclear. PurposeThe purpose of this clinical study was to determine whether significant dimension differences could be found between peri-implant soft tissue supported by an IR and that immediately after removal of the restoration and to assess the changes over time. Material and methodsOptical scans were made of 12 single implant sites in the esthetic zone of 10 participants. The scans in the first group replicated the peri-implant soft tissue contour with the support of the IR; in the second group, scans were made at different times from 0 seconds to 20 minutes after removal of the restoration. The changes in the soft tissue contour, including the height of the mesial papilla, distal papilla, and gingival margin, the facial and palatal soft tissue thickness, and emergence profile discrepancies (EPDs), were assessed. A linear mixed model was built to estimate the EPD. ResultsAfter the removal of IR, the palatal soft tissue thickness increased over time, and only minimal changes were found in the height of the mesial papilla, distal papilla, and gingival margin (up to −0.27 mm at 20 minutes). A significant EPD was immediately present at all the measurement sites after the removal of the IR. The linear mixed model showed a significant positive correlation between the natural logarithm of time and EPD. Significant positive correlations between gingiva thickness/implant depth and EPD were only seen at some of the sites. ConclusionsA small reduction in the papilla level occurred, but no clinical influence on the proximal contact design of the restoration was detected. For the emergence profile, a significant but small discrepancy occurred immediately and continued to increase over time.

CAD-CAM–fabricated interim fixed complete-arch implant-supported restorations based on the existing dentition

An interim restoration is often used to assess the patient's functional and esthetic needs for implant-supported complete-arch fixed prostheses. A digital protocol for accurately transferring information from the existing dentition to the interim restoration is required. The purpose of this clinical report was to describe a digital workflow to fabricate an interim fixed restoration by using the vertical dimension of occlusion and occlusal relationship from the original dentition to provide an accurate, efficient, and predictable computer-aided design and computer-aided manufacturing (CAD-CAM) interim complete-arch implant-supported restoration.

Adhesive residue on the CAD-CAM surgical guide sleeve: A technical report

Computer-aided design and computer-aided manufacturing (CAD-CAM) surgical guides can be used by the clinician and dental technician to create a definitive cast before surgery, thereby allowing an indirect interim restoration to be fabricated. However, the accurate transfer of the interim restoration from the laboratory to the surgical site requires a precise interface between components. This article reports the prosthetic significance of adhesive residue on the intaglio surface of the CAD-CAM surgical guide sleeve, which can create errors in the implant analog position of the definitive cast. A technique for identifying the presence of residue and its careful removal are also introduced.

Influence of interim cements on the optical properties of interim restorations

Statement of problemEven if the appropriate resin shade is selected for an interim restoration, how the optical characteristics of the interim cement affect the esthetics of the interim restoration is unclear. PurposeThe purpose of this in vitro study was to evaluate the effects of interim cements on the optical properties of interim restorations. Material and methodsTwenty dentin disks (6×1 mm) were obtained from the labial surface of bovine incisors. Disks of acrylic and bis-acrylic resins (n=20) with the same dimensions were prepared and cemented over the dentin using the following cements: Bifix Temp (resin-based; VOCO), ClearTemp LC (resin-based; Ultradent Products, Inc), Provicol (VOCO), TempCem NE (Coltène). The same dentin and resin disks were used for all cements. After cementation, the color difference (ΔE00), translucency parameter (TP), and fluorescence of the dentin/cement/resin combinations were compared with each other and with a control group (C), in which a transparent liquid (polyethylene glycol 400; LabSynth) was applied. Color and translucency were evaluated with a spectrophotometer (CM-2600; Konica Minolta) and fluorescence with a spectrofluorophotometer (RF-5301PC; Shimadzu). ΔE00 and TP data were analyzed using 2-way ANOVA. For fluorescence, 1-way ANOVA was used. The Tukey test was used for multiple comparisons (α=.05). ResultsΔE00 values were significantly influenced by the interim material (P<.001) and the interim cement (P<.001). Bifix Temp showed the lowest significant ΔE00 values (P<.001). The highest ΔE00 values were observed for TempCem NE. No differences were observed between the interim resins with respect to TP (P=.318). The lowest translucency values were measured for TempCem NE, followed by Provicol, ClearTemp LC, Bifix Temp, and the control group (P<.001), with no significant differences among the interim resin-based cements. Among the cements, Bifix Temp and TempCem NE yielded fluorescence similar to that of the natural tooth for both interim resins. A similar result was found for bis-acrylic resin combined with Provicol. ConclusionsCementation with interim resin-based cements resulted in better esthetics. However, the high fluorescence of the ClearTemp LC may reduce the esthetics of interim restorations in environments with predominantly UV light.