Primary dental journal最新文献

Aim: The aim of this study was to digitally measure the dimensional changes in an irreversible hydrocolloid impression material (alginate) resulting from varying storage times under optimal storage conditions.

Materials and methods: A single type V dental stone control cast was used to make 25 alginate impressions using perforated stock trays. The impressions were randomly assigned into five groups of five samples each (n=5 per group) with varying storage times: Group 1, poured at 15 minutes; Group 2, poured at one hour; Group 3, poured at 24 hours (one day); Group 4, poured at 72 hours (three days); Group 5, poured at 168 hours (seven days). All impressions were stored in sealed Ziploc® plastic bags with a wet paper towel (100% relative humidity) at room temperature and stored according to the assigned group storage times. All impressions were poured in type V dental stone according to the manufacturer's instructions. The casts were scanned with a digital 3D desktop scanner and saved as electronic stereolithography (.stl) files. Each .stl file of the scanned casts were superimposed on the .stl file of the control cast using Geomagic® Control X™ software. Three preselected fixed comparison measuring points (CMP) on each cast were compared to the control cast. Point one (CMP1) was on the midfacial surface of central incisor. Point two (CMP2) and point three (CMP3) were on the mesiobuccal proximal marginal ridge areas of third molars. The discrepancies between the files at each point were analysed with colour maps, and quantified (Table 1). The tolerance was set at ±10μm. CMP scores were analysed using one-way analysis of variance (ANOVA) and Kruskal-Wallis (K-W) non-parametric H tests.

Results: Average gap distances across groups ranged from 0.04mm (seven-day group) to 0.06mm (one hour and 24-hour groups). Colour maps indicated increased dimensional change with increased storage time up to one day. After three days, shrinkage up to 139μm was measured. ANOVA results for CMP1 (F[4,20] = 1.65, p = 0.020) and CMP3 (F[4,20] = 0.44, p = -0.78) were not statistically significant. Similarly, K-W results for CMP2 were not significant (χ²= 3.62, p = 0.46).

Conclusions: Under optimal storage conditions, there were no significant dimensional changes in casts poured from alginate up to seven days.

By utilising open-source digital software, clinicians can create an integrative digital workflow composed of various technological systems. This report presents a clinical case that follows a comprehensive digital workflow to improve the smile of a 42-year-old female patient. The patient presented with minor attrition of maxillary anterior teeth and discoloured, asymmetrical composite restorations on central maxillary incisors. Her smile was rehabilitated by restoring her maxillary anterior teeth with lithium disilicate ceramic veneers. A smile design system was used to create a virtual simulation of the patient's desired treatment outcome. Utilising a 3D tooth library generated by the smile design system, extra-oral photographs, and intra-oral scans of the patient's maxillary and mandibular arches, a 3D model of the proposed smile design was created in an advanced 3D sculpting software. The resin casts that were fabricated with a 3D printer were used to fabricate a mockup and sent to the laboratory as reference for the final restoration. The specific shade recipe for the ceramic veneers was obtained using a special polar eye filter and digital shade matching software. There is no doubt that advancements in digital technology are providing clinicians with limitless treatment modalities. From intra-oral scanners and smile design systems to 3D sculpting software and even digital shade matching systems, continuous technological developments are paving the way for the complete digitalisation of dentistry. This case report presents an example of this digital revolution.

The influence of different surface treatments and ageing on the shear bond strength (SBS) of computer-aided design/computer-aided manufacturing (CAD/CAM) materials is still contentious. Therefore, this study evaluated the effect of surface treatments and ageing on the SBS of resin cement to polymer-infiltrated ceramic network (PICN) and zirconia-reinforced lithium silicate (ZLS) CAD/CAM materials. Specimens of PICN (n=10) and ZLS (n=10) were submitted to four surface treatment groups: 1) 5% hydrofluoric acid etching (HF) + silanisation (SI); 2) Air abrasion (AB)+HF+SI; 3) HF + universal adhesive (UA); 4) AB+HF+SI+UA. The treated specimens were bonded with resin cement cylinders and tested in SBS after 24 h and one year of water storage. Data were assessed by "analysis of variance" (ANOVA) and Tukey test (α=0.05) and failure modes were classified. No significant differences were observed among treatments at each evaluation time (p>0.05). SBS decreased after one year of storage, except for PICN treated with HF+UA (p=0.068). Air-abraded groups displayed a lower SBS reduction for ZLS. PICN and ZLS exhibited predominantly adhesive and mixed failures, but at one year, PICN cohesive failures increased. In conclusion, HF+UA is an effective surface treatment for PICN, while the combination AB+HF+SI+UA was more appropriate for ZLS. The water storage for one year reduced the SBS for most groups.

This report describes a digital workflow and two-year follow-up of an immediately loaded implant-retained overdenture using flapless surgery and a computer-aided design/computer-aided manufacturing (CAD/CAM) surgical guide. A prosthetically-driven approach, utilising a three-dimensional (3D) planning software and a CAD/CAM surgical guide, was used to place four implants in the edentulous maxillary arch of a 59-year-old male patient. All four implants were inserted through the surgical guide without raising soft tissue flaps. After placement, the patient was delivered an immediately loaded maxillary overdenture. Surgical implant placement was well tolerated by the patient, who reported no discomfort. Following a four-month period, a new implant-retained maxillary overdenture reinforced by a metal framework was fabricated and delivered to the patient. There were no adverse issues noted with neither the implants nor the maxillary overdenture during the two-year follow up period. The technique using the workflow described in this report may be a predictable and affordable alternative in the restoration of edentulous arches as compared to full-arch fixed restorations.

The COVID-19 pandemic has highlighted the benefits which digital technology offers to all aspects of dental practice and education. This paper provides an overview of how digital technology has enhanced clinical and administrative procedures within dental practice, including computer-aided design/computer-aided manufacture (CAD/CAM), digital radiography, 3D printing, patient records, electronic patient referrals and electronic communications from dental practices. It then considers the development of teledentistry (mHealth) and its benefits in enabling distant consultations with patients, who for one reason or another are unable to visit dental practices easily. It then goes on to consider how and why digital dental distance learning materials were provided to general dental practitioners in England by the Department of Health (DoH) (England) and how they evolved. Finally, this paper considers the use of digital technology in dental education by dental schools.