A combined analog and digital workflow for retrofitting a monolithic ceramic crown to an existing removable partial denture.

A clinical and laboratory workflow for fabricating and retrofitting a monolithic ceramic crown to an existing removable partial denture (RPD) is described. A conventional polyvinyl siloxane impression was made of the prepared tooth with the RPD in place. A stone cast was poured and, after die sectioning, scanned with a tabletop scanner. The ceramic crown was designed and fabricated by using a digital workflow to fit the RPD clasp assembly, providing an adequate undercut for the clasp. The crown was then delivered and the RPD evaluated for adequate fit.

Buccal bone thickness of maxillary anterior teeth: A systematic review and meta-analysis.

AIM: To systematically review buccal bone thickness (BBT) in the anterior maxilla in different teeth, age groups and genders. MATERIALS AND METHODS: PubMed, EMBASE and Cochrane databases were searched up to April 2020. Clinical and radiographic studies reporting on BBT of maxillary anterior teeth, with at least 10 patients, were included. A meta-analysis was performed using random effect models to report differences of BBT. RESULTS: 50 studies were included. Using bone crest (BC) as a reference point, no significant differences were found in BBT between different tooth types, except for 0.16 mm (95%-CI: 0.02-0.30) increased mid-root thickness of premolars compared to canines. Using the CEJ as a reference point, canines presented with a significantly increased thickness of 0.32 mm (95%-CI: 0.11-0.54) coronally compared to laterals. When BC was used as reference, males demonstrated a significantly increased thickness of 0.21 mm (95%-CI: 0.15-0.27) apically, while middle-aged adults showed a 0.06 mm (95%-CI: -0.12, -0.01) statistically significant increase in the coronal level compared to older adults. CONCLUSIONS: Few maxillary anterior teeth have BBT greater than 1 mm. Buccal bone tends to get thicker from a coronal to apical position along the root surface and from an anterior to posterior position in the arch.

Immediate digital implant scanning workflow for posterior single implant-supported crowns: A case series.

This case series presents an innovative technique for fabricating single implant crowns in which a digital scan was recorded immediately after the placement of the dental implant. This technique has been used over several years (January 2015 to April 2018) in 34 patients. The detailed workflow of 2 clinical treatments with successful clinical outcomes and short treatment time is described. The immediate digital implant scan workflow concept reduces treatment time for posterior single implant-supported crowns.

Dimensional stability of double-processed complete denture bases fabricated with compression molding, injection molding, and CAD-CAM subtraction milling.

STATEMENT OF PROBLEM: Studies evaluating the dimensional stability of denture bases fabricated by the double processing method are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the dimensional stability of denture bases fabricated by 3 different techniques: compression molding, injection molding, and computer-aided design and computer-aided manufacturing (CAD-CAM) subtraction milling. MATERIAL AND METHODS: Forty-five mandibular denture bases were fabricated from a master cast by a standardized process. A double processing protocol was used with 3 methods: compression molding (PRESS), injection molding (INJECT), or CAD-CAM (CAD). The bases were compared with the titanium master cast after the first processing. By a digital subtraction process, the dimensional stability of the bases was measured at 22 different locations on the intaglio surface. Denture teeth were then positioned according to a standardized protocol, and the denture was processed a second time and finished. The dimensional discrepancy was reassessed after the second processing and compared with the titanium master cast. RESULTS: In all groups, most of the dimensional changes occurred during the first processing (P<.05), with no statistically significant deformation occurring during the second processing (P>.05). The CAD group presented significantly smaller dimensional changes than PRESS (P<.05) and INJECT (P<.05) groups. No significant difference was found in the dimensional stability in the PRESS and INJECT groups (P>.05). CONCLUSIONS: Denture bases fabricated by a CAD-CAM methodology exhibit fewer dimensional changes than either compression or injection molding. Distortion occurred during the fabrication of the denture base, and a second processing did not significantly affect the dimensional stability of the denture base.

Effect of framework design and firing cycle on the success rate of bilayered zirconia crowns.

OBJECTIVE: This study investigated the effect of framework design and modification of porcelain firing cycle on the occurrence of fractures of metal-ceramic and bilayered zirconia crowns after cyclic loading. METHOD AND MATERIALS: Twenty-four zirconia crowns with two different apicocoronal incisal veneering porcelain lengths (ZS = 2.0 mm and ZL = 4.0 mm) were fabricated. Twenty-four metal-ceramic crowns with the same apicocoronal incisal veneering porcelain lengths (MS = 2.0 mm and ML = 4.0 mm) served as the control. All the specimens (n = 48) were thermally and mechanically cycle-loaded (49 N) for 1,200,000 cycles, and then evaluated for cracks and/or bulk fractures with an optical stereomicroscope (×10). In the second part of the study, the influence of firing cycle modification on the success rate of twenty-four bilayered zirconia crowns was also evaluated. Finally, two specimens from each group (n = 12) were sectioned and analyzed using a scanning electron microscope. Load-to-failure of the specimen that did not present bulk fracture was further assessed using a universal testing machine. Statistical analysis was performed with Fisher exact test and Kruskal-Wallis test. RESULTS: A statistically significant lower occurrence of fractures (P < .05) was found after cyclic loading for bilayered zirconia versus metal-ceramic crowns. Modification of the firing cycle did not significantly influence the outcome after cyclic loading for zirconia bilayered crowns (P > .05). CONCLUSION: Within the limitations of this study, porcelain-firing cycle with an extended cooling time did not appear to influence the occurrence of cracks and fractures of bilayered zirconia crowns.

A meta-analysis of complications during sinus augmentation procedure.

OBJECTIVE: The purpose of this systematic review was to assess the difference in the incidence of intraoperative and postoperative complications between the conventional and alternative surgical techniques, during sinus floor augmentation surgery. DATA SOURCES: Electronic databases were searched for publications related to sinus floor augmentation surgery performed with different techniques (ie, conventional lateral window, piezosurgery, osteotome, trephine) and the incidence of complications. The articles were evaluated by independent reviewers, according to predetermined inclusion/exclusion criteria and processed for meta-analysis, following the PRISMA protocol. Initial search returned 3,940 articles, after inclusion/exclusion criteria, and quality assessment 11 articles were included in the meta-analysis: five randomized clinical trials and six retrospective studies. All the 11 included studies compared the incidence of complications in conventional lateral window sinus augmentation surgery versus alternative techniques, including: osteotome (five articles), piezosurgery (four articles), sonic surgery (one article), and trephine (one article). Meta-analysis of the incidence of intraoperative and postoperative complications during conventional lateral window sinus floor augmentation surgery versus alternative techniques, showed a significantly lower incidence of intraoperative complications for the retrospective studies. However, when data from the clinical trials alone were included in the meta-analysis, a statistically significant difference could not be detected for the incidence of intraoperative and postoperative complications. CONCLUSIONS: The use of alternative techniques for sinus floor augmentation surgery (ie, piezosurgery, sonic surgery, osteotome, and trephine) does not necessarily reduce the incidence of intraoperative and/or postoperative complications compared to the conventional technique.

Buccal bone thickness around single dental implants in the maxillary esthetic zone.

OBJECTIVE: To compare the thickness of buccal bone around single dental implants placed in the anterior maxilla (premolar to premolar) inserted with different placement protocols. DATA SOURCES: An electronic search was conducted using MEDLINE (PubMed), Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE, from January 1980 to July 2015. Mean buccal bone thickness around single dental implants was measured and correlation with implant placement protocols, loading protocols, and augmentation method was assessed. A Q-test was used to access the homogeneity of levels of effect. A univariate meta-regression analysis was used for further investigation of the between-study heterogeneity. Two randomized clinical trials and 12 cohort studies were included for statistical analysis. The difference in buccal bone thickness for implants placed with different implant placement protocols (early vs immediate vs delayed) was not statistically significant (P > .05). Loading protocols (immediate vs delayed) also did not significantly influence the thickness of buccal bone. Descriptive analysis showed different buccal bone thickness for dental implants that received different bone grafting materials at the time of placement. CONCLUSION: Different implant placement and loading protocols may not significantly affect the thickness of the buccal bone around single dental implants in the anterior maxilla. Different bone graft materials at the time of implant placement may have an effect on buccal bone thickness.

Digital versus conventional impressions for fixed prosthodontics: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Limited evidence is available for the marginal and internal fit of fixed dental restorations fabricated with digital impressions compared with those fabricated with conventional impressions. PURPOSE: The purpose of this systematic review was to compare marginal and internal fit of fixed dental restorations fabricated with digital techniques to those fabricated using conventional impression techniques and to determine the effect of different variables on the accuracy of fit. MATERIAL AND METHODS: Medline, Cochrane, and EMBASE databases were electronically searched and enriched by hand searches. Studies evaluating the fit of fixed dental restorations fabricated with digital and conventional impression techniques were identified. Pooled data were statistically analyzed, and factors affecting the accuracy of fit were identified, and their impact on accuracy of fit outcomes were assessed. RESULTS: Dental restorations fabricated with digital impression techniques exhibited similar marginal misfit to those fabricated with conventional impression techniques (P>.05). Both marginal and internal discrepancies were greater for stone die casts, whereas digital dies produced restorations with the smallest discrepancies (P<.05). When a digital impression was used to generate stereolithographic (SLA)/polyurethane dies, misfit values were intermediate. The fabrication technique, the type of restoration, and the impression material had no effect on misfit values (P>.05), whereas die and restoration materials were statistically associated (P<.05). CONCLUSIONS: Although conclusions were based mainly on in vitro studies, the digital impression technique provided better marginal and internal fit of fixed restorations than conventional techniques did.

A comparative study of the incidence of Schneiderian membrane perforations during maxillary sinus augmentation with a sonic oscillating handpiece versus a conventional turbine handpiece.

BACKGROUND: Sonic instruments may reduce perforation rates of the schneiderian membrane during lateral window sinus augmentation procedures. This study compares the incidence of membrane perforations using a sonic handpiece with an oscillating diamond insert versus a turbine handpiece with a conventional rotary diamond stone during lateral window sinus augmentation procedures. MATERIALS AND METHODS: A retrospective chart analysis identified all lateral window sinus augmentation procedures done during a defined period. Among these procedures, those performed with a sonic handpiece and an oscillating diamond insert (experimental) and those performed with a conventional turbine and rotary diamond stone (conventional) were selected for this study. Reported occurrences of sinus membrane perforations during preparation of the osteotomy and elevation of the sinus membrane, as well as postoperative complications, were recorded and compared between treatment groups. RESULTS: Ninety-three consecutive patients were identified for a total of 130 sinus augmentation procedures (51 conventional, 79 experimental). Schneiderian membrane perforations were noted during preparation of the lateral window osteotomy in 27.5% of the sinuses in the conventional group and 12.7% of sinuses in the experimental group. During membrane elevation, perforations were noted in 43.1% of the sinuses in the conventional group and 25.3% of sinuses in the experimental group. Both differences in perforation rates were statistically significant (p < .05). There was no statistically significant difference in postoperative complications. CONCLUSIONS: In this study, the use of a sonic instrument to prepare the lateral window osteotomy during sinus elevation procedures resulted in a reduced perforation rate of the Schneiderian membrane compared with the conventional turbine instrument.

Influence of oscillating and rotary cutting instruments with electric and turbine handpieces on tooth preparation surfaces.

STATEMENT OF THE PROBLEM: Rotary and nonrotary cutting instruments are used to produce specific characteristics on the axial and marginal surfaces of teeth being prepared for fixed restorations. Oscillating instruments have been suggested for tooth preparation, but no comparative surface roughness data are available. PURPOSE: To compare the surface roughness of simulated tooth preparations produced by oscillating instruments versus rotary cutting instruments with turbine and electric handpieces. MATERIAL AND METHODS: Different grit rotary cutting instruments were used to prepare Macor specimens (n=36) with 2 handpieces. The surface roughness obtained with rotary cutting instruments was compared with that produced by oscillating cutting instruments. The instruments used were as follows: coarse, then fine-grit rotary cutting instruments with a turbine (group CFT) or an electric handpiece (group CFE); coarse, then medium-grit rotary cutting instruments with a turbine (group CMT) or an electric handpiece (group CME); coarse-grit rotary cutting instruments with a turbine handpiece and oscillating instruments at a low-power (group CSL) or high-power setting (group CSH). A custom testing apparatus was used to test all instruments. The average roughness was measured for each specimen with a 3-dimensional optical surface profiler and compared with 1-way ANOVA and the Tukey honestly significant difference post hoc test for multiple comparisons (α=.05). RESULTS: Oscillating cutting instruments produced surface roughness values similar to those produced by similar grit rotary cutting instruments with a turbine handpiece. The electric handpiece produced smoother surfaces than the turbine regardless of rotary cutting instrument grit. CONCLUSION: Rotary cutting instruments with electric handpieces produced the smoothest surface, whereas the same instruments used with a turbine and oscillating instruments achieved similar surface roughness.

The incidence of membrane perforation during sinus floor elevation using sonic instruments: a series of 40 cases.

This study reports the incidence of complications and sinus membrane perforations when using sonic instruments to prepare the lateral window osteotomy for maxillary sinus augmentation. The charts of 33 consecutive patients (40 sinuses) were reviewed. Sinus membrane perforations were reported in 7 cases (17.5% of procedures), with 3 perforations occurring during preparation of the osteotomy window (7.5% of procedures). Postoperatively, 2 cases of sinus infection (5%) and 2 cases of flap dehiscence (5%) were recorded. This study demonstrates that elevation of the sinus floor with a combination of hand and sonic instruments is feasible and safe, with a limited incidence of complications.

Bibliometrics study on authorship trends in periodontal literature from 1995 to 2010.

BACKGROUND: Biomedical research has grown considerably in the last few decades, and the authorship characteristics of the dental literature as a whole and of its specialty fields has changed significantly. Unfortunately, the bibliometrics of the periodontal literature have not been thoroughly investigated. The aim of this study is to investigate the bibliometrics of periodontal literature, assessing the geographic origin, study design, and topics investigated in periodontal research published from 1995 to 2010. METHODS: Articles published in periodontal journals during 1995 to 2010 were retrieved through hand search. Inclusion/exclusion criteria were applied. The following variables were extrapolated from each article: number of authors, study design, topic investigated, financial support, and geographic origin. The general linear model assessed the influence of independent variables on number of authors per article, and χ(2) test assessed the statistical difference of the variables over years 1995 to 2010. RESULTS: A total of 2,260 articles were reviewed; 2,076 met the inclusion criteria. The number of authors per article increased (P <0.001) from 4.0 (1995) to 5.1 (2010). The proportion of articles published from North America and Europe decreased (P <0.001) from 84.3% (1995) to 58.6% (2010), whereas for Asia and South America the article proportion increased (P <0.001) from 13.8% (1995) to 40% (2010). Research targeting prevention and treatment of periodontal disease is decreasing (P <0.001) in favor of implant-related research. Governmental research funding is increasing (P <0.001). CONCLUSION: Periodontal research significantly changed during the last 15 years.

Peri-Implant Cystic Lesion With Unusual Cellular Changes: A Case Report.

INTRODUCTION: This report describes the history and management of a cyst developing in anatomic contact with an immediately placed dental implant. CASE PRESENTATION: The lesion presented clinically as a facial swelling of the gingiva adjacent to an osseointegrated and restored maxillary right lateral incisor implant. Radiographs showed a well-circumscribed radiolucency, which was contiguous with the implant surface. After reflection of a mucoperiosteal flap, the lesion was enucleated in toto, and the defect was curetted. The bony defect was grafted, and the lesional tissues were sent for histologic analysis. The results demonstrated the presence of a cyst of unknown origin with some unusual cellular changes in localized areas of the cyst lining resembling ameloblasts. Healing occurred uneventfully, and the patient was monitored for recurrence. At the 2-year follow-up appointment, the patient presented no clinical or radiographic signs of recurrence of the lesion. The etiology of this lesion is unknown. CONCLUSION: This case emphasizes the need for histologic diagnosis of peri-implantitis lesions and suggests a need for expansion of the current classification system for peri-implantitis lesions.

Thermodynamic effects of laser irradiation of implants placed in bone: an in vitro study.

Lasers have been proposed for various applications involving dental implants, including uncovering implants and treating peri-implantitis. However, the effect of laser irradiation on the implant surface temperature is only partially known. The aim of this pilot study was to determine the effect of irradiation with diode, carbon dioxide, and Er:YAG lasers on the surface temperature of dental implants placed in bone, in vitro. For this study, one dental implant was placed in a bovine rib. A trephine bur was used to create a circumferential defect to simulate peri-implantitis, and thermocouples were placed at the coronal and apical aspect of the implant. The implant was irradiated for 60 s using four different lasers independently and change in temperature as well as time to reach a 10 °C increase in temperature were recorded. There was wide variability in results among the lasers and settings. Time for a 10 °C increase ranged from 0.9 to over 60 s for the coronal thermocouple and from 18 to over 60 s for the apical thermocouple. Maximum temperature ranged from 5.9 to 70.9 °C coronally and from 1.4 to 23.4 °C apically. During laser irradiation of dental implants, a surface temperature increase beyond the "critical threshold" of 10 °C can be reached after only 18 s.

Sonosurgery for atraumatic tooth extraction: a clinical report.

The preservation of an intact labial plate during tooth extraction is a critical determinant of whether an immediate implant can be placed and is also an important predictor of the esthetic result. The purpose of this clinical report was to present a method for atraumatic tooth extraction by using an air-driven sonic instrument with specially designed inserts. This surgical technique provides the clinician with an efficient method for atraumatic tooth extraction and preservation of an intact labial plate.

Restoration of immediately loaded implants in a minimal number of appointments: a retrospective study of clinical effectiveness.

PURPOSE: The purpose of this study was to assess the clinical effectiveness of an experimental technique versus the conventional method for the fabrication of implant-supported fixed complete dentures. MATERIALS AND METHODS: Between January 2005 and June 2010, edentulous patients who had received rehabilitation by means of nonsegmented fixed implant-supported complete dentures were identified from the pool of individuals treated at Eastman Institute for Oral Health, University of Rochester. Data collection consisted of a chart review and recording of treatment variables in a customized database. Variables of interest included number of implants per patient, time of implant placement, number of appointments required to complete prosthesis fabrication, type of appointments, manufacturing process used for creation of the framework, and fit of the framework. The number of appointments for conventional and experimental protocols was evaluated for statistical significance using two-way analysis of variance. Presence or absence of clinically acceptable prosthesis fit with the two techniques was evaluated using the Fisher exact test and exact logistic regression analysis. RESULTS: Forty-two patients (48 arches) were included. When the experimental technique was used, prosthesis fabrication and delivery required an average of 4 appointments, whereas the conventional technique required an average of 7.8 appointments to deliver the definitive prosthesis. The prostheses fabricated with the experimental technique showed clinically passive fit on the implants in 17 of 18 arches. The frameworks fabricated with the conventional technique achieved clinically passive fit in 18 of 30 arches. CONCLUSIONS: The experimental technique significantly reduced the number of appointments required to fabricate a nonsegmented fixed implant-supported prosthesis. Moreover, this experimental technique provided clinically acceptable fit of the prosthesis in a significantly greater number of cases compared to a conventional implant elastomeric impression technique.

Clinical evaluation of immediate loading of electroeroded screw-retained titanium fixed prostheses supported by tilted implant: a multicenter retrospective study.

STATEMENT OF PROBLEM: Immediate occlusal loading of dental implants in the edentulous mandible has proven to be an effective, reliable, and predictable treatment protocol. However, there is limited long-term data available in the literature, when an electroeroded definitive cast-titanium fixed prosthesis is used for this treatment protocol. PURPOSE: The aim of this study was to evaluate the clinical effectiveness of dental implants (Astra Tech Dental, Mölndal, Sweden) in the edentulous mandible immediately loaded with an electroeroded cast-titanium screw-retained fixed prosthesis. MATERIALS AND METHODS: Forty-five patients received five implants each in the interforaminal area. All the implants were inserted with torque up to 40 Ncm and the distal implants were distally tilted approximately 20 to 30 degrees to minimize the length of posterior cantilevers. Implants were loaded within 48 hours of placement with an acrylic resin-titanium screw-retained prosthesis fabricated by electroerosion. RESULTS: Two of the 225 inserted implants failed after 3 and 16 months of healing, respectively, with a cumulative survival rate of 99.1% and a prosthetic survival rate of 97.8%. CONCLUSION: Immediate loading of tilted dental implants inserted in the edentulous mandible with a screw-retained titanium definitive prosthesis fabricated with electrical discharge machining provide reliable and predictable results.

Temperature change during non-contact diode laser irradiation of implant surfaces.

A temperature increase of more than 10°C can compromise bone vitality. Laser radiation with different wavelengths has been used for the treatment of peri-implantitis, but little is known about the effect of laser irradiation on temperature rise on the implant surface. In this study, the temperature gradient (∆T) generated by laser irradiation of implant surface using two diode lasers (810 nm and a 980 nm) with 2 W of power has been recorded by two thermocouples (one in the cervical area and one in the apical area) and studied. The 810-nm diode laser showed the following results: after 60 s of irradiation with 2 W of continuous mode the temperature gradient in the cervical area of the implant (∆Tc) was 37.2°C, while in the apical area (∆Ta) was 27.2°C. The 980-nm diode laser showed the following results: after 60 s of irradiation with 2 W continuous mode ∆Tc was 41.1°C, and ∆Ta was 30.6°C. The 810-nm diode laser with 2 W continuous mode generated a temperature increase of 10°C after only 14 s. The 980-nm diode lasers groups produced a much more rapid temperature increase. In only 12 s, the continuous wave of 980 nm reached the 10°C temperature rise. From the present in vitro study it was concluded that the irradiation of implant surfaces with diode lasers may produce a temperature increase above the critical threshold (10°C ) after only 10 s.

The influence of verification jig on framework fit for nonsegmented fixed implant-supported complete denture.

PURPOSE: The purpose of this retrospective study was to assess if there was a difference in the likelihood of achieving passive fit when an implant-supported full-arch prosthesis framework is fabricated with or without the aid of a verification jig. MATERIALS AND METHODS: This investigation was approved by the University of Rochester Research Subject Review Board (protocol #RSRB00038482). Thirty edentulous patients, 49 to 73 years old (mean 61 years old), rehabilitated with a nonsegmented fixed implant-supported complete denture were included in the study. During the restorative process, final impressions were made using the pickup impression technique and elastomeric impression materials. For 16 patients, a verification jig was made (group J), while for the remaining 14 patients, a verification jig was not used (group NJ) and the framework was fabricated directly on the master cast. During the framework try-in appointment, the fit was assessed by clinical (Sheffield test) and radiographic inspection and recorded as passive or nonpassive. RESULTS: When a verification jig was used (group J, n = 16), all frameworks exhibited clinically passive fit, while when a verification jig was not used (group NJ, n = 14), only two frameworks fit. This difference was statistically significant (p < .001). CONCLUSIONS: Within the limitations of this retrospective study, the fabrication of a verification jig ensured clinically passive fit of metal frameworks in nonsegmented fixed implant-supported complete denture.