The International Journal of Prosthodontics, 3/2022
DOI: 10.11607/ijp.7545Pages 259-268, Language: English
Purpose: To evaluate the success of monolithic endocrowns fabricated using a digital workflow.
Materials and Methods: Twenty-three patients requiring restoration of devitalized molars or premolars were included in the study. The preparation was scanned using an intraoral scanner (Cerec Bluecam, Dentsply Sirona), and a monolithic restoration was made from a nanoparticle resin-based hybrid composite (#10 Cerasmart [CS]; #10 Lava Ultimate [LU], 3M Espe) or a polymer-infiltrated ceramic (#10 Vita Enamic [VE]). At the time of placement and after 6 months, 1 year, and 5 years of function, radiographs were taken to evaluate the marginal integrity of the restorations, and clinical pictures were taken to assess the quality of the restoration using the USPHS criteria.
Results: After 5 years, the restorative success rate was 70.8%, the restorative survival rate was 87.5%, and the tooth survival was 91.6%. Four chippings (two LU, two CS), three fractures (three LU), and two debonding of the restorations (two CS) occurred. Also, two teeth were extracted after 5 years of followup (two VE) because of secondary caries and a root fracture. The USPHS ratings were high, except for color match, which was rated the lowest at all time intervals.
Conclusion: Nanoceramic endocrowns made using a completely digital workflow have an acceptable survival rate after 5 years. However, the complication rate was high.
The International Journal of Oral & Maxillofacial Implants, 3/2022
DOI: 10.11607/jomi.9432Pages 479-484, Language: English
Purpose: The increasing popularity of desktop 3D printers makes guided surgery more accessible. The aim of this in vitro study was to evaluate the accuracy of single-tooth guided implant surgery by means of a 3D-printed tooth-supported guide.
Materials and methods: Fifteen implants were virtually planned to replace a missing first mandibular molar, using planning software for guided implant surgery (Exoplan, Exocad). A tooth-supported guide was designed and manufactured using a desktop 3D printer (Asiga MAX UV). The implants were placed fully guided in resin casts, and a digital impression was taken to register their position. This scan was compared with the virtual implant position in the planning software, and the internal fit of the guides was evaluated using metrology software. One planning was executed six times for measuring precision.
Results: For trueness, the mean angular deviation was 2.63 degrees (SD: 1.69 degrees; range: 0.38 to 5.99 degrees), the mean coronal deviation was 0.52 mm (SD: 0.25; range: 0.09 mm to 1.07 mm), and the mean apical deviation was 0.90 mm (SD: 0.47; range: 0.14 to 1.74 mm). The absolute apical mean deviation in the buccolingual direction (x-axis) was 0.70 mm (SD: 0.42, 0.12 to 1.65 mm; P < .001); in the mesiodistal direction (y-axis), it was 0.34 mm (SD: 0.26; range: 0.01 to 0.80 mm; P = .650); and in the vertical direction (z-axis), it was 0.32 mm (SD: 0.27; range: 0.02 to 1.00 mm; P = .010). The mean internal fit of the guides was 79.5 μm (SD: 19.6 μm; range: 51 to 118 μm).
Conclusion: Desktop 3D-printed tooth-supported guides demonstrate an acceptable fit and acceptable level of accuracy for single implant placement.
Keywords: 3D printing, 3D-printed surgical guide, accuracy, dental implants, edentulous mandibular, guided surgery, intraoral scan, single implant
International Journal of Periodontics & Restorative Dentistry, 1/2018
DOI: 10.11607/prd.3433, PubMed ID (PMID): 29240200Pages 16-23, Language: English
Immediate implant placement is performed less frequently in molar extraction sockets than in single root sockets. This is mainly due to the tripodal anatomical configuration of molar roots, which is perceived as complex and therefore unsuitable. The mechanical burden of molar sites, combined with much larger socket dimensions, make it amenable to the use of ultrawide-diameter dental implants. This article describes a practical, sequenced technique that can be used predictably for immediate implant placement in maxillary and mandibular first molar sockets, using a dry skull model for clarification. This detailed description is based on the experience of more than 580 clinical cases over a 10-year period.
International Journal of Periodontics & Restorative Dentistry, 5/2015
DOI: 10.11607/prd.2494, PubMed ID (PMID): 26357701Pages 714-723, Language: English
This study evaluated the clinical outcomes of immediately loaded maxillary anterior single implants placed in fresh extraction sockets. A patient cohort that was treated 1.5 years earlier was recalled, and 18 patients (6 men, 12 women) with 21 implants were included. Clinical photographs and periapical radiographs were taken at follow-up and baseline to determine the bone loss and change in esthetics. No marginal bone loss was detected at followup (mean bone level ± standard deviation = 0.32 ± 0.82 mm). Immediate implant placement and loading resulted in predictable clinical and esthetic outcomes, with soft and hard tissue levels remaining stable over time.
International Journal of Periodontics & Restorative Dentistry, 1/2015
DOI: 10.11607/prd.2185, PubMed ID (PMID): 25734714Pages 115-121, Language: English
The aim of this study was to evaluate the accuracy, in terms of trueness and precision, of optical dental scanners. An experimental acrylic resin cast was created and digitized using a microcomputed tomography (microCT) scanner, which served as the reference model. Five polyether impressions were made of the acrylic resin cast to create five stone casts. Each dental digitizer (Imetric, Lava ST, Smart Optics, KaVo Everest) made five scans of the acrylic resin cast and one scan of every stone cast. The scans were superimposed and compared using metrology software. Deviations were calculated between the datasets obtained from the dental digitizers and the microCT scanner (= trueness) and between datasets from the same dental digitizer (= precision). With exception of the Smart Optics scanner, there were no significant differences in trueness for the acrylic resin cast. For the stone casts, however, the Lava ST performed better than Imetric, which did better than the KaVo scanner. The Smart Optics scanner demonstrated the highest deviation. All digitizers demonstrated a significantly higher trueness for the acrylic resin cast compared to the plaster cast, except the Lava ST. The Lava ST was significantly more precise compared to the other scanners. Imetric and Smart Optics also demonstrated a higher level of precision compared to the KaVo scanner. All digitizers demonstrated some degree of error. Stone cast copies are less accurate because of difficulties with scanning the rougher surface or dimensional deformations caused during the production process. For complex, large-span reconstructions, a highly accurate scanner should be selected.
International Journal of Periodontics & Restorative Dentistry, 2/2014
DOI: 10.11607/prd.1938, PubMed ID (PMID): 24600655Pages 188-197, Language: English
This prospective study evaluated clinical results of immediately loaded Biomet 3i implants with different surface topographies. Thirty-three periodontally compromised patients received 163 implants (130 in the maxilla and 33 in the mandible; 132 NanoTite and 31 Osseotite). After a mean loading period of 57 months, the survival rate was 96.3%. Mean crestal bone loss was 1.6 mm. No difference in bone loss was detected between the two surfaces. Only 6% of the implants had peri-implantitis based on total bone loss above 2 mm from the day of surgery in conjunction with probing depths of > 4 mm. (Int J Periodontics Restorative Dent 2014;34:189-197. doi: 10.11607/prd.1938)
The International Journal of Prosthodontics, 5/2013
DOI: 10.11607/ijp.3075, PubMed ID (PMID): 23998144Pages 458-464, Language: English
Purpose: The aim of this study was to evaluate and compare the outcomes of immediately loaded all-ceramic crown restorations supported by implants placed in both mature bone and immediate extraction sockets.
Materials and Methods: Forty-three tapered, external hex implants were placed immediately after extraction or in healed bone in a convenience sample of 38 patients from two clinics, with 23 implants immediately placed after tooth extraction and 20 placed in mature bone. Thirty implants were located in the maxilla and 13 in the mandible. Each surgical implant placement was followed by the fabrication of a screw-retained all-ceramic crown (zirconia-toughened alumina cylinder and layered with porcelain) that was then put into immediate function. Each patient was recalled annually for clinical and radiographic assessments.
Results: All implants were loaded immediately and all functioned successfully following a mean follow-up of 26 months. Significantly more bone loss was recorded around delayed implants compared with immediately placed ones. Smoking, platform switching, and jaw location did not influence peri-implant bone loss. Porcelain chipping was noted in the case of two crowns.
Conclusion: The short-term outcome of prefabricated ceramic cylinders used to support a single screw-retained crown was regarded as successful. Immediate implant placement did not appear to increase the risk for implant failure and was accompanied by reduced peri-implant bone loss.
The International Journal of Oral & Maxillofacial Implants, 4/2013
Online OnlyDOI: 10.11607/jomi.3052, PubMed ID (PMID): 23869374Pages 1026, Language: English
Purpose: Marginal bone loss around implants is of great concern, and its cause may be multifactorial. Recently, clinical cases presenting marginal bone loss, in most cases accompanied by vertical fracture of internal-connection implants in the buccolingual direction, have been reported, in which unfavorable stress distribution is one possible cause of marginal bone resorption. The purpose of the current study was to characterize this type of marginal bone loss and implant fracture by conducting a finite element analysis (FEA).
Materials and Methods: Clinical and radiographic evaluations showed that the prostheses of all reported cases had implant-level setups and were directly screwed to the internal implants. Intriguingly, all vertical fractures reported were in the buccolingual direction. Therefore, to characterize the specific implant fractures, FEA was conducted with misfit models created for two different setups, abutment-level and implant-level, both with screw-retained prostheses. The models were subjected to initial misfits of 0 µm (representing perfect fit), 50 µm, 100 µm, 150 µm, or 200 µm, and vertical loading was then applied.
Results: FEA revealed that, for the implant-level setup, excessive stress at the neck of the implant gradually increased in the buccolingual direction as the misfit increased. This result was not seen for the abutment-level setup. A broad maximum stress distribution was evident for the implant-level setup but not for the abutment-level setup.
Conclusion: Broad distribution of excessive stress in the FEA correlated to the clinical cases, and marginal bone loss in these cases may be associated with mechanical alterations. To avoid unnecessary complications, selection of an abutment-level setup is strongly suggested.
Keywords: finite element analysis, implant vertical fracture, marginal bone loss, mechanical alteration, misfit
International Journal of Oral Implantology, 3/2012
PubMed ID (PMID): 23000709Pages 253-262, Language: English
Purpose: To evaluate whether platform switching could preserve marginal bone around implants up to 6 months after loading.
Materials and methods: 15 patients were selected for a randomised controlled trial. Each patient received one customised wide body implant, with the external hex connection located eccentrically, allowing an extra 1 mm switch on one side. The hex was positioned at random at the mesial or distal side and the implant was loaded after 6 months of non-submerged healing. Patients were examined at 3, 6 and 12 months after surgery, during which a radiograph was taken to evaluate bone levels. At 12 months, the mucosal thickness was measured using a perio-probe.
Results: All implants survived and the mean overall bone loss, calculated from both the switched and non-switched side, was 0.39 mm (SD 0.33, range 0.00-1.45), 0.85 mm (SD 0.59, range 0.10-2.50) and 0.80 mm (SD 0.46, 0.26-1.89) after 3, 6 and 12 months, respectively. The bone loss continued up to 6 months but stabilised thereafter (P = 0.615). Significantly more bone loss was observed at the non-switched side compared to the switched side at 3 months (0.51 mm versus 0.28 mm, P = 0.019), 6 months (1.05 mm versus 0.64 mm, P = 0.002) and 12 months (0.94 mm versus 0.66 mm, P = 0.002). The mean mucosal thickness was 4.22 mm (SD 1.45; range 1.50-7.00), and was not significantly different between the switched and non-switched sides (P = 0.882). However, using a post-hoc analysis with the mean thickness as a threshold, the mean bone loss was only significantly different between switched and non-switched sides when the mucosa was thicker than 4.22 mm (P = 0.036).
Conclusions: The outcome of this randomised trial is in accordance with earlier studies suggesting that that platform switching decreases bone loss by 30%. Although the sample size was limited, it seems that the creation of a biologic width affects peri-implant bone loss to a significant extent and that platform switching is only effective when the mucosal thickness allows the establishment of a biologic width.
Keywords: bone loss, implant, platform switching, southern implants, wide body