What’s in a smile? Plenty, it turns out
Spontaneous smiles are more revealing than posed smiles, and women generally show more gingiva and teeth than men when they smile in either case. The findings are from a study published online August 2 in the Journal of Prosthetic Dentistry.
Authors designed the study to compare posed and spontaneous smiles in still and video images. They took 3 photos and 1 video clip from 380 participants (227 women, 153 men) aged 18-32. Authors used the camera from an 8-mexapixel iPhone 6 and artificial 5500 Kelvin light for all images. They positioned the camera 40 centimeters from the tip of the participant’s nose for still photos and 70 cm away for video clips. Lights were positioned at 45 degrees from the medial sagittal plane and 15 cm from the tip of the participant’s nose.
Authors classified smile lines on a 4-point scale: class 1, more than 2 mm of visible marginal gingiva or more than 2 mm visible apical to the cement-enamel junction (very high smile); class 2, 0-2 mm of visible marginal gingiva or 0-2 mm visible apical to the cement-enamel junction (high smile); class 3, only gingival embrasures visible (average smile); and class 4, gingival embrasures and cement-enamel junctions not visible (low smile).
Authors calculated the dental display at rest in photos from the incisal edge to the stomion of the upper lip. They calculated dentogingival display in posed and spontaneous smiles for men and women by measuring the distance from the incisal edge of the left maxillary central incisor to the lower edge of the upper lip following a vertical line. They calculated the difference in gingival display by subtracting the posed smile dentogingival display from the spontaneous smile dentogingival display. Authors calculated lip mobility by subtracting the dental display at rest from the dentogingival display distance in the spontaneous smile.
The authors found that women tended to show more dental display at rest, posed and spontaneous smiles, including lip mobility, than men. For posed smiles, authors observed class 3 smiles most often for women (54.5%) and men (52.9%), and noted class 1 smiles least often for women (7.9%) and men (0.6%). For spontaneous smiles, authors observed class 2 smiles most often for women (44.9%) and men (45.7%), and noted class 4 smiles least often for women (0%) and men (5.2%). Authors noted that 68.4% of the overall sample showed a change (p < .05) in smile type from posed to spontaneous, and that women presented a higher percentage of gingival display than men for posed and spontaneous smiles.
“The use of digital photographs alone for evaluation and treatment planning is incomplete because most of the participants showed a change in the type of smile from posed to spontaneous records,” the authors concluded. “Treatments should be planned individually because a wide range of maximum and minimum values for lip mobility, dental and dentogingival displays at rest, and posed and spontaneous smiles was observed.”
Read the original article here or contact the ADA Library & Archives for assistance.
Advertisement
Lithium disilicate, zirconia crowns, both reliable implant abutment options
Monolithic lithium disilicate and zirconia screw-retained crowns made using computer-aided design and computer-aided manufacturing (CAD-CAM) with a digital work flow are reliable options for restoring a missing tooth on implant abutments. The finding is from a study published online June 12 in The Journal of Prosthetic Dentistry.
Authors designed the cross-sectional retrospective clinical study to see how well lithium disilicate crowns compared with zirconia crowns to replace a single posterior tooth in a digital work flow. The study included 38 participants (21 women and 17 men, mean [standard deviation] age 65.6 [7.3] years) who received an implant-supported single crown restoration. One-half of participants received lithium disilicate crowns (LT group) and the other one-half received zirconia crowns (Z group). In the LT group, 10 crowns were in premolar sites and 9 were in molar sites. In the Z group, 8 crowns were in premolar sites and 11 crowns were in molar sites.
Authors considered the time of prosthesis delivery, interproximal contacts, and occlusion at baseline. Any adjustments to interproximal or occlusal surfaces were ranked on a 3-point scale: none, minimal or significant. Authors examined a total of 228 sites in 38 implants for probing depth and bleeding on probing at 1 week, and 1- and 3-year follow-up visits.
Authors obtained periapical radiographs using the long-cone parallel technique at baseline and the 3-year follow-up visit. They also recorded marginal bone loss and survival and success rates. Survival was defined as the crown being physically in the mouth. The success rate was based on the absence of any complications.
Authors inserted all fixtures according to manufacturer’s guidelines while the patient was under local anesthesia and then began prosthetic treatment after a 3-month healing period. Treatment included a digital scan of an implant-specific scan body to obtain a 3-dimensional rendering of the implant. Software was used to design and fabricate each crown. Interproximal and occlusal tightness was set at 25 Newton centimeters, and prefabricated abutments were used. All crowns were seated onto the implants using a manual torque control ratchet set at 35 Ncm. Authors calculated mean values, standard deviations, ranges, and frequency distributions.
Authors found comparable clinical outcomes for the LT and Z groups, each with a 100% survival rate. They also found no major technical complications in the LT and Z groups. Chipping of a functional cusp 23 months after prosthesis delivery was the only minor complication in the LT group. Screw loosening 29 months after prosthesis delivery was the only minor complication in the Z group. Authors considered both complications easily repaired and reported no soft-tissue inflammation in either group 1 week after prosthesis delivery. They noted no biological complications for either group but recorded a significant difference in white esthetic score (standard deviation) between the LT group (8.21 [1.65]) and the Z group (6.73 [0.73]).
Read the original article here or contact the ADA Library & Archives for assistance.
Advertisement
3D space requirements determine type of dental implant prosthesis
Restorative 3-dimensional space requirements should be the key factor in determining which type of dental implant prosthesis can be constructed, according to a study published in the August issue of The Journal of the American Dental Association. The authors based the recommendations on a combination of existing dental literature and their own clinical experience.
An important first step, the authors noted, is to establish the final position of prosthetic teeth and then work backward to determine needed restorative volume. The final prosthesis should be planned down from the occlusal plane, not up from the osseous crest. The distance from the implant platform to the height of the gingival margin is an important factor to measure available rehabilitative space for posterior teeth.
Authors noted that overbite should be considered for mandibular and maxillary anterior teeth. Potential restorative space for mandibular anterior teeth should be measured from the edentulous ridge to the cingulum area or lingual to the maxillary teeth. Potential restorative space for maxillary anterior teeth should be measured in the cingulum area of the proposed tooth either from the soft tissue or bone to the mandibular incisal edge position. Potential restorative space for a Class III jaw relationship or large maxillary overjet of the maxillary anterior dentition should be measured from the edentulous ridge where implant components will be located to the level of the opposing dentition. Potential restorative space for a Class III jaw relationship of the mandibular anterior dentition should be measured from the mandibular ridge to a height that corresponds to the incisal edge of maxillary teeth. Potential restorative space for a large maxillary overjet of the mandibular anterior dentition should be measured from the mandibular ridge that corresponds to the cingulum of the maxillary anterior teeth. Dentists also should record mesiodistal and buccolingual spaces that will be occupied by an implant restoration.
Authors recommended impressions and mounting working casts to determine ridge relationships, occlusal scheme, soft-tissue topography, and interarch space. They proposed a 3-tier system to measure restorative space with respect to horizontal ridge resorption: 0 through 4 millimeters (minimal); 5 through 10 mm (moderate); and more than 10 mm (advanced). For patients with minimal bone resorption, dentists should measure needed vertical space at the future location. For patients with moderate or advanced resorption, dentists should measure needed vertical space on the edentulous ridge, lingual or palatal to future tooth position.
Authors recommended fixed options in cases of minimal amounts of restorative space. Prosthesis design at the implant or abutment level and choice of esthetic materials are key factors to consider for screw-retained prostheses. The minimal vertical restorative space for a screw-retained, implant-level prosthesis is 4 to 5 mm measured from the implant platform to the opposing arch. A straight, low-profile, screw-retained transmucosal abutment-level restoration requires at least 7.5 mm of vertical space. A cement-retained implant restoration requires an interarch space of at least 7 through 8 mm, measured from the implant platform to the opposing dentition.
For unsplinted designs of removable implant prostheses, authors recommend a minimal vertical space of 7 mm for an unsplinted overdenture measured where prosthetic teeth are located and more palatally or lingually where implant components are positioned. The minimal vertical space needed for a bar overdenture is 11 mm. An abutment-level, screw-retained hybrid prosthesis needs at least 15 mm of vertical space, the most of any fixed option.
“Space requirements for each rehabilitation should be considered restoration specific,” the authors concluded. “… application of knowledge pertaining to restorative space considerations regarding various implant constructs should be considered a mandatory component of treatment planning.”
Read the original article here or contact the ADA Library & Archives for assistance.
Achievable root coverage: location, location, location
Tooth location is a key factor in determining how much root coverage is achievable, while maxillary multiple adjacent gingival recessions (MAGRs) showed greater mean root coverage (mRC) and complete root coverage (CRC) than mandibular MAGRs. Maxillary canines and incisors were associated with the highest outcomes compared with other sextants. The findings are from a study published online June 8 in Journal of Periodontology.
Authors designed the study to measure the impact of tooth location, flap design, and flap extension on the outcomes of MAGRs after a coronally advanced flap (CAF) with or without a connective tissue graft (CTG) was performed. They used mixed regression and logistics to measure the influence of factors on treatment outcomes by reanalyzing previously published clinical trials from 6 centers: 2 universities and 2 private practices in Italy, 1 university in Spain, and the University of Michigan in Ann Arbor.
The study’s primary outcome was the influence of tooth location on the mRC and CRC for 6 sextants: first (right maxilla), second (anterior maxilla), third (left maxilla), fourth (left mandible), fifth (anterior mandible), and sixth (right mandible). The study’s secondary outcome was the impact of flap design on outcomes, clinical attachment level gain, change in keratinized tissue width, and comparisons between CAF with or without CTG.
The study sample included 166 patients (102 women, 64 men, mean [standard deviation {SD}] age 35.8 [8.6] years) treated with 609 MAGRs. The CAF was used to treat 321 MAGRs, while a combined CAF and CTG was used to treat 288 MAGRs. The mean (SD) follow-up duration was 11 (2.2) months. Authors recorded data on patient age, sex, smoking habits, medical history, flap design, flap extension, and tooth location. They compiled measurements at baseline and follow-up on recession depth, probing depth, clinical attachment level, and keratinized tissue width.
Authors treated all MAGRs with an envelope or with 2 vertical releasing incisions. CTG was added in some cases over at least 1 root surface. The flap was then coronally advanced and sutured. Authors created mixed linear regression models for mRC, baseline recession depth, and keratinized mucosa and created mixed logistics models for CRC outcomes.
Authors found the overall mRC and CRC (SD) after CAF were 87.4% (18.7%) and 63.1%, respectively. They found the highest values (SD) for mRC and CRC (94.8% [10.6%] and 79.2%, respectively) for teeth treated in the second sextant, and noted significantly lower coverage for the fourth, fifth, and sixth sextants. They also found that maxillary MAGRs were associated with a significantly greater mRC and CRC than mandibular MAGRs.
When CAF was combined with CTG, the authors found the overall (SD) mRC and CRC was 94.13% (12.7%) and 78.9%, respectively. The highest mRC and CRC (SD) (97.4% [7.9%] and 89.7%, respectively) was found in the second sextant. Authors found the lowest values for mRC and CRC in the fifth and sixth sextants, respectively. They also found that maxillary MAGRs presented greater mRC and CRC values than mandibular MAGRs.
The mRC (SD) of sites treated with 2 vertical incisions (vCAF) and an envelope (eCAF) were 86.4% (20.5%) and 87.6% (18.4%), respectively. Authors found no differences for CRC outcomes (60% versus 63.6%, P >.05). When treatment with CAF alone was considered, authors observed that teeth in the center of the flap showed the most mRC and CRC compared with teeth in the mesial position of the flap and teeth in the distal position. When CAF was combined with CTG, teeth in the center of the flap showed the greatest mRC and CRC compared with teeth in the mesial and distal positions.
Read the original article here or contact the ADA Library & Archives for assistance.
How to choose the right cases for Icon treatment and tips for patient success
Two dentists describe their experiences with Icon resin infiltration therapy (DMG) for interproximal or white-spot lesions and useful tips for how they use both treatments in their practices. Get the free e-book, The Science and Benefits of Caries Infiltration, featuring tips on choosing cases for Icon treatment, tips for patient success, and more. Download Now >>
ADA CE Online courses
Need CE? ADA CE Online has hundreds of hours of CE that you can earn from the comfort of your own home. Too many to choose from? Take them all! Get unlimited access to the entire ADA CE online library, including JADA, for one year from purchase. Access anywhere, anytime. With new courses being added every month, you’ll never run out of education opportunities. Group subscriptions are also available, check it out now!
|
|
