looks good but what could be the stability of such a big repair of the broken incisor?

perhaps the patient may require RCT followed by a crown .

veerendra

Regards.

Regards.

case selection is very important for veneers. if there is less support for the veneers than they may come out very soon. From the images I feel that endo , followed by post and core ( at least for the patients left central) followed by a crown would be required.

regards,

veerendra

Starting color: We are all equipped with an inborn tooth color that ranges from yellow-brownish to greenish-grey, and intensifies over time. Yellow-brown is generally more responsive to bleaching than green-grey.

Translucency and thinness: These are also genetic traits that become more pronounced with age. While all teeth show some translucency, those that are opaque and thick have an advantage: they appear lighter in color, show more sparkle and are responsive to bleaching. Teeth that are thinner and more transparent – most notably the front teeth – have less of the pigment that is necessary for bleaching. According to cosmetic dentists, transparency is the only condition that cannot be corrected by any form of teeth whitening.

Eating habits: The habitual consumption of red wine, coffee, tea, cola, carrots, oranges and other deeply-colored beverages and foods causes considerable staining over the years. In addition, acidic foods such as citrus fruits and vinegar contribute to enamel erosion. As a result, the surface becomes more transparent and more of the yellow-colored dentin shows through.

Smoking habits: Nicotine leaves brownish deposits which slowly soak into the tooth structure and cause intrinsic discoloration.

Drugs / chemicals: Tetracycline usage during tooth formation produces dark grey or brown ribbon stains which are very difficult to remove. Excessive consumption of fluoride causes fluorosis and associated areas of white mottling.

Grinding: Most frequently caused by stress, teeth grinding (gnashing, bruxing, etc.) can add to micro-cracking in the teeth and can cause the biting edges to darken.

Trauma: Falls and other injuries can produce sizable cracks in the teeth, which collect large amounts of stains and debris.

CAUSES OF POST-RETAINED CROWN FAILURE
The failure of post-retained crowns has been documented in several clinical studies (Figure 1).3 Many of these studies indicate that the failure rate of restorations on pulpless teeth with post-and-cores is higher than that for restorations of vital teeth.3

 Restorative failure of an all-ceramic crown on the maxillary right central occurring after endodontic treatment. A minimum of a 1 mm collar on sound tooth structure is required for a ferrule design.

 After determining the desired post channel length (one half to two thirds length of canal), the gutta-percha was removed with a series of pre-shaping instruments (Gates Glidden [SybronEndo]) (Rebilda post reamer [VOCO]).
Several main causes of failure of post-retained restorations have been identified, including: recurrent caries, endodontic failure, periodontal disease, post dislodgement, cement failure, post-core separation, crown-core separation, loss of post retention, core fracture, loss of crown retention, post distortion, post fracture, tooth fracture, and root fracture.4-6 Also, corrosion of metallic posts has been proposed as a cause of root fracture.7

A COMPARISON OF CURRENT POST SYSTEMS

. The channel preparation for a prefabricated fiber-reinforced post was performed using a color-coded drill (Rebilda post drill [VOCO]), establishing the desired intraradicular length and size for the selected post.

The pre-selected fiber-reinforced composite post (Rebilda post [VOCO]) was placed into the channel space. The coronal height was measured and marked with a diamond disc to the desired length. The post is cleaned with alcohol, silanated (Ceramic Primer [VOCO]) for 60 seconds, and then air-dried.

Today, the clinician can choose from a variety of post-and-core systems for different endodontic and restorative requirements. These systems and methods are well-documented in the literature.8-10 However, no single system provides the perfect restorative solution for every clinical circumstance, and each situation requires an individual evaluation.

Custom Cast Posts
The traditional custom-cast dowel core provides a better geometric adaptation to excessively flared or elliptical canals, and almost always requires minimum tooth structure removal.1 Custom cast post-and-cores adapt well to canals with extremely tapered canals or those with a noncircular cross section and/or irregular shape, and roots with minimal remaining coronal tooth structure.9 Patterns for custom cast posts can be formed either directly in the mouth or indirectly in the laboratory. Regardless, this method requires 2 appointment visits and a laboratory fee.

 A dual-curing, self-etch adhesive (Futurabond DC [VOCO]) was applied with an applicator (Endo Tim [VOCO]) to the base of the post space and air-dried. Any excess adhesive was absorbed with an endodontic paper point using a rapid
intermittent movement. A dual-cure, resin cement (Bifix QM [VOCO]) was injected into the post channel using an angled tip (Intraoral Tip Type 1 [VOCO]). It is important to remove the tip slowly while injecting, to prevent incorporation of air bubbles.

 The fiber post was immediately inserted into the post hole to the base of the prepared channel and light-cured from different positions for 2 minutes (7a). After polymerization, the fiber post was cut with a diamond bur to the predetermined length. Never use a serrated instrument or shears because this can damage the integrity of the post (7b).
Also, because it is cast in an alloy with a modulus of elasticity that can be as high as 10 times greater than natural dentin,11 this possible incompatibility can create stress concentrations in the less rigid root, resulting in post separation and failure. Additionally, the transmission of occlusal forces through the metal core can focus stresses at specific regions of the root, causing root fracture.11 Furthermore, upon aesthetic consideration, the cast metallic post can result in discoloration and shadowing of the gingiva and the cervical aspect of the tooth.

PREFABRICATED POST-AND-CORE SYSTEMS
An alternative consideration is the prefabricated post-and-core system. Prefabricated post-and-core systems are classified according to their geometry (shape and configuration) and method of retention. The methods of retention are designated as active or passive. Active posts engage the dentinal walls of the preparation upon insertion, whereas passive posts do not engage the dentin, relying instead on cement for retention.1 The basic post shapes and surface configuration are tapered, serrated; tapered, smooth-sided; tapered, threaded; parallel, serrated; parallel, smooth-sided; and parallel, threaded. While active or threaded posts are more retentive than the passive posts, the active posts create high stress during placement and increase the susceptibility of root fracture when occlusal forces are applied. Parallel-sided serrated posts are the most retentive of the passive prefabricated posts, and the tapered smooth-sided posts are the least retentive of all designs.2

Prefabricated Metal Posts
Traditional prefabricated metal posts are made of platinum-gold-palladium, brass, nickel-chromium (stainless steel), pure titanium, titanium alloys, and chromium alloys.2,4 Although stainless steel is stronger, the potential for adverse tissue responses to the nickel has motivated the use of titanium alloy.12 Also, contributing factors to root fracture such as excessive stiffness (modulus of elasticity)13 and post corrosion2 from many of these metal posts have stimulated concerns about their use.

Prefabricated Nonmetallic Posts

The nonmetallic prefabricated posts have been developed as alternatives, including ceramic (white zirconium oxide) and fiber-reinforced resin posts. Zirconium oxide posts have a high flexural strength, are biocompatible, and are corrosion resistant. However, this material is difficult to cut intraorally with a diamond, and to remove from the canal for retreatment.4 The fiber-reinforced composite resin post-and-core system offers several advantages: a one appointment technique, no laboratory fees, no corrosion, negligible root fracture, no designated orifice size, increased retention resulting from surface irregularities, conserved tooth structure, and no negative effect on aesthetics.

THE FERRULE EFFECT

The successful rehabilitation of any endodontically treated tooth using the post-retained system requires the consideration of one specific structural design characteristic: the ferrule effect. The stability of the crown is influenced by the preparation design for endodontically treated teeth. Preserving tooth structure during preparation is paramount in preventing stress concentrations at the cementoenamel junction of the endodontically restored tooth and provides resistance to tooth fracture. The completed crown preparation should have a ferrule design that encapsulates the endodontically re-stored tooth complex. This collar effect provides an antirotational feature for the stability of the crown. Clinical studies have demonstrated and confirmed the importance of this coronal tooth “collar” on the mechanical resistance and retention form of the endodontically restored tooth complex.14 The general guideline is a 1.0 to 2.0 mm preparation on sound tooth structure. Procedures that provide a shoulder on tooth structure, and an axial preparation on the core buildup, will have an insufficient ferrule design. In cases where there is insufficient sound tooth structure for a ferrule design, it is necessary to obtain this dimension through periodontal crown lengthening and/or forced-tooth-eruption procedures.

"It’ll solve a couple of different problems," Duff told DrBicuspid.com. "The first and foremost is the issue of shrinkage, one of the biggest issues in restoratives. I think these materials will help out in the industry by having the low volumetric shrinkage and the high conversion. Additionally, they will help toughen up the composite so that they tend to flex rather than break or crack."

Leakage of uncured or residual monomer, a potential outcome of low conversion, can be associated with allergic reactions and sensitization, he and his colleagues noted.

“It’ll solve a couple of different problems.”
— Jim Duff, Esstech
Their research found that Exothanes could enhance the strength and limit shrinkage in traditional dental restoratives utilizing methacrylate chemistry, which the industry is already familiar with. The material outperformed the controls displaying higher conversion, lower volumetric shrinkage, and 80% lower shrinkage stress in addition to "superior results in toughness and percent elongation," they reported.

Duff and his team suggest two means of harnessing the potential of the resins: They could be used neat, as a liner material, where their high elongation and toughness will help prevent cracking and caries formation; and they could be used as functional additives to improve the physical properties of existing formulations.

‘Interesting molecules’

The company’s foray into this aspect of restoratives was a result of Duff’s enthusiasm for chemistry.

"The project came out of an unrelated side project I was working on with some interesting molecules that I thought I could make," Duff explained. "So I made them and did some testing on their mechanical properties. At that point, I got my boss’ attention, and we sent them out for shrinkage and conversion testing — and that’s when everybody got really interested in them because they came back with such good numbers."

Esstech combined Duff’s efforts with previous work done on Exothane 10, the company’s first attempt at making a low-shrinkage, high-conversion material.

"We had that one on the shelf in research and development for four years, but we didn’t really know what to do with it, to be honest" Duff said. "The low-refractive index was a challenge for us, because dental materials companies want something that has a higher refractive index for the surface layer of the composite."

The results from testing efforts changed their minds, and the company created other Exothanes, numbered 8, 9, 26, and 32. One other material, Exothane 24, performs differently due to its "higher functionality," according to Duff.

For the AADR study, researchers compared the six Exothane elastomers to a BisGMA:TEGDMA blend (70:30) resin and a urethane dimethacrylate (UDMA) resin. Conversion and reaction kinetics were monitored with the near-infrared reflectance spectrum using Fourier transform infrared spectroscopy. They found that, overall, the Exothanes displayed considerably higher final conversion levels ranging from 94% to 98%.

The researchers also used a linometer to test volumetric shrinkage and found that the BisGMA:TEGDMA blend, UDMA, and Exothane 24 resulted in the greatest volumetric shrinkage and the lowest conversion values. The Exothane 24 possesses higher volumetric shrinkage and lower conversion due to its increased methacrylate functionality, they noted. In addition, "the low conversion does not necessarily indicate poor reactivity," they wrote.

Finally, the researchers used a tensometer to determine polymerization shrinkage stress, noting that "the highly functional Exothane 24 had the highest shrinkage stress" followed by the two control materials. During tensile testing, in which data were obtained by curing the Exothanes and the traditional polymeric matrix resins under a 600-W UVA light, all Exothanes proved to be significantly tougher than the controls, they noted.

"All of these attributes suggest that Exothanes would increase the durability of dental composites," the researchers concluded.

Researchers from the Ruprecht Karls University School of Dental Medicine searched the Cochrane Library and Medline from January 1, 1975, to December 31, 2010, and selected 35 studies that focused on assessment strategies for dental professionals.

They were interested in doing this research because they were performing a number of aesthetic corrections on sound anterior teeth in the upper and lower jaw with direct resin composite buildups and wanted to measure the treatment outcome before and after the aesthetic correction, lead study author Cornelia Frese, DMD, told DrBicuspid.com.

"But we could not find a suitable tool for it," she said. "This is why I started to look over the literature, to find some quantifiable parameters."

A more systematic approach

The primary inclusion criteria for the studies in the review were intraoral and extraoral aesthetic assessment methods and indexes or rating scales evaluating aesthetics in restorative dentistry.

The researchers’ goal was to classify the different methods and extract quantifiable clinical parameters that might help in developing an index to be used for diagnosis, treatment planning, and outcome assessment.

“It is no surprise that not all the studies are in agreement.”
— Ronald Goldstein DDS
After reading the qualifying articles, the study authors sorted and grouped the studies into six categories according to their aesthetic assessment topic: golden proportion, soft-tissue measurement, smile and smile line assessment, orofacial indexes and scales, incisor proportion and angulation, and facial aesthetics. These categories included various aesthetic parameters.

Through their review, the authors identified seven parameters that are sufficiently and reasonably quantifiable: the smile line, lip line, incisal offset, location of dental and facial midline, incisor angulations and width-to-height ratios of the maxillary anterior teeth, gingival contour, and root coverage and papilla height.

"These parameters should be considered when providing dental treatment in the anterior area, as they allow for quantification and objective judgment," the study authors noted.

They hope that these findings might increase interest in a comprehensive dental aesthetic index.

"Although aesthetic feelings and sensations are influenced by sex, race, regionalism, and people’s self-perceptions, the seven specified parameters we identified are accepted widely in the West," the authors noted. "If these guidelines are used in careful agreement with the patient’s needs and expectations, both the dentist and the patient may achieve a satisfying aesthetical rehabilitation."

Computer-aided diagnostics

This is an important study because it attempts to summarize the 35 studies dealing with assessment of dentofacial aesthetics, according to Ronald Goldstein, DDS, one of the founders and past president of the American Academy of Esthetic Dentistry and author of Change Your Smile.

"It is no surprise that not all the studies are in agreement," he said. "Nor will they ever be."

However, studies like the ones described in the JADA article can be helpful, along with various tools and techniques employed by the dental profession, in working to achieve an aesthetic result pleasing to the patient, he added.

"One missing ingredient from the studies is the psychological interaction between dentist and patient, especially the demanding and picky patient and the patient who cannot even make a positive final decision about what he or she really wants," he said. "What I see in the future and one of the most certain predictions I make is that computer-aided diagnosis and treatment planning especially for aesthetics will be the norm within a decade."

At least one of the parameters identified by the JADA review has previously been recognized as a valid parameter for aesthetic evaluation.

A systematic literature review conducted by a German team reviewed the evidence on the validity and universal applicability of the smile line (European Journal of Esthetic Dentistry, Autumn 2011, No. 3, pp. 314-327).

"The smile line is a valid tool to assess the aesthetic appearance of a smile," concluded the authors of that study. "It can be applied universally as clinicians and laypersons perceive and judge it similarly."

Other studies also have identified aesthetic guidelines and standards that can be useful to clinicians during cosmetic restorative procedures (JADA, January 2001, Vol. 132:1, pp. 39-45). The authors of that study noted that the overall aesthetic impact of a smile can be divided into four specific areas: gingival aesthetics, facial aesthetics, microaesthetics, and macroaesthetics.

Further research is needed to establish and validate a common dental aesthetic index, according to the authors of this latest JADA review.

"At the moment, we are conducting a pilot study in our department to see if the identified parameters of this review are able to measure changes and differences in facial aesthetics, and if the measurements of aesthetics are objective, reproducible, and consistent," Dr. Frese said. "If we should succeed in our pilot study, these results might be beneficial for dentists in the future."