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PubMed2003

The effects of tubule orientation on fatigue crack growth in dentin.

The fracture of restored teeth is a significant obstacle to lifelong oral health. Recent studies suggest that fatigue cracks originate at flaws introduced during cavity preparation and that fatigue crack growth is a principle cause of restored tooth fractures. In this study, the rate of fatigue crack growth in bovine dentin was estimated under mode I cyclic loading. Double cantilever beam (DCB) specimens were obtained from bovine molars and subjected to high cycle fatigue loading (10(5) < N < 10(6)). The fatigue crack growth rates were measured and used to estimate the crack growth exponent and coefficient according to the Paris Law. The average fatigue crack growth exponent was 4.7 +/- 0.6 for crack growth parallel to the dentin tubules, which was significantly larger than 4.3 +/- 0.5 for crack growth perpendicular to the tubules (t-test, CI > 80%). Although the crack growth rates varied considerably, there was no significant dependence on tubule orientation or tubule density. However, specific features of the fracture surfaces and tendencies for crack curving away from the tubules suggested preferential fatigue crack growth perpendicular to the dentin tubules. Results from this study are being used to guide an experimental investigation of fatigue crack growth in human dentin.

Dentin↗
PubMed2003

Selecting treatment options and sequencing treatment in the replacement of 2 maxillary central incisors with implants: a case report.

This article describes treatment provided to replace 2 maxillary central incisors with implant-supported restorations. The site of a missing maxillary central incisor was treated utilizing a bone expansion technique to augment the labial hard and soft-tissue profiles at the time of implant placement. The adjacent central incisor tooth, although destined to be extracted, was retained to serve as an abutment for a fixed provisional restoration until the first implant was deemed to have successfully integrated. At the appointment to uncover this implant, the fractured tooth was extracted and an implant was immediately placed into the socket. The first implant was then used to support the provisional restoration during the healing phase of the second implant. The techniques utilized resulted in optimum soft-tissue contours, allowed the patient to have a comfortable and esthetic provisional restoration, and minimized the number of surgical procedures.

Adult↗
PubMed1993

The effects of enamel anisotropy on the distribution of stress in a tooth.

Enamel is thought to have highly anisotropic stiffness characteristics, because of its prismatic structure. It is probable that the enamel is stiffer in the prism direction compared with a direction perpendicular to it. The prisms are thought to run approximately perpendicular to the enamel-dentin junction. The curvilinear anisotropy that will result can readily be modeled by TOMECH, a finite element program developed at the University of Sheffield, since curvilinearity of mechanical properties is available as an automated feature of this program. The patterns of stress due to an external load were investigated in two-dimensional abstract models, and in a model of a mandibular second premolar, for both anisotropic and isotropic enamel. Results were compared with the commercial code ANSYS and good agreement obtained. Enamel with anisotropic properties was found to have a profoundly different stress distribution under load when compared with models with isotropic enamel. For isotropic enamel, the load path is directed through the stiff enamel shell, while for anisotropic enamel, the load path is directed into the dentin, as the load path follows the stiff direction of the enamel prisms. Thus, if enamel is indeed anisotropic, its function differs greatly from that suggested in previous hypotheses. Enamel with anisotropic material characteristics would provide a hard-wearing protective surface-coating while simultaneously diverting the load away from this brittle, low-tensile-strength phase, thus reducing the potential for tooth fracture.

Bite Force↗
PubMed2000

Efficacy of bonded and nonbonded amalgam in the treatment of teeth with incomplete fractures.

BACKGROUND: This clinical study compared the efficacy of adhesive-retained vs. pin-retained complex amalgam restorations in the treatment of molars with incomplete fractures. Both relief of chewing pain and cold sensitivity were evaluated at two weeks, three months and one year. METHODS: The authors treated 38 patients with a chief complaint of chewing sensitivity on vital molar teeth (40 teeth in the study). A random-number generator determined the treatment method for each tooth. Twenty teeth received bonded amalgam restorations. Twenty teeth received amalgapins or threaded pins to retain the amalgam. Teeth were evaluated for postoperative chewing sensitivity. A visual analog pain scale was used to evaluate cold response to a skin-refrigerant-soaked cotton pellet at each visit. After 12 months, all 40 teeth were available for evaluation. RESULTS: Chewing pain was completely eliminated in all but one tooth. A Student's t-test found no significant difference (P > .05) in preoperative cold sensitivity between the bonded and nonbonded groups. A paired t-test comparison indicated that the teeth in the bonded group were significantly less sensitive to cold after three months and 12 months than they were at the time of the baseline measurements (P < .0001). A paired t-test indicated no significant difference between preoperative and postoperative cold sensitivity scores for teeth in the nonbonded group (P > .05). CONCLUSIONS: Both adhesively bonded and mechanically retained complex amalgam restorations were successful in resolving chewing sensitivity in cracked molars. For 39 of 40 teeth, chewing sensitivity did not return during the one-year follow-up period. At three months and 12 months, cold sensitivity was reduced in the bonded restorations. At all three time periods, cold sensitivity remained similar to baseline levels for the mechanically retained restorations. CLINICAL IMPLICATIONS: Incomplete tooth fracture in molars can be successfully treated by covering fractured cusps with amalgam restorations. This study excluded teeth with prolonged sensitivity to a cold stimulus or those with periodontal evidence of root fracture. With these exclusions, elimination of chewing sensitivity was predictable. Teeth restored with bonded restorations experienced a decrease in sensitivity to a cold stimulus at three months and at 12 months, but not at two weeks. The cold sensitivity of teeth restored with nonbonded restorations was similar at baseline, two weeks, three months and one year.

Adult↗
PubMed2005

Apexification: a review.

This paper reviews the rationale and techniques for treatment of the non-vital immature tooth. The importance of careful case assessment and accurate pulpal diagnosis in the treatment of immature teeth with pulpal injury cannot be overemphasized. The treatment of choice for necrotic teeth is apexification, which is induction of apical closure to produce more favorable conditions for conventional root canal filling. The most commonly advocated medicament is calcium hydroxide, although recently considerable interest has been expressed in the use of mineral trioxide aggregate. Introduction of techniques for one-visit apexification provide an alternative treatment option in these cases. Success rates for calcium hydroxide apexification are high although risks such as reinfection and tooth fracture exist. Prospective clinical trials comparing this and one-visit apexification techniques are required.

Aluminum Compounds↗
PubMed1990

Three-year clinical performance of eight amalgam alloys.

Eight amalgam alloys were clinically assessed for fracture at the margins and tarnish after 3 years. The amalgams that exhibited the least fracture at the margins were Epoque. Dispersalloy and Amalcap. The alloys Permite, Lojic and Tytin followed closely behind and the materials Arjalloy and Futura showed the greatest amount of breakdown. Tytin had the highest luster with Lojic and Futura having a generally dark surface after 3 years clinical service. Of the 260 restorations, six had been lost due to (a) tooth fracture (three restorations), (b) bulk fracture of the amalgam (two restorations), and (c) endodontic treatment (one restoration).

Dental Amalgam↗
PubMed2002

The effect of two different root canal sealers and smear layer on resistance to root fracture.

The purpose of this in vitro study was to test the effect of Ketac-Endo (KE) and AH 26 on resistance to root fracture and also to evaluate the effect of smear layer. Seventy-two human maxillary canine teeth were randomly divided into six groups (n = 12) and were prepared using six different methods: group 1: KE, without smear layer (smear -); group 2: KE, with smear layer (smear +); group 3: AH 26, smear (-); group 4: AH 26, smear (+); group 5 (negative control): nonprepared; group 6 (positive control): prepared but unfilled. After storing 1 week in 100% humidity at 37 degrees C, the coronal lingual walls and root canal spaces were lowered 2 mm below the buccal walls of the roots. The samples were placed into acrylic resin blocks so that 10 mm of buccal roots were exposed and were placed in a specially designed steel pad at an angle of 15 degrees to the long axis of the root. A slowly increasing force was applied at the junction of the buccal wall and root canal space until fracture occurred. The force required to fracture each tooth was recorded as kg and statistically analyzed using one-way analysis of variance and Duncan tests. The results indicated that instrumentation of the root canals significantly weakened the tooth structure to fracture (p < 0.05). The canals obturated with either sealer were significantly stronger than roots whose canals were instrumented but not obturated (p < 0.05), and there was no difference between the sealers. The presence or absence of the smear layer did not cause any significant effect on the root fracture resistance of the teeth (p > 0.05).

Analysis of Variance↗
PubMedDate not supplied

Prosthodontic complications in a prospective clinical trial of single-stage implants at 36 months.

PURPOSE: The present material reports on prosthodontic complications in a trial of 51 patients with prostheses supported by single-stage implants over a period of 36 months. MATERIALS AND METHODS: One hundred eighty-six single-stage implants were placed in 51 patients over a 3-year period in 2 carefully controlled prospective clinical trials. Nineteen of the patients (103 implants) were completely edentulous and restored with a maxillary complete denture and a mandibular fixed-detachable complete prosthesis. Single metal-ceramic crowns or fixed partial dentures were fabricated for the remaining 32 patients (83 implants). The fixed restorations were either screw-retained or cemented. RESULTS: All patients/implants were followed for a minimum of 3 years. Complications in the edentulous patients included fracture of denture teeth, fracture of the maxillary denture, and occlusal screw loosening. Occlusal screw loosening and loss of the resin composite access plug were the only complications observed in the patients treated with screw-retained restorations. No complications were found in the patients restored with cemented restorations on solid abutments. DISCUSSION: Problems with prostheses were very common in the completely edentulous patients (13 of 19 patients encountered complications), possibly a result of increased bite force or inadequate laboratory technique. Tooth fractures were seen more frequently in men than in women. Complications occurred in only 5 of the 32 partially edentulous patients. CONCLUSION: Complications were associated with laboratory-related procedures rather than the implant system itself.

Adult↗
PubMed2006

Persistent orodental pain, atypical odontalgia, and phantom tooth pain: when are they neuropathic disorders?

Patients with unrelenting pain in the teeth, gingival, palatal or alveolar tissues often see multiple dentists and have multiple irreversible procedures performed and still have their pain. Up to one-third of patients attending a chronic facial pain clinic have undergone prior irreversible dental procedures for their pain without success. In these cases, if no local source of infectious, inflammatory, or other pathology can be found, then the differential diagnosis must include a focal neuropathic pain disorder. The common diagnoses given include the terms atypical odontalgia, persistent orodental pain, or if teeth have been extracted, phantom tooth pain. One possibility is that these pain complaints are due to a neuropathic alteration of the trigeminal nerve. There are several diagnostic procedures that need to be performed in any patient suspected of having a trigeminal neuropathic disorder including (1) cold testing of involved teeth for pulpal nonvitality; (2) a periapical radiograph examining the teeth for apical change; (3) a panoramic radiograph examining for other maxillofacial disease; (4) a thorough head and neck examination also looking for abnormality; (5) a cranial nerve examination including anesthetic testing which documents any increased or decreased nerve trigeminal nerve sensitivity and rules out other neurologic changes outside the trigeminal nerve; and (6) MRI imaging in some cases. Finally, when a nonobvious atypical toothache first presents, direct microscopic examination of the tooth for incomplete tooth fracture is also suggested. The majority of these patients are women over the age 30 with pain in the posterior teeth/alveolar arch. Multiple causes exist for sustained neuropathic pain including direct nerve injury (e.g., associated with fracture or surgical treatment), nerve injection injury, nerve compression injury (e.g., implant, osseous growth, neoplastic invasion) and infection-inflammation damage to the nerve itself. Sustained nerve pain is commonly seen in patients with psychiatric impairment. It may be that the unrelenting nature of the pain itself alters the patient's personality. Treatment includes pharmacologic medications which suppress nerve activity. The common medications used for atypical odontalgia and phantom tooth pain include gabapentin, tricyclics, topical anesthetics, and opioids. A list of these medications is provided in table form. Data suggest that once the patient has failed dental treatment and pain persists, the long-term outcome is less than 25 percent will have complete pain relief with treatment. With earlier treatment, better pain control, and improved nerve activity suppression medications, this should also prevent secondary psychiatric disease from developing and lower the number of inappropriate treatments.

Facial Pain↗
PubMedDate not supplied

Conditions to be considered in the differential diagnosis of child abuse and neglect.

Dentists and dental personnel have an obligation to report occurrences of child abuse and neglect (CAN). The general types of abuse and neglect are defined, as is dental neglect. Dental neglect is the "willful failure of parent or guardian to seek and follow through with treatment necessary to ensure a level of oral health essential for adequate function and freedom from pain and infection." Dentists and dental staff should be trained in recognizing and reporting abuse and neglect. In this training, consideration should be given to dental and medical conditions which mimic CAN. These include tooth fractures, nursing caries syndrome, rampant dental decay, skeletal injuries, dermatologic conditions, and genetic and certain congenital defects. The article reviews literature on the subject and includes photographs of conditions which could be mistaken for CAN.

Child↗
PubMed1987

Small animal dentistry: introduction to equipment, methodology and endodontic principles.

The anatomical structures of the teeth in dogs and cats, the occurrence and therapy of caries, tooth fractures and the different methods of endodontical therapy in fractured or inflamed teeth, like vital and mortal amputation (pulpotomy) and vital/mortal extirpation are shown. The principles of silver amalgam and "plastic" = composite resin material fillings are explained. Further informations on recommendable instruments, materials and equipment are added.

Animals↗
PubMed1977

[Indications and technic of transdental fixation].

Transdental fixation, as closed implant, offers the most favourable preconditions of all dental procedures of implantation. Teeth where the root-crown relation is altered to the detriment of root length, which is held firm in bone, can with its help be made functional. Loosening and premature loss of teeth can be prevented. Further discussed is the indication for this procedure, especially in tooth fractures and luxations as well as the operative steps. Up to now transdental fixation has proved itself although the number of cases and the follow-up time are insufficient to allow final judgment.

Dental Implantation, Endosseous, Endodontic↗
PubMedDate not supplied

The dental pathology of northern elephant seals (Mirounga angustirostris).

Skulls (n=104) of northern elephant seals from California were examined macroscopically. The animals varied in age but the numbers of each sex were roughly equal. The majority (86%) of teeth were available for examination. The mandibular first premolars were the most common teeth to be congenitally absent, with 2.3% missing. Supernumerary teeth (usually a supplemental mandibular molar) were associated with only 1.4% of normal teeth (or empty alveolar sockets). At least one persistent deciduous tooth was present in 38% of skulls, 70% of which were juvenile skulls. The majority (95.8%) of premolars had the type 2a tooth form, with only 3.8% and 0.5% of type 2b and 2c, respectively. Forty-six skulls, of which 43 were from adults, showed signs of attrition. Tooth fractures were uncommon, affecting only 33 teeth (1.2%). One skull showed an "incremental line" suggestive of enamel hypoplasia. Periodontal hard tissue lesions were seen in 44.3% of all teeth present (46.0% of skulls). Six cases of periapical disease with bone loss were observed.

Animal Diseases↗
PubMed1997

Towards the development of a standard test procedure for mouthguard assessment.

A simulated upper jaw, made from a rubber arch containing replaceable ceramic teeth and a renewable composite jawbone, offers promise in assessing the performance of custom made mouthguard designs. Impact tests, involving precise assessment of jaw and tooth fractures caused by projectiles of various energies and profiles, simulate conditions that approximate to common clinical observation. Such conditions offer the most sensitive indices for assessing both improved mouthguard designs and product quality and reliability. Damage caused by the dissipation of the impact energy may be transferred within this simulated oral cavity by minor changes to the impact conditions.

Equipment Design↗
PubMed2005

[Resistance to cyclic fatigue of pulpless teeth with flared root canals restored with different post-and-core materials].

OBJECTIVE: To investigate the resistance to cyclic fatigue of maxillary incisors with flared canals restored with different post-and-core materials. METHODS: Thirty human maxillary central incisors were assigned randomly to two main groups (non-ferrule and 1-mm ferrule) of 15. Each main group was then divided into 3 groups of 5 specimens and restored with custom cast post-and-core (MPC), resin composite post-and-core (RCP), and resin composite core combined with prefabricated carbon fiber post (FRC), respectively. Every group was subjected to a cyclic fatigue test, and recorded the numbers of load cycles that occurred tooth fracture. All data were analyzed with two-way ANOVA and the Tukey HSD test at alpha = 0.05. RESULTS: FRC revealed significantly higher fatigue strength than the other groups (P < 0.05). Preparing a dentin ferrule increased significantly fatigue resistance (P < 0.05). The favorable (retrieval) fracture pattern of the tested specimens was discovered only in RCP. CONCLUSIONS: Using FRC may get a long fatigue life in restoring pulpless teeth with flared canals. Dentin ferrule preparation is necessary to enhance resistance of the restorations to cyclic fatigue.

Carbon↗
PubMed1984

Oral findings in osteogenesis imperfecta.

The dentitions of twenty-eight patients, each of whom had either an autosomal dominant or a sporadic osteogenesis imperfecta (OI) syndrome, were evaluated. The diagnosis of dentinogenesis imperfecta (DI) could be established in all seven patients with dominantly inherited OI in three families, while all eight persons with dominant OI in three other families had normal teeth. Of the thirteen remaining patients with OI, twelve had no family history of the disorder; four had DI and eight had normal teeth. One person had a family history of OI and DI. All patients with abnormal tooth wear and spontaneous tooth fractures had DI. The DMF ratio increased with age in all patients with OI type I and was higher among the patients with OI type III and DI. Class III malocclusions were found in 66% of the patients. A statistically significant high incidence of impacted first and second molars was noted.

Adolescent↗
PubMed2001

Evaluation of the 1-year clinical performance of dentin-bonded ceramic crowns and four case reports.

OBJECTIVE: Dentin-bonded crowns are a comparatively recent addition to the dentist's armamentarium. Although 1-year data cannot predict the long-term performance of restorations, it may be useful for new treatment modalities, given that it will describe early, catastrophic failures. In this study, the 1-year performance of 109 dentin-bonded crowns was assessed. METHOD AND MATERIALS: The crowns were placed in two locations (Glasgow, Scotland, and Belfast, Northern Ireland) for 27 patients. The principal reasons for crown placement were tooth substance loss, esthetic reasons, and tooth fracture. Minimal preparations were used. Ninety-eight crowns were available for review at 1 year. RESULTS: Ninety crowns were found to be intact, six had a crack visible on transillumination and two had fractured. No crowns had debonded. No secondary caries was noted. No unsatisfactory scores were recorded for marginal adaptation, adjacent gingival health, or color match. CONCLUSION: The dentin-bonded crowns placed during this study provided good overall performance at 1 year.

Adolescent↗