Quintessence International, 01/2010

This article reports the 9-year clinical outcome of the two-stage surgical rehabilitation of a severely atrophic edentulous maxilla with a metal-resin fixed denture supported by implants anchored in the zygomatic bone and the maxilla. After clinical and radiographic examination, zygomatic implants were inserted bilaterally and four standard implants were placed in the anterior region of the maxilla. Six months later, the implants were loaded with a provisional acrylic resin denture, and the definitive implant-supported metal-resin fixed denture was provided 1 year after implant placement. After 9 years of follow-up, no painful symptoms, peri-implant inflammation or infection, implant instability, or bone resorption was observed. In the present case, the rehabilitation of severe maxillary atrophy using the zygomatic bone as a site for implant anchorage provided good long-term functional and esthetic results. Therefore, with proper case selection, correct indication, and knowledge of the surgical technique, the use of zygomatic implants associated with standard implants offers advantages in the rehabilitation of severely resorbed maxillae, especially in areas with inadequate bone quality and volume, without needing an additional bone grafting surgery, thereby shortening or avoiding hospital stay and reducing surgical morbidity. Keywords: atrophic maxilla, dental implants, zygomatic bone, zygomatic implants

Regional odontodysplasia is a rare developmental anomaly of the teeth that affects enamel and dentin. Its etiology is unknown, but the most accepted theory refers to circulatory disorders associated with vascular nevi. An uncommon case of regional odontodysplasia involving three quadrants of the jaws is reported. An 8-year-old boy was referred to the authors' institution with lack of teeth as a major symptom. There was no hereditary anomaly in the family. Extraoral examination revealed a brown discoloration on the skin on the right side of the face, neck, and chest. Detailed intraoral examination showed hypoplastic and carious teeth. Fistulae and gingival overgrowth were also observed. Radiographically, the affected teeth presented the pathognomonic image of "ghost teeth." Conservative treatment was instituted. Keywords: diagnosis

The finding of intraoral telangiectasias in two patients previously diagnosed with Raynaud disease is reported. Neither patient exhibited any other feature of CREST syndrome, namely, calcinosis cutis, esophageal dysfunction, or sclerodactyly. To the authors' knowledge, this is the first time intraoral telangiectasias has been reported in conjunction with Raynaud disease in the absence of any other features of CREST syndrome. Keywords: CREST syndrome, intraoral telangiectasias, Raynaud disease

Guided bone regeneration has proven effective for the reconstruction of localized bony defects around endosseous implants. Acellular dermal matrix has been used in a wide range of dental applications, including root coverage and keratinized tissue build-up. In this report, acellular dermal matrix was used as a membrane in implantation with simultaneous bone augmentation in resorbed mandible situations. The width of the ridge was well-preserved, and the buccal dehiscence defects were covered with regenerate bone. This surgical technique may provide the clinician with an option for implant therapy. Further randomized controlled studies over long periods of time are necessary to establish whether this procedure offers long-term benefits. Keywords: acellular dermal matrix, deproteinized bovine bone, implant, ridge augmentation

Objective: Maxillary incisors are the most prominent teeth, and their inclination plays an important role in esthetics. In orthodontics, the inclination of central incisors is usually determined by cephalometric analysis. This publication suggests an adjunctive clinical measure to determine this inclination. The objective of the study was to examine the correlation between the inclinations of maxillary incisors measured on a cephalometric lateral headfilm and the light reflection zone appearing on the buccal surface of the teeth on anterior intraoral photographs. Method and Materials: Maxillary incisor inclination, divided into three levels-proclination, normal inclination, and retroclination-of 65 patients was determined by means of cephalometric analysis, using three angular measurements (maxillary incisor to sella-nasion, maxillary incisor to Frankfort horizontal, and maxillary incisor to nasion-point A). The anterior intraoral photographs of the 65 patients were divided into 3 groups according to the reflection zone on the maxillary central incisors as determined from the photographs: incisal, middle, and gingival. The correlation and agreement between the two parameters were evaluated by chi-square and kappa statistics. Results: The light reflection zone on the tooth surface as it appears on intraoral photographs- incisal, middle, or gingival-correlated with statistical significance to the angular inclination of the teeth-proclination, normal inclination, and retroclination, respectively-as determined by means of cephalometric analysis (P .001). Conclusion: Incisor inclination can be determined by not only cephalometric analysis but also the light reflection zone viewed on the buccal surface of intraoral photographs. This method might be used as a new screening tool and further as an additional clinical tool for assessing treatment plans in orthodontics and other fields of dentistry. Keywords: cephalometric analysis, incisor inclination, light reflection zone, orthodontics

Objective: Bone platform switching results in an inward bone ring in the coronal part of an implant that is in continuity with the alveolar bone crest. Bone platform switching is achieved by using a dental implant with a reverse conical neck (RCN). A retrospective study was performed to determine the impact of RCN on crestal bone remodeling (CBR). Method and Materials: A series of 191 implants with the same morphology, but three slopes of RCN, were evaluated. Lost implants and CBR around implants still in place at the end of the follow-up were considered to investigate those variables potentially associated with the clinical outcome. Radiographic examinations were performed for each implant before surgery and at the end of the follow-up to detect the degree of CBR. Time-dependent cutoff values were used to select implants with higher CBR. These implants were considered unsuccessful. The Kaplan-Meier algorithm was applied to detect those variables potentially associated with the clinical outcome (ie, lost implants or implants with higher CBR). Results: Only 5 of 191 implants were lost (survival rate 97.4%). No statistical differences were detected among the studied variables by using lost implants. Conclusions: Although no statistical differences were detected among the three types of implants, the data seem to indicate a correlation between CBR and the slope of the RCN, with a better outcome for implants with a more angulated RCN. Keywords: alveolar crest, bone, implant, Kaplan-Meier algorithm, remodeling

Objective: Bond strength limitations of adhesive zirconia restorations have stood as a barrier against their widespread use. Selective infiltration etching is a new surface treatment that enhances bonding to zirconia-based materials. Beside bond strength, the performance of adhesive zirconia restorations could be affected by other variables. The aim of this study was to evaluate the influence of partial-retainer design on the failure load of selective infiltration-etched zirconia restorations. Method and Materials: Cantilever selective infiltration- etched zirconia restorations consisting of a pontic, a connector, and a single partial retainer were bonded to resin teeth (Filtek Z250, 3M ESPE). Four designs were tested: lingual, mesiolingual, buccal, and inlay retainers. A full-crown retainer was used as a control. The inner surface of each retainer received selective infiltration-etching surface treatment, and the specimens were bonded using a resin cement (Panavia F 2.0, Kuraray). Half of the cemented restorations were subjected to an artificial aging program (n = 10). The failure load and type of the bonded restorations were evaluated by applying axial load to the pontic. Two-way ANOVA and Tukey S post hoc tests were used to analyze the data (α = 0.05). Results: The partial-retainer design had a significant influence on the failure load of the tested restorations (F = 19.24, P .001), with the lingual design being the weakest. No significant difference was found between the full-crown, inlay, and buccal retainers. Artificial aging did not influence failure load of the tested restorations. SEM examination revealed that all specimens failed cohesively by fracture of the supporting tooth. The lingual design and the full-crown restorations were associated with complete coronal fracture of the supporting tooth, while minor coronal fractures were observed for the other three partial-retainer designs. Conclusions: The design of the partial retainer significantly influences the failure load and type of selective infiltration-etched zirconia restorations. The design of the partial retainer could affect the clinical performance of these restorations. Keywords: partial retainer, selective infiltration etching, zirconia restorations

Objective: To assess the influence of post-and-core systems on the resistance to fracture of mandibular premolars restored with metal crowns and a 2.0-mm cervical ferrule. Method and Materials: Forty extracted premolars were selected and divided into 4 groups of 10 teeth each. Samples were sectioned 2.0 mm coronal to the CEJ. Following canal preparation, four restorative treatments were performed: group 1, post and core cast in type IV gold alloy; group 2, prefabricated titanium post with composite resin core; group 3, prefabricated quartz-fiber post combined with composite resin core; and group 4, composite resin core without post. Posts (groups 1, 2, and 3) were cemented with resin cement. Metal crowns were fabricated using nickel-chromium alloy. Specimens were placed in acrylic resin blocks and filled up to 2.0 mm apical to the CEJ. Fracture resistance was assessed by applying a continuous compressive force on the buccal cusp of the crowns at a 45-degree angle until fracture. Results were analyzed using ANOVA and Tukey multiple comparison test at a significance level of 5%. Results: Mean loads at fracture were as follows: group 1 = 1,189.23 N, group 2 = 1,816.43 N, group 3 = 1,224.51 N, and group 4 = 2,010.63 N. Groups 2 and 4 presented statistically similar results; the same was observed in groups 1 and 3. However, groups 2 and 4 presented significantly better results than groups 1 and 3. Conclusion: Restoration of mandibular premolars with composite resin core (without post) showed an increased resistance to fracture when compared with other post-and-core systems whenever a minimum of 2.0 mm of remaining tooth structure was covered with a full metal crown (ferrule effect). Preservation of tooth structure was the most important factor in tooth resistance. Keywords: composite resin core, endodontically treated teeth, ferrule, post and core

Objective: Primary stability and micromovement of orthodontic mini-implants depends on a number of factors and influences clinical success or failure. The purpose of this study was to assess the behavior of orthodontic mini-implants upon initial load application. Method and Materials: Orthodontic mini-implants (n = 39) were inserted in the alveolar process of maxillary human cadaver specimens (n = 10). Increasing horizontal forces (up to 2.5 N) were applied, and triggered images were taken in 0.5-N load intervals. Additionally, peri-implant parameters based on micro-CT volume data were recorded. Data were subjected to a two-sided nonparametric Wilcoxon signed rank test, and betweengroup comparisons were assessed with a Mann-Whitney test (α = .05). Results: Initial load application led to displacement beyond elastic recovery of the surrounding bone after force release (P .001). Cortical thickness and insertion depth, despite numeric differences, did not reveal any statistical differences, while displacement of mini-implants was significantly affected by contact to neighboring teeth (P .001). Conclusions: Insertion technique and initial load application on orthodontic mini-implants may be regarded as two crucial factors for success, while repeated application of orthodontic force does not seem to increase screw mobility. Keywords: cortical bone thickness, human cadaver, maxillary bone, mini-implant, optical measurement, primary stability

Angiolymphoid hyperplasia with eosinophilia is a rare benign vascular lesion most commonly affecting the head and neck region. This article reports a case of a 26-year-old white woman with rapidly enlarging nodules of the upper lip and cheek treated successfully with oral corticosteroids and cetirizine. Morbidity and cosmetic deformity associated with radical surgery to the face and possible consequences of radiation treatment were avoided. There were no long-term complications. Keywords: angiolymphoid hyperplasia, eosinophilia, facial deformity, Kimura disease, oral corticosteroids

Objectives: To evaluate in vitro the effect of fluoride therapies on the surface roughness of human dental enamel exposed to bleaching agents. Method and Materials: Sixty-six specimens obtained from 33 third molars were centrally cut, mounted on acrylic resin supports, polished, and submitted to baseline surface roughness readings (RaB). Next, the specimens were distributed into 11 groups and exposed to one of the bleaching agents-16% carbamide peroxide (CP) or 35% hydrogen peroxide (HP)-and one of the fluoride therapies-0.05% NaF daily (DF); 0.2% NaF weekly (WF); 2% final topical fluoride (FTF); or 2% initial and final topical fluoride (IFTF). The positive control group specimens were exposed to neither bleaching agents nor fluoride therapies. The negative control group specimens were exposed to the bleaching agents but none of the fluoride therapies. After storage in artificial saliva for 7 days, final surface roughness readings (RaF) were taken. Percentage differences between RaB and RaF were analyzed by ANOVA and Tukey HSD tests at a P value of .05. Results: The bleaching agents CP and HP increased the surface roughness compared with the control group; FTF and IFTF reduced the surface roughness of enamel exposed to CP and HP; DF and WF did not reduce the surface roughness of enamel exposed to CP and HP. Conclusion: Both bleaching agents tested increased the surface roughness of dental enamel, and both topical fluoride therapies were effective at reducing the increase in enamel surface roughness after bleaching. Keywords: bleaching, carbamide peroxide, enamel, fluoride, hydrogen peroxide, roughness

Objective: To compare wear performance and resistance to crack propagation (K1C) of commercial restorative materials and their flowable variations. A potential correlation between three-body wear and fracture toughness, modulus of elasticity, fracture work, Vickers hardness, and filler content was investigated. Method and Materials: Seven restoratives (five composites, one ormocer, and one compomer) and their corresponding flowable materials were used to determine and compare the three-body wear with a bolus of millet-seed shells and rice food (Willytec). The wear characteristics were measured by profilometry after 50,000, 100,000, 150,000, and 200,000 loading cycles. The fracture toughness value, K1C (MPam1/2), for each single-edged notched specimen was measured in a three-point bending test (universal testing machine 1446, Zwick). Fracture work and modulus of elasticity were calculated from the load curves. Vickers hardness was measured (HV hardness tester, Zwick) according to DIN 50133. The veneering composite Sinfony (3M ESPE) was used as a reference material. Results: Heavily filled composites experienced less wear than their flowable variations. The nanofiller composites revealed better wear results than hybrid composites, compomers, and ormocers. After 200,000 load cycles, the lowest wear rates were detected for Grandio (14 µm; Voco), and the highest mean values were found for Dyract AP (104 µm; Dentsply DeTrey). The values for fracture toughness (K1C) ranged from 0.82 to 3.64 MPam1/2. Highest K1C data was exhibited by the nanocomposite Nanopaq (Schütz Dental). All tested restorative materials exhibited higher fracture toughness than their low-viscosity variations. Conclusions: The wear resistance of the newer generation composites with incorporated nanofiller or microfiller particles increased to a high extent. Flowables show less resistance against wear and crack propagation because of their lower filler content. The reduced mechanical properties limit their use as a restorative to small noncontact, low-stress clinical situations. Keywords: composite, flowables, fracture toughness, hardness, wear

Objective: Hydroxyapatite (HA) is used as a construction material for artificial supplementation of enamel tooth surfaces to improve oral hygiene. This study examined in vitro HA interactions with mutans streptococci (MS) and bacterial adherence to small (nanosize) crystal form of HA beads having a protean hexagonal structure. The adsorption and physical effects of HA employed in vivo is also described. Method and Materials: [3H-thymidine]-labeled streptococci were incubated with HA noncoated or coated with salivary components or salivary agglutinin peptide (SRCRP2), a receptor for streptococcal surface proteins. Bacterial adhesion activities on HA were measured by uptake of [3H-thymidine]. Application of HA paste in an individual tray was tried on the tooth surface, and its effects on the colony ratio of MS/total streptococci (TS) in saliva were analyzed by culture technique. Results: The adhesion assay showed that the binding of streptococci to HA was inhibited by coating with salivary components, whereas coating with SRCRP2 had nearly no influence on binding with or without Ca+. Further, treatment with HA decreased the adherence of Streptococci mutans to roughened enamel surfaces by one-third. In vivo application of a HA dentifrice to individual teeth demonstrated that the colony number ratio of MS/TS slowly decreased. Conclusion: MS adhesion to HA was restricted by both salivary components, except for SRCRP2, and the physical effects of HA; in addition, the material itself has a unique effect for removing MS from the oral cavity. Keywords: dental drug delivery system, hydroxyapatite, oral biofilm, oral hygiene, SRCRP2, Streptococcus mutans